ALBERT

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): X.Y. Wang, S.L. Zhang, S.D. Feng, L. Qi, R.P. Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The structures of the Ti〈sub〉75〈/sub〉Al〈sub〉25〈/sub〉 alloy during rapid-quenching with and without external pressure are investigated by using molecular dynamic techniques. The amorphous phase can be obtained at the cooling rate 10.0 K/ps without pressure. The alloy is composed of crystal and amorphous phase at the cooling rate 0.1 and 1.0 K/ps without pressure, but the pure amorphous phase can be formed when the pressure exceeds the critical value. The critical pressure is about 20 and 30 GPa when the cooling rate is 0.1 and 1.0 K/ps, respectively. H-A indices analysis indicates that high pressure favors the formation of the ideal icosahedral structures in the amorphous Ti〈sub〉75〈/sub〉Al〈sub〉25〈/sub〉 alloy, and the content of 1551 bond-type can reach near to 50% when the pressure is 30 GPa. The amorphous state can be maintained if the external pressure is removed from the alloy step-by-step. The content of 1551 bond-type decreases with the deceasing of the pressure, but the 1541 and 1431 bond-types increase in this process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Anne-Isabelle Bidegaray, Andrea Ceglia, Maria Rita Cicconi, Van-Thai Pham, Amandine Crabbé, El Amine Mernissi Cherigui, Karin Nys, Herman Terryn, Daniel R. Neuville, Stéphane Godet〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The analysis of iron, manganese and antimony in silicate glass is of great interest in chemistry, materials science, earth sciences and archaeological sciences. Yet, conclusions from different fields appear to be contradictory and many questions about redox reactions in glass remain. The purpose of this study is thus to discuss whether and how these multivalent elements interact in glass. Soda-lime silicate melts containing iron along with manganese and/or antimony have been analysed at different high temperatures under argon atmosphere. Using 〈em〉in-situ〈/em〉 XANES at the Fe K-edge, redox thermodynamics, kinetics and diffusivities have been assessed for the different compositions. The data obtained show that antimony is more efficient at oxidising iron compared to manganese at all temperatures. The oxidising power trend would thus be Sb 〉 Sb + Mn 〉 Mn. Furthermore, hypotheses on the formation of Fe-Mn complexes are also reported in glasses with stoichiometric proportions of iron and manganese. Based on the determination of redox diffusivities, it appears that presence of other multivalent elements does not significantly affect the iron redox mechanisms and that diffusivity is essentially controlled by the mobility of calcium.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Wentao Zhang, Feng He, Junlin Xie, Xiaoqing Liu, De Fang, Hu Yang, Zhihong Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Glass ceramics from modified molten blast furnace (BF) slag were prepared. The crystallization behavior of the modified BF slag was characterized using differential thermal analysis (DTA), X-ray diffraction (XRD), and field emission scanning electron microscope (FESEM). The crystallization kinetics results indicated that the crystallization activation energy initially decreased and subsequently increased with increasing CaO/SiO〈sub〉2〈/sub〉. The crystallization temperature and the crystallization index (n) decreased from 916 to 867 °C, and 5.66–1.13, respectively. The crystallization mechanism transformed from bulk crystallization to surface crystallization. By XRD analyzing, Melilite was developed as the main crystal phase, and the transformation of crystal from akermanite to gehlenite was observed. The rapid surface crystallization was beneficial for maintaining the shape of glass ceramics. The complex replacement in melilite crystals resulted in the micro cracks in glass ceramics, therefore led to the decrease of flexural strength of glass ceramics〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): B.C. Jamalaiah〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different amounts of GeO〈sub〉2〈/sub〉 activated tellurite tungstate glasses were prepared by melt quenching technique. Thermal stability and glass forming ability were studied using differential scanning calorimetry. The chemical composition, homogeneity and amorphous nature of studied glasses were investigated. The phonon energy was estimated to be 721.34 cm〈sup〉−1〈/sup〉. Experimentally determined refractive indices were compared with those determined from optical band gap (E〈sub〉g〈/sub〉) and optical electronegativity (Δ〈em〉χ〈/em〉〈sup〉∗〈/sup〉). The dielectric constant (K) and electronic polarizability (α) were determined using refractive index value. The presence of disorder was estimated in terms of Urbach energy (E〈sub〉U〈/sub〉). The average electronegativity (〈em〉χ〈/em〉〈sub〉〈em〉ave〈/em〉〈/sub〉), oxide ion polarizability (〈em〉α〈/em〉〈sub〉〈em〉O〈/em〉〈/sub〉〈sup〉2−〈/sup〉) and covalent character (C〈sub〉cov〈/sub〉) were determined. The content of GeO〈sub〉2〈/sub〉 was optimized to be 10.0 mol% to design a novel host material for solid state lasers and fiber devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Chunhe Jiang, Kejiang Li, Jianliang Zhang, Qinghua Qin, Zhengjian Liu, Minmin Sun, Ziming Wang, Wang Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉SiO〈sub〉2〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-CaO-MgO is the most significant slag system in the blast furnace ironmaking process and it is very important to investigate the microstructure and viscosity of the system. In this paper, molecular dynamics simulations were carried out to explore the effects of MgO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ratio on structure and properties of the system. Based on the self-diffusion coefficients, the viscosities were calculated by Einstein-Stokes equation and compared with the experimental value and the Factsage value. The results showed that with the increase of MgO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ratio, the stability of [SiO〈sub〉4〈/sub〉]〈sup〉4−〈/sup〉 and [AlO〈sub〉4〈/sub〉]〈sup〉5−〈/sup〉 tetrahedron became weaken and the relative proportions of bridge and non-bridge oxygen showed a decrease. And due to the increase of MgO, more Mg〈sup〉2+〈/sup〉 ions are used as network modifiers to reduce the degree of polymerization of the system, resulting in a decrease in the viscosity, which is consistent with experimental results. Finally, based on the present study, in the case of increasing Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content of blast furnace slag, the fluidity of slag could be adjusted by controlling MgO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ratio, thereby providing a basis for stable operation of blast furnace ironmaking.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): A.I. Popov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The definition of glassy state presented by the authors of the article “The glassy state of matter: Its definition and ultimate fate” E. Zanotto and J. Mauro is considered. The importance of the contribution to the glassy state problem made in the article is emphasized. At the same time consideration of the glassy state as unstable state of matter causes definite objections. It is more correctly to consider the glassy state as metastable state of matter.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): M.G. Syamala Rao, M.A. Pacheco-Zuñiga, L.A. Garcia-Cerda, G. Gutiérrez-Heredia, J.A. Torres Ochoa, M.A. Quevedo López, R. Ramírez-Bon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we developed a novel inorganic-organic hybrid gate dielectric by combining zirconium and hafnium components to form zirconium hafnium oxide strongly linked with polymethyl methacrylate (ZrHfO〈sub〉2〈/sub〉-PMMA) and deposited at low temperature (200 °C) by sol-gel method. The obtained 108 nm thick, high-quality hybrid gate dielectric showed an exceptionally low surface roughness (0.9-nm), a low leakage current density (7.7 × 10〈sup〉−6〈/sup〉 A/cm〈sup〉2〈/sup〉) and reasonable dielectric properties such as gate capacitance along with dielectric constant (77 nF/cm〈sup〉2〈/sup〉 & 9.4 @1 kHz) respectively. To examine the ZrHfO〈sub〉2〈/sub〉-PMMA hybrid dielectric electrical properties we constructed thin-film transistors (TFTs) with room temperature r.f sputtered n-type metal oxide semiconductors, a-IGZO and ZnO, as active channels. The bottom gate fabricated a-IGZO TFTs driving at as low as below 6 V, with extracted field effect mobility of 2.45 cm〈sup〉2〈/sup〉/V. s, a low threshold voltage of 1.2 V with large ON/OFF current ratio 10〈sup〉7〈/sup〉 respectively. On the other hand, for comparison we employed ZnO TFTs by applying same hybrid dielectric system, the obtained parameters of bottom gate ZnO TFTs were good field effect saturation mobility of 12.8 cm〈sup〉2〈/sup〉/V. s, threshold voltage of 1.8 V and ON/OFF current ratio of 10〈sup〉3〈/sup〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Weidi Zhu, Mark Lockhart, Bruce Aitken, Sabyasachi Sen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The viscoelastic properties of supercooled As〈sub〉x〈/sub〉Se〈sub〉100-x〈/sub〉 (0 ≤ x ≤ 30) and As〈sub〉x〈/sub〉Se〈sub〉100-x-y〈/sub〉I〈sub〉y〈/sub〉 (x = 20, 30 and y = 10, 20) liquids are studied using oscillatory parallel plate rheometry. In addition to the α-relaxation process, the shear relaxation of liquids with selenium chains longer than ~ 3 atoms is also characterized by a low-frequency polymeric mode. The temporal decoupling of this low-frequency soft/floppy relaxation mode from that of the α-relaxation mode is a unique function of the average selenium chain length. The floppy mode abruptly vanishes for liquids with average chain lengths shorter than ~ 3 Se atoms, thus implying a dynamical rigidity transition. When taken together, these results indicate that, contrary to the conventional wisdom, the pertinent structural variable associated with such transition in the viscoelastic behavior is not the average coordination number but instead the intermediate-range structural elements such as the average selenium chain length.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): M.S.A. Mohd Saidi, S.K. Ghoshal, K. Hamzah, R. Arifin, M.F. Omar, M.K. Roslan, E.S. Sazali〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the influence of silver (Ag) and titania (TiO〈sub〉2〈/sub〉) nanoparticles (ATNPs) co-embedment on the photoluminescence (PL) properties of dysprosium ions (Dy〈sup〉3+〈/sup〉) doped zinc-magnesium tellurite glass system prepared using conventional melt quenching method. Both up- and down- converted PL spectra of glasses revealed three emission bands located at 482 (blue: 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉15/2〈/sub〉), 574 (yellow: 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉13/2〈/sub〉) and 664 nm (weak red: 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉11/2〈/sub〉), where the band intensities were enhanced with the inclusion of ATNPs. Glasses with 0.2 mol% of ANPs and up to 0.3 mol% of TNPs disclosed highest PL intensity enhancement, which was majorly attributed to the ATNPs mediated localized surface plasmon resonance (LSPR) and large field enhancement (called hot spot) effects in the proximity of Dy〈sup〉3+〈/sup〉 ions. Absorption spectra of glasses displayed two plasmon bands characteristics of each type of nanoparticle. It was inferred that the superposition of localized SP modes from ATNPs could generate new hybridized modes (strong local field in the vicinity of Dy〈sup〉3+〈/sup〉 ions) shifted with respect to the single type of NPs resonance. HRTEM images showed the existence of both Ag and titania NPs inside the glass matrix. Glasses containing ATNPs exhibited anatase phase with (103) and (112) nanocrystalline lattice plane orientation. Proposed glass system may be useful for the development of solid state laser and photonic devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): G. Gorni, M.J. Pascual, A. Caballero, J.J. Velázquez, J. Mosa, Y. Castro, A. Durán〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The crystallization mechanism of LaF〈sub〉3〈/sub〉 in sol-gel oxyfluoride glass-ceramics in the system SiO〈sub〉2〈/sub〉-LaF〈sub〉3〈/sub〉 has been studied using DTA, XRD, FTIR, HRTEM and NMR. Based on classical calculations of non-isothermal DTA curves involving Ozawas's plots, a diffusion-controlled process should be responsible for the fluorides crystallization similarly to that obtained for melt-quenching oxyfluoride glass-ceramics. Therefore, an increase of the crystal size and fraction is expected when increasing the time and/or temperature of the treatment. Nevertheless, XRD, FIR, HRTEM and NMR demonstrated that neither bigger crystals nor higher crystal fraction are obtained for treatment times longer than 1 min at 550 °C. However, further heat treatment causes that the structural order of the crystals is lost. On the other hand, typical fluorides crystallization temperatures (~300 °C) in sol-gel materials are much lower than T〈sub〉g〈/sub〉 of the matrix (~1130 °C) thus being very different to what observed for oxyfluoride glasses prepared by melt-quenching. The proposed crystallization mechanism is a fast process that occurs when crystallization temperature is reached. This behavior is explained as a chemical reaction from the xerogels, followed by the fast precipitation of the nanocrystals without energy barrier. The nanocrystals are unstable in the surrounding SiO〈sub〉2〈/sub〉 matrix for aging at crystallization or higher temperatures. These treatments lead to a dissolution process, favored by the compositional gradient between matrix and crystals, which drive the material to reach the equilibrium.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Jürn W.P. Schmelzer, Alexander S. Abyzov, Vladimir M. Fokin, Christoph Schick〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉General relations for the dependence of the thermodynamic driving force of crystallization and the specific interfacial energy melt-crystal of critical crystal clusters on temperature and pressure are derived. Its application to the analysis of experimental data on crystal nucleation seems to support at a first glance a proposal by Kauzmann on the existence of a pseudo-spinodal curve in melt-crystallization. Provided this assumption is true, Kauzmann temperature (and for pressure-induced nucleation, the Kauzmann pressure) cannot be reached by a metastable liquid due to intensive crystallization processes occurring in its vicinity. However, such suggestion cannot be retained taking into account the kinetic terms (diffusion coefficients, viscosity) in the expression for the nucleation rate. The absence of a pseudo-spinodal in melt-crystallization can be verified also in an alternative way by considering the characteristic time scales of crystallization and relaxation. Finally, it is shown that the phenomenon denoted commonly as Kauzmann paradox is merely an untypical as compared to normal conditions type of behavior. Neither in its original formulation nor in its consequences it results in any contradictions with basic laws of nature. They are prevented either by normal (not associated with a pseudo-spinodal) crystallization or a conventional glass transition.〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): J. Gilabert, M.P. Gómez-Tena, V. Sanz, S. Mestre〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The effect of a post-synthesis thermal treatment on CoCr〈sub〉2−2Ψ〈/sub〉Al〈sub〉2Ψ〈/sub〉O〈sub〉4〈/sub〉 (0.0 ≤ Ψ ≤ 1.0) ceramic pigments synthesized by Solution Combustion Synthesis (SCS) has been studied. As-synthesized SCS pigments were treated at two different calcination temperatures (800 °C and 1000 °C) to study changes in mineralogy, microstructure and thermal behaviour, as well as their effect over the colouring power.〈/p〉 〈p〉Spinel-type 〈em〉Fd〈/em〉-3〈em〉m〈/em〉 crystalline structure was developed in all cases. Nevertheless, crystallinity parameters were highly affected by both analysed processing parameters: composition (Ψ) and post-synthesis calcination temperature (T〈sub〉c〈/sub〉). A Cr(III) enrichment along with T〈sub〉c〈/sub〉 increase favoured ion rearrangement to promote sample crystallization and crystallite growth. Fast kinetics of SCS makes Al-rich spinels with transition metals difficult to be synthesized. The application of a secondary thermal treatment resulted in a favourable evolution towards a well-crystallized structure. Lattice parameter did not seem to be affected by T〈sub〉c〈/sub〉, although it evolved indeed with composition. From a microstructural point of view, as-synthesized pigments were foamy, with a very low bulk density and nanometric grain size. After the thermal treatment, larger grain sizes were obtained, especially for the samples richer in Al and treated at higher T〈sub〉c〈/sub〉.〈/p〉 〈p〉All pigments developed intense colours in a transparent glaze without showing heterogeneities, indicating a stable behaviour against glazing process. Glaze colour evolved from green to perfectly blue shades, indicating an important dependence on composition. Nevertheless, colouring power seemed to be rather affected by calcination process.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Joanna Pisarska, Marta Sołtys, Joanna Janek, Agata Górny, Ewa Pietrasik, Tomasz Goryczka, Wojciech A. Pisarski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxyfluoride lead-based and lead-free germanate glasses were heat-treated in order to fabricate transparent glass-ceramics. Cubic β-PbF〈sub〉2〈/sub〉 nanocrystals are well formed during crystallization of lead germanate glass. The up-conversion luminescence spectra of Er〈sup〉3+〈/sup〉 ions in lead germanate glass-ceramic system are enhanced significantly due to partial incorporation of the optically active ions into fluoride crystalline phase. These effects are not significant in oxyfluoride lead-free germanate glass after heat treatment process. The crystallization of barium gallo-germanate glass with BaF〈sub〉2〈/sub〉 is more complex and the presence of four crystalline phases BaF〈sub〉2〈/sub〉, BaO, Ba〈sub〉3〈/sub〉Ga〈sub〉2〈/sub〉Ge〈sub〉4〈/sub〉O〈sub〉14〈/sub〉 and GeO〈sub〉2〈/sub〉 was verified by X-ray diffraction measurements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Edgar D. Zanotto, John C. Mauro〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The comment by Popov raises two questions related to (a) whether the glassy state can more appropriately be described as 〈em〉metastable〈/em〉 or 〈em〉unstable〈/em〉 and (b) whether the supercooled liquid state exists below the glass transition temperature, 〈em〉T〈/em〉〈sub〉g〈/sub〉. We argue that the glassy state is thermodynamically unstable, as it continuously and spontaneously relaxes toward the metastable supercooled liquid state at any nonzero temperature. Moreover, the supercooled liquid state—the target for the glass relaxation process—exists at any temperature below the liquidus temperature of a system. There is no problem with having a missing target for the glass relaxation process, since this metastable supercooled liquid state can always be defined.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): B. Grosdidier〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, a rigorous mathematical method to calculate the order parameter in a binary amorphous or liquid alloy, is established even when the alloy is made up of very differently sized atoms. This method, based on the study of the eigenstates of the exchange operator of the alloy components, allows revealing different spherical layers whose inner and outer radii are solutions of a certain equation. These layers have no constant thickness but contain numbers of atoms of each species that are exactly in the ratio of the concentrations of these two species. Thus, each layer has exactly the average concentration of the alloy, allowing to properly formalize the order parameter. Thus the order parameter is formalized in each of these layers. This method makes possible to retrieve the subtle Bhatia-Thornton formalism [Phys. Rev., B2, 3004 (1970)] used for the description of binary alloys. We discuss the link between the zero 〈em〉q〈/em〉 value of concentration-concentration Bhatia-Thornton partial structure factor and the numbers of neighbours. We apply our method to study the order in the Bi〈sub〉0.3〈/sub〉Ga〈sub〉0.7〈/sub〉 liquid alloy. We are able to determine eight layers and their order parameter on the interatomic distance-range [0, 15 Å].〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Hongtu He, Tongjin Xiao, Qian Qiao, Jiaxin Yu, Yafeng Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is well-known that the sliding contact damage of glass materials is very sensitive to the presence of water, but the detailed mechanisms remain elusive. In this work, the effects of water and speed on wear behaviors of soda lime silica (SLS) glass are investigated upon a ball-on-flat reciprocating tribometer in dry and humid air. When water molecules are present at the sliding interfaces in humid air, the wear volume of SLS glass decreases with the increase in sliding speed from 0.25 mm/s to 8 mm/s, which is believed to be originated from the suppressed tribochemical reactions involving water molecules at high speed conditions, therein the wear volume of SLS glass decreases to ~6 times. However, when water molecules are absent at the sliding interfaces in dry air, the wear volume of SLS glass increases to ~12.5 times when the sliding speed increases from 0.25 mm/s to 8 mm/s. Analyses suggest that the wear of SLS glass in dry air is dominated by the adhesive wear and brittle exfoliation, which can be facilitated by the friction-induced temperature rise and surface cracking at high speed conditions. Our results indicate that the sliding speed can either promote or suppress the wear of SLS glass, depending on the presence of water molecules at the sliding interfaces. These results may provide a deep understanding on the effects of water and speed on the material damage of oxide glass materials during its manufacturing and operation processes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): S.S. Chen, W.H. Li, X.R. Zeng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, an enhanced room-temperature plasticity was achieved in a Zr〈sub〉62.8〈/sub〉Cu〈sub〉15〈/sub〉Co〈sub〉9.2〈/sub〉Ti〈sub〉6〈/sub〉Al〈sub〉7〈/sub〉 glassy alloy through the application of micro-arc oxidation (MAO) treatment. After treated for 15 and 30 min, the glassy alloy specimen exhibited an enhanced plastic strain of 5.5% and 7.9%, respectively. Both the introduction of nucleation sites for shear band at the coating/substrate interface owing to stress concentration and the physical constraint effect for the propagating shear bands from the in-situ formed coating are responsible for the enhanced plasticity. This finding may open a new avenue for developing ductile metallic glasses from a surface modification aspect.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Zhuang Guo, Song Ye, Ping Xiao, Deping Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research, the Ag nanoclusters (Ag NCs) dispersed borosilicate glasses with the absence and presence of LiF were prepared by the melt-quenching method. The absorption, photoluminescence, FTIR results indicated that the doping of LiF plays dual effects on the size evaluation of Ag species: the introduction of F〈sup〉−〈/sup〉 and Li〈sup〉+〈/sup〉 can promote and restrain the formation of Ag NCs, respectively. It was also indicated that the promotion effect of F〈sup〉−〈/sup〉 is overwhelming at lower LiF doping concentration, while the restrain effect of Li〈sup〉+〈/sup〉 becomes dominated when increase LiF concentration to 8 mol%. Besides, our research further proved that the formation of Ag NCs is very sensitive to the presence of F content, even the introduction of rare earth ions in the form of fluoride or oxide can obviously modify the amount and size distribution of Ag NCs and thus affect the luminescence properties of the codoped glasses.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Zongwen Zhao, Yuxia Song, Xiaobo Min, Yanjie Liang, Liyuan Chai, Meiqing Shi〈/p〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Bo Huang, Changfu Xu, Zhen Zhang, Chun yang Zang, Lizhong Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The near ~3 μm mid-infrared laser demonstrates real and potential applications in many military and civilian areas, but the lack of host materials with nice optical quality and the overlapped vibrations of OH〈sup〉–〈/sup〉 hamper the emission intensity. To eliminate the OH〈sup〉–〈/sup〉 absorption, ZnF〈sub〉2〈/sub〉 was adopted in Yb〈sup〉3+〈/sup〉/Ho〈sup〉3+〈/sup〉 codoped binary TeO〈sub〉2〈/sub〉-PbF〈sub〉2〈/sub〉 glass to partially till totally replace PbF〈sub〉2〈/sub〉. The high ZnF〈sub〉2〈/sub〉 concentration would raise the glass transition temperature and enhance the thermal stability of matrix, especially enhance the intensity of 2.85 μm mid-infrared luminescence obviously. TeO〈sub〉2〈/sub〉-ZnF〈sub〉2〈/sub〉 glass with 45.5% ZnF〈sub〉2〈/sub〉 original content has high ratio of the strength parameter 〈em〉Ω〈/em〉〈sub〉〈em〉4〈/em〉〈/sub〉〈em〉/Ω〈/em〉〈sub〉〈em〉6〈/em〉〈/sub〉 (=2.90) and possesses higher spontaneous transition probability (45.25 S〈sup〉−1〈/sup〉) along with the larger calculated emission cross section (0.96 × 10〈sup〉−20〈/sup〉 cm〈sup〉2〈/sup〉) corresponding Ho〈sup〉3+〈/sup〉: 〈sup〉5〈/sup〉I〈sub〉6〈/sub〉 → 〈sup〉5〈/sup〉I〈sub〉7〈/sub〉 transition. Fourier transmittance of infrared spectra revealed ZnF〈sub〉2〈/sub〉 could reduce the OH〈sup〉–〈/sup〉 concentration in glass substantially, which were favor of 2.85 μm mid-infrared emission. Our results indicated that the use of ZnF〈sub〉2〈/sub〉 to effectively remove the hydroxyl groups is an efficacious way to develop near ~3 μm mid-infrared optical glass with high efficient luminescence and thermochemical reliability.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Ana F. Kozmidis Petrović, Goran R. Štrbac, Dragana D. Štrbac〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this paper, the modified Kissinger equation and the Ozava type equation were obtained by using a process of homogenization from dimensional analysis, thus making them correct in relation to the application of a logarithmic function. An equation that holds at maximum reaction rate is applied for the chosen reference heating rate 〈em〉β〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 and also for a heating rate 〈em〉β〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 that was used. In that way the modified Kissinger equation 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="block" altimg="si1.gif" overflow="scroll"〉〈mo〉ln〈/mo〉〈mfenced open="(" close=")"〉〈mrow〉〈mfrac〉〈msubsup〉〈mi〉T〈/mi〉〈mi mathvariant="italic"〉mr〈/mi〉〈mn〉2〈/mn〉〈/msubsup〉〈msubsup〉〈mi〉T〈/mi〉〈mi mathvariant="italic"〉mi〈/mi〉〈mn〉2〈/mn〉〈/msubsup〉〈/mfrac〉〈mfrac〉〈msub〉〈mi〉β〈/mi〉〈mi〉i〈/mi〉〈/msub〉〈msub〉〈mi〉β〈/mi〉〈mi〉r〈/mi〉〈/msub〉〈/mfrac〉〈/mrow〉〈/mfenced〉〈mo〉=〈/mo〉〈mo〉−〈/mo〉〈mfrac〉〈mi〉E〈/mi〉〈mi〉R〈/mi〉〈/mfrac〉〈mfrac〉〈mn〉1〈/mn〉〈msub〉〈mi〉T〈/mi〉〈mi mathvariant="italic"〉mi〈/mi〉〈/msub〉〈/mfrac〉〈mo〉+〈/mo〉〈mfrac〉〈mi〉E〈/mi〉〈mi〉R〈/mi〉〈/mfrac〉〈mfrac〉〈mn〉1〈/mn〉〈msub〉〈mi〉T〈/mi〉〈mi mathvariant="italic"〉mr〈/mi〉〈/msub〉〈/mfrac〉〈/math〉 was obtained. The modified Ozava type equation was obtained in the form.〈/p〉 〈p〉〈span〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mo〉ln〈/mo〉〈mfenced〉〈mfrac〉〈msub〉〈mi〉β〈/mi〉〈mi〉i〈/mi〉〈/msub〉〈msub〉〈mi〉β〈/mi〉〈mi〉r〈/mi〉〈/msub〉〈/mfrac〉〈/mfenced〉〈mo〉=〈/mo〉〈mo〉−〈/mo〉〈mfrac〉〈mrow〉〈mi〉m〈/mi〉〈mi〉E〈/mi〉〈/mrow〉〈mrow〉〈mi〉n〈/mi〉〈mi〉R〈/mi〉〈/mrow〉〈/mfrac〉〈mfrac〉〈mn〉1〈/mn〉〈msub〉〈mi〉T〈/mi〉〈mi mathvariant="italic"〉mi〈/mi〉〈/msub〉〈/mfrac〉〈mo〉+〈/mo〉〈mfrac〉〈mrow〉〈mi〉m〈/mi〉〈mi〉E〈/mi〉〈/mrow〉〈mrow〉〈mi〉n〈/mi〉〈mi〉R〈/mi〉〈/mrow〉〈/mfrac〉〈mfrac〉〈mn〉1〈/mn〉〈msub〉〈mi〉T〈/mi〉〈mi mathvariant="italic"〉mr〈/mi〉〈/msub〉〈/mfrac〉〈/math〉〈/span〉where 〈em〉T〈/em〉〈sub〉〈em〉mr〈/em〉〈/sub〉 and 〈em〉T〈/em〉〈sub〉〈em〉mi〈/em〉〈/sub〉 are the temperatures of the maximum obtained with 〈em〉β〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 and 〈em〉β〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 respectively. In these equations, free terms are explicitly defined and from their values it is possible to calculate the value of activation energy 〈em〉E〈/em〉, as from the slope of straight lines. The main advantage of the modified equations compared to the original Kissinger equation and the Ozava type equation is not the more accurate value of the activation energy, but the more precise form of the equation.〈/p〉 〈p〉With the goal to overcome all imperfections of the Lasocka equation, we propose the modified relationship 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 〈em〉= A〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 〈em〉+ B〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 log〈em〉(β/β〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 〈em〉+〈/em〉 〈em〉1)〈/em〉 between the glass transition temperature 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 and the heating rate 〈em〉β〈/em〉. In this equation, the logarithm is calculated from dimensionless values, where 〈em〉β〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 is the chosen reference heating rate. In contrast to the original Lasocka equation, the modified Lasocka equation parameters 〈em〉A〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 and 〈em〉B〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 have the same units. The temperature 〈em〉T〈/em〉〈sub〉〈em〉g0〈/em〉〈/sub〉 = 〈em〉A〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 can be obtained by extrapolation of experimental results to 〈em〉β〈/em〉 = 0. This is impossible to get from the original Lasocka equation, but it can be obtained from the modified one.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Collin J. Wilkinson, Evgeny Pakhomenko, Martha R. Jesuit, Anthony DeCeanne, Brittney Hauke, Michael Packard, Steve A. Feller, John C. Mauro〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A topological constraint model is developed to elucidate the coordination environment of alkali tellurite glasses. The model is derived from temperature-dependent constraint theory and provides a quantitative connection between the connectivity of the glass network and the compositional dependence of the glass transition temperature (〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉). Our model gives support to the model proposed by Barney et al. [〈em〉J. Phys. Chem. Lett.〈/em〉〈strong〉4,〈/strong〉 2312–2316 (2013)], confirming their model of the coordination environment in alkali tellurites. The model simultaneously serves as a framework that can be used in binary alkali glass-formers to predict an expected coordination the network forming cation in an oxide glass.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Yasuhiro Nobuta, Yoshihiro Takahashi, Takamichi Miyazaki, Nobuaki Terakado, Noriko Onoue, Tsuyoshi Shinozaki, Takumi Fujiwara〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recently, we have developed the borosilicate glass, in which ZrO〈sub〉2〈/sub〉 phase is singly crystallizable, and has found an emissive monoclinic ZrO〈sub〉2〈/sub〉 dendrites in the resulting GCs. In order to promote the formation of monoclinic phase, we have examined the effect of substitution of alumina Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 for ZrO〈sub〉2〈/sub〉 in the precursor glass composition, i.e., 15Na〈sub〉2〈/sub〉O–(15 − 〈em〉x〈/em〉)ZrO〈sub〉2〈/sub〉–〈em〉x〈/em〉Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–30B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–40SiO〈sub〉2〈/sub〉. It was found that the substitution of small amount of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (〈em〉x〈/em〉 = 1) gave a positive effect, i.e., increase in the amount of monoclinic phase and decrease in the crystal size. Furthermore, the substitution improved the internal quantum-yield. On the other hand, the further substitution (〈em〉x〈/em〉 ≥ 2) provided the decrease in amount of the monoclinic phase.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Takumi Kato, Go Okada, Noriaki Kawaguchi, Hirokazu Masai, Takayuki Yanagida〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have investigated photoluminescence (PL) and scintillation properties of 30BaO-15TiO〈sub〉2〈/sub〉-(55-〈em〉x〈/em〉)GeO〈sub〉2〈/sub〉-〈em〉x〈/em〉SiO〈sub〉2〈/sub〉 (BTGS〈em〉x〈/em〉: 〈em〉x〈/em〉 = 0, 13.75, 25, 30, 41.25 and 55) glasses and glass-ceramics prepared by the conventional melt-quenching method. In the PL spectra of all the samples, an emission band was observed around 490 nm. In addition, another emission band was detected around 530 nm in the BTGS30, BTGS25, BTGS13.75 and BTG55 glass-ceramics. From the PL decay time constants, the emission bands at 490 and 530 nm were confirmed to be due to the 〈sup〉3〈/sup〉T〈sub〉1〈/sub〉-〈sup〉1〈/sup〉A〈sub〉1〈/sub〉 transition of Ti〈sup〉4+〈/sup〉 ions and 〈sup〉2〈/sup〉E-〈sup〉2〈/sup〉T〈sub〉2g〈/sub〉 transition of Ti〈sup〉3+〈/sup〉 ions, respectively. The quantum yields of all the glass-ceramics were higher than those of the glasses of the same chemical compositions. In scintillation spectra, all the samples showed emission peaks similarly seen in PL. The scintillation intensities of the glass-ceramics were higher than those of the glasses of the same chemical compositions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Dmytro Savytskii, Volkmar Dierolf, Nobumichi Tamura, Himanshu Jain〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have investigated the occurrence of the sometimes observed grain boundaries, as initial seed is extended to form line in laser-fabricated single-crystal architecture in glass (SCAG). In particular, for Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 SCAG in Sb-S-I glass as a model system, grain boundaries are formed during the transition from laser-written initial seed dot to crystal line. Such grain boundaries during the growth of Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 crystals occur in 16SbI〈sub〉3〈/sub〉–84Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 glass, whereas they are absent in Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 glass. We correlate this difference in tendency to form multiple grains with the relative glass forming ability i.e. the dynamics of nucleation and crystal growth as determined by differential scanning calorimetry (DSC). On the basis of this understanding, methods to minimize the appearance of grain boundaries in the transition region are suggested.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Go Okada, Kenji Shinozaki, Takayuki Komatsu, Naoki Kawano, Noriaki Kawaguchi, Takayuki Yanagida〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tb〈sup〉3+〈/sup〉-doped BaF〈sub〉2〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 glass and glass-ceramic were synthesized, and the luminescence properties were investigated for potential applications in radiation measurements. The glass-ceramic can be obtained by heat-treating the glass, and it includes BaAlBO〈sub〉3〈/sub〉F〈sub〉2〈/sub〉 crystalline phase in glass matrix. The photoluminescence (PL) quantum yield is higher for glass than glass-ceramic. The reason can be due to the difference of the number of F〈sup〉−〈/sup〉 and O〈sup〉2–〈/sup〉 ions surrounding Tb〈sup〉3+〈/sup〉 activator ion. The lifetime of PL is slightly shorter than that of scintillation suggesting energy transfer process from the host to Tb〈sup〉3+〈/sup〉 is involved. The time-response of scintillation has significantly slow rise feature possibly due to excited state absorption. Both glass and glass-ceramic show efficient optically-stimulated luminescence (OSL) with equivalent sensitivities despite the large difference of PL efficiency. The latter observation suggests that the glass-ceramic includes large number of OSL active centres than glass. The OSL dynamic range was confirmed to be at least 10〈sup〉1〈/sup〉–10〈sup〉4〈/sup〉 mGy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Sergey I. Gutnikov, Yuriy V. Pavlov, Evgeniya S. Zhukovskaya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of low-frequency vibrational treatment on the crystallization of basalt wool fibers was studied. In this work, three series of samples were investigated. The first sample set was only one-sided heated at temperatures from 300 °C to 900 °C for 24 h. The second sample set was after only vibrational treatment with a frequency of 50 Hz and oscillations amplitude of 1 mm for 6–48 h. The third sample set was after simultaneous treatment of one-sided heating and vibration at temperatures from 300 °C to 600 °C with a frequency of 50 Hz and oscillations amplitude of 1 mm for 24 h. It is shown that at temperatures close to the glass transition temperature, vibration can influence on the relaxation processes in glasses and accelerate them. Mechanism of glass structure transformation in the basalt fiber does not change, but it starts at a slightly lower temperature. That is a consequence of an additional low-energy vibrational treatment. The vibrational treatment intensifies the crystallization process in basalt fibers and decreases the service temperature of the material by at least 40–50 °C.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Jürn W.P. Schmelzer, Alexander S. Abyzov〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In classical nucleation theory, the thermodynamic driving force of crystallization is computed by comparing the bulk properties of the liquid and crystal phases for the respective macroscopic samples. Such approach represents a reasonable approximation as far as the bulk properties of the critical clusters do not deviate significantly from the properties of the newly evolving macroscopic phases. However, in general, this assumption is not true and may lead to incorrect results. As one consequence, the classical approach utilizing, in addition, the capillarity approximation overestimates as a rule the work of critical cluster formation and underestimates the steady-state nucleation rate. Based on a generalization of the classical Gibbs’ approach, the basic equations are formulated here allowing one a correct determination of the properties of the critical clusters and of the work of critical cluster formation. In this way, a new tool for the quantitative description of crystal nucleation has been advanced retaining the advantages of the classical treatment but avoiding its shortcomings. Several general consequences are discussed. In particular, it is demonstrated that this method opens a new perspective in the interpretation of possible effects of atomic-scale structure of the melts on the rate of crystal nucleation.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volumes 503–504〈/p〉 〈p〉Author(s): Guang Wang, Yingchun Shan, Jianxin Xu, Yuzhen Chen, Jiujun Xu, Jiangtao Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉By formation β-SiAlON/Y-Si-Al-O-N glass-ceramic as interlayer, AlON ceramics (51.70 at.% O) were successfully joined at 1475 °C for 15 min. The effects of joining temperature on wettability of interlayer material on AlON ceramics, phase assemblages and microstructures of joints, and bending strength of the as-joined AlON ceramics were investigated. The wettability of the interlayer material on the AlON ceramics is positively correlated with joining temperature at 1300–1475 °C, and the minimum contact angle of 8° was measured at 1475 °C. Increasing joining temperature is helpful to improve the bonding strength, and the maximum bending strength of 125 MPa was achieved for the samples joined at 1475 °C, which is ~41.7% of AlON strength. The high bonding strength should be mainly attributed to the formation of high strength β-SiAlON crystalline in Y-Si-Al-O-N glasses and strong interface between AlON substrate and interlayer led by the excellent wettability of β-SiAlON/Y-Si-Al-O-N glass-ceramic on AlON ceramics.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volumes 503–504〈/p〉 〈p〉Author(s): Hristo Aleksandrov Solunov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The molecules of the supercooled liquids in the cooperative molecular dynamics are partitioning to specific dynamic units, known as “beads”. The beads have been defined as the smallest units, forming the heat capacity of the supercooled liquids. The beads appear as a sub-molecular scale in the dynamics of the glass-forming liquids. In the Adam-Gibbs theory the number of molecules, rearranging simultaneously, has been defined as the size of the cooperative rearranging region and these regions form the second larger molecular scale in molecular dynamics. Due to a noticeable discrepancy in estimating the number of beads in the molecules by the empirical rules as well as by theoretical models the relations between these two scales are not well known. Recently, a new thermodynamic method for estimating the number of the beads in the molecules and a rule for the examination of their temperature dependence have been suggested. By these methods 48 low-molecular supercooled liquids are investigated and the relations between these two molecular scales and the structure of the molecules have been found. The estimated number of configuration beads is compared with the number of the structural units (the chemical groups, the ions and the atoms), with the assigned number by the empirical rules and with the ones calculated, based on a Lennar-Jones model of the random first order transition theory. A constant and two kinds of temperature dependence of the number of the beads in the molecules of different liquids have been revealed. A molecular basis, forming the fragility of the supercooled liquids, has been found. From the results obtained, the investigated liquids are classified in several groups following the logical line in the formation of the beads.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 502〈/p〉 〈p〉Author(s): Jung-Chang Kung, Yi-Jhen Chen, Yu-Ching Chiang, Chung-Lin Lee, Yuan-Ting Yang-Wang, Chun-Cheng Hung, Chi-Jen Shih〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Many clinical cases show that the failure of root-canal treatment is primarily attributable to remnants of bacteria in root canal systems, especially 〈em〉Enterococcus faecalis〈/em〉 (〈em〉E. faecalis〈/em〉).〈/p〉 〈p〉In this study, silver nanoparticle (AgNP) confined mesoporous structured bioactive powder (M-BP-Ag) was prepared by the evaporation-induced self-assembly (EISA) method and evaluated for antibacterial activity against 〈em〉E. faecalis〈/em〉. The composition of the M-BP-Ag belongs to the SiO〈sub〉2〈/sub〉-CaO-P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 system. The M-BP-Ag was obtained with the composition ratios of Si, Ca, P, and Ag in mole% being (80-X), 15, 5, and X, where X = 0, 1, 5, or 10, respectively. X-ray diffraction (XRD), gas adsorption and desorption analyzer, and transmission electron microscopy (TEM) were used to characterize these M-BP-Ag.〈/p〉 〈p〉The antibacterial activity of the test samples against 〈em〉E. faecalis〈/em〉 was verified by the time-killing curve test and the colony-forming capacity assay. The samples' antibacterial activities depended on the confined AgNP position. From bacterial morphology observation, we also speculated the antibacterial mechanism of the M-BP-Ag test samples in this study.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 501〈/p〉 〈p〉Author(s): Mark J. Davis, Paula Vullo, Michaelene Kocher, Martun Hovhannisyan, Martin Letz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report on a non-ferroelectric, piezoelectric polar glass-ceramic specifically targeted for high-temperature sensor use (〈em〉T〈/em〉 〉 300 °C). Potential applications include accelerometers for turbine engines and in-cylinder pressure sensors for diesel engines. Choice of an alkali-free, Sr-fresnoite (Sr〈sub〉2〈/sub〉TiSi〈sub〉2〈/sub〉O〈sub〉8〈/sub〉) + added SiO〈sub〉2〈/sub〉 bulk composition led to desirably high electrical resistivity while maintaining good piezoelectric sensitivity. Piezoelectric properties are highly competitive with existing high-temperature single crystals and ceramics, consisting of 〈em〉d〈/em〉〈sub〉33〈/sub〉 = 10, 〈em〉d〈/em〉〈sub〉31〈/sub〉 = 1.5, and 〈em〉d〈/em〉〈sub〉15〈/sub〉 = 34 (pC/N). Support for the high value of the shear mode 〈em〉d〈/em〉〈sub〉15〈/sub〉 coefficient comes from both direct measurement as well as consideration of the expected variation in effective 〈em〉d〈/em〉〈sub〉33〈/sub〉 due to deviation in perfect (001) crystalline alignment, as demonstrated in this system by Wisniewski et al. (2012). Due to the low dielectric permittivity in this system (〈em〉ε〈/em〉〈sub〉33〈/sub〉〈sup〉〈em〉T〈/em〉〈/sup〉/〈em〉ε〈/em〉〈sub〉0〈/sub〉 = 11.5; 〈em〉ε〈/em〉〈sub〉11〈/sub〉〈sup〉〈em〉T〈/em〉〈/sup〉/〈em〉ε〈/em〉〈sub〉0〈/sub〉 = 16.5, both at 1 kHz), the voltage coefficients are quite high: 〈em〉g〈/em〉〈sub〉33〈/sub〉 = 103, 〈em〉g〈/em〉〈sub〉31〈/sub〉 = 15, and 〈em〉g〈/em〉〈sub〉15〈/sub〉 = 233 (×10〈sup〉−3〈/sup〉 V m/N). The room-temperature pyroelectric coefficient 〈em〉p〈/em〉〈sub〉3〈/sub〉 of +8 μC/m〈sup〉2〈/sup〉/°C is followed by a hysteretic peak, though repeatable, near 175 °C, attaining −70 μC/m〈sup〉2〈/sup〉/°C, but by 250 °C, 〈em〉p〈/em〉〈sub〉3〈/sub〉 has returned to low levels and passes through zero around 275 °C. Of crucial particular importance for high-temperature applications is high electrical resistivity, well exemplified by this material, with 〈em〉ρ〈/em〉 ~ 10〈sup〉12〈/sup〉 Ω-cm at 300 °C and 10〈sup〉6〈/sup〉 at 850 °C; higher levels of resistivity can be obtained through use of raw materials with lower levels of alkali contaminants. The combination of high electrical resistivity coupled with good piezoelectric sensitivity and the lack of a Curie temperature, with its associated aging effects, makes Sr-fresnoite glass-ceramics a realistic contender in the technically-challenging field of high-temperature piezoelectric materials.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volumes 503–504〈/p〉 〈p〉Author(s): W.C. Wang, Y.B. Xiao, B. Zhou, S.H. Xu, Q.Y. Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The structural, thermal, and luminescent properties of germanate glass containing heavily Dy〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content are systematically investigated by means of differential scanning calorimetry, X-ray diffraction, Raman spectra, absorption and emission spectra, and dynamic lifetime decay curves. To seek a suitable composition, the optimal glass forming region is first predicted through the thermodynamic calculation method and their basic physical properties are further forecasted according to the phase diagram model. The experiment results show that the density, refractive index, characteristic temperature, and phonon energy of the glass host all exhibit a close connection with the rare earth concentration. Strikingly, when the amount of Dy〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is up to 10.5 mol%, the transition temperature of the glass reaches 747 °C, which is higher than any other known germanate glass and is much advantageous to achieve a higher laser damage threshold. Moreover, the high doping caused the refractive index to increase significantly, which also prompted the glass to obtain a larger emission section and quality factor, increasing the possibility of laser output. Besides, three visible luminescence peaks of Dy〈sup〉3+〈/sup〉 at 480 nm (blue) and 575 nm (yellow), and 665 nm (red) are observed even at an extremely high Dy〈sup〉3+〈/sup〉 concentration. All the results demonstrate that this kind of germanate glass containing significant amounts of RE could be of interest for implementation of high-gain fiber lasers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Young Hoon Rim, Mac Kim, Jae-Hyeon Ko, Yong Suk Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have studied the relationship between ionic conductivity and the ionic radius of A site in 2AO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉2TiO〈sub〉2〈/sub〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉SiO〈sub〉2〈/sub〉 (ATSO; A〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉Ca, Sr and Ba) glasses. Electrical measurements were carried out in the frequency range 100 Hz ~ 30 MHz and temperature range 300–540 °C. Raman spectroscopy and differential thermal analysis measurements were also performed. The exponents of the Cole-Cole plot, power-law conductivity and modulus formalisms reveal the nature of ionic transport and the conductivity relaxation. Raman spectroscopic data of ATSO glasses clarify the modification of vibrational networks of silicate and titanate complexes by alkaline-earth metals (Ca, Sr and Ba). The ratio of non-bridging oxygens per tetrahedrally coordinated cations (NBO/T) in the 2CaO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉 and 2SrO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉2TiO〈sub〉2〈/sub〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉SiO〈sub〉2〈/sub〉 glasses decreases rapidly, suggesting polymerization of the silicate and titanate networks. The disorder of the glass matrix in 2BaO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉2TiO〈sub〉2〈/sub〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉SiO〈sub〉2〈/sub〉 glass is greatly reduced with increasing non-bridging oxygens per NBO/T and decreasing interionic Coulomb interactions. The conduction mechanisms of 〈em〉dc〈/em〉 and 〈em〉ac〈/em〉 for all ATSO glasses are the same but the ions hop through a different fractal structured conduction pathway. The dimension of ionic conduction pathway decreases with increasing ionic radius of alkaline-earth metals in ATSO glasses.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): K. Ullmann, P. Ádám, K. Sinkó〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work a new low-cost sol-gel method has been developed to prepare highly porous alumina systems. The prime consideration of this research work was to avoid the complicated and laborious preparation technique and the expensive drying processes. Aluminum oxide hydroxide gel systems were synthesized by a new sol-gel route. The sol-gel process starts from only two chemical compounds; from an aluminum salt and a solvent, and it does not adopt any basic agent or complex formation. All gel systems were dried at atmospheric pressure to obtain xerogels. Different chemical agents (such as gelation agent propylene oxide, surfactant characteristic citric acid and ethyl acetate or basic agent carbamide and urotropine) were applied. Their application was varied in the steps of the sol-gel procedure. Some wet gels were subjected to different treatments (microwave radiation and freezing in vacuum) before the drying process. The cryogels evolved by lyophilization was provided for the comparison. The route of propylene oxide’ addition to system reacted for 24 h produces a bead-like structure with the highest porosity and smallest pores in the present work.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Ting Zhou, Lunlun Gong, Xudong Cheng, Yuelei Pan, Congcong Li, Heping Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The by-product silicon tetrachloride (SiCl〈sub〉4〈/sub〉) was usually obtained from polysilicon industry and was a cheaper alternative precursor. An economic method to produce silica aerogel using silicon tetrachloride under ambient pressure drying was presented in this work, which can also solve the pollution problem during the by-product silicon tetrachloride treatment process. The prepared aerogel samples were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, thermal conductivity analysis, contact angle test, Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found that the molar ratio of H〈sub〉2〈/sub〉O/SiCl〈sub〉4〈/sub〉 could affect the properties of aerogels seriously. The density and thermal conductivity first decreased and then increased as the molar ratio increased from 13 to 32. The porosity showed an opposite trend with the density. Silica aerogel with high specific surface area (856.7 m〈sup〉2〈/sup〉/g), low density (0.077 m〈sup〉3〈/sup〉/g) and low thermal conductivity (0.0213 W/m·k) were obtained at the optimal conditions when the molar ratio was 25. The resulting aerogel is also mesoporous material with super hydrophobicity and have a huge application in thermal insulation field.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Janis Snikeris, Vjaceslavs Gerbreders, Valdis Mizers〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electron beam (EB)-induced deformations of the surface of thin Cr films on soda-lime glass and Si substrates were studied using atomic force microscopy. The thickness of the Cr films was within the range 20 to 500 nm. The thin films were irradiated with a 30 keV EB in the vacuum chamber of a scanning electron microscope. The EB current was within the range 10 pA to 15 nA, and the irradiation time was within the range 30 s to 10 min. The lateral size of the deformations was typically at the micrometre scale, while their vertical size was at the sub-micron and nanometre scales. Depressions of up to 80 nm deep and bulges of up to 700 nm high were observed. Irradiated areas were wet etched using K〈sub〉3〈/sub〉[Fe(CN)〈sub〉6〈/sub〉] in an alkaline solution. It was observed that EB irradiation can significantly decrease the etching rate and that wet etching can increase the height to width ratio of EB-induced deformations on Cr thin films. Possible physical mechanisms for formation of these deformations are discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Sean W. King, Liza Ross, William A. Lanford〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Intermediate phases represent the so called “sweet spot” in amorphous material systems where the bond stretching and bond bending constraint forces are equally balanced by the total degrees of freedom in the system. They are sometimes also referred to as “Boolchand” phases in recognition of the seminal contributions of Dr. Punit Boolchand to the study of these materials. In a prior publication (King et al., 〈em〉J. Non-Cryst. Solids〈/em〉 379 (2013) 67), we presented possible evidence for the existance of an intermediate (i.e. “Boolchand”) phase in amorphous hydrogenated silicon carbide (a-SiC:H) with a wide range in mean atomic coordination (〈〈em〉r〈/em〉〉 = 2.4 − 2.7). Support for such a wide phase window was based primarily on a correlation between the post plasma deposition bi-axial film stress and 〈〈em〉r〈/em〉〉. However, we demonstrate in the present article that the apparent width of the Boolchand intermediate phase window in the prior study was inflated due to two competing film stress contributions, and that the true range in 〈〈em〉r〈/em〉〉 for the phase window is substantially narrower. Specifically, opposing tensile and compressive film stress components were identified to arise during the plasma enhanced chemical vapor deposition (PECVD) of a-SiC:H. The tensile film stress component was attributed to film/substrate thermal contraction mismatch on cooling from the deposition temperature, while the compressive stress component was attributed to ion bombardment of the a-SiC:H growth surface during PECVD. In the prior study, the energy of the ions during PECVD was primarily modulated by the addition of a low frequency bias to the plasma and was intentionally utilized to produce films with varying compressive stress and 〈〈em〉r〈/em〉〉. In the present study, the low frequency bias was removed from the PECVD of a-SiC:H and instead the deposition pressure was varied to produce films with varying 〈〈em〉r〈/em〉〉 and exclusively tensile stress. Through detailed analysis of the tensile bi-axial film stress and Young's modulus dependence on 〈〈em〉r〈/em〉〉, we found conclusive evidence that the film-substrate thermal contraction mismatch was the dominant film stress component in this case and that the magnitidue of the tensile stress was purely due to rigidity percolation in the a-SiC:H film. We therefore conclude that in our previous study the balance of the tensile and compressive stress components resulted in the deceptive appearance of a potentially wide Boolchand intermediate phase window for a-SiC:H. Based on the a-SiC:H films generated in the present study where only the tensile stress component was significant, we have found the window for a possible intermediate phase to be greatly narrowed at Δ〈〈em〉r〈/em〉〉 ≤ 0.05.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): C. Dong, A. Inoue, X.H. Wang, F.L. Kong, E.N. Zanaeva, F. Wang, A.I. Bazlov, S.L. Zhu, Q. Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the aim of developing a new inexpensive soft magnetic amorphous alloy exhibiting high saturation magnetic flux density (〈em〉B〈/em〉〈sub〉s〈/sub〉) above 1.7 T, we examined the formation, thermal stability and magnetic properties for melt-spun Fe-B-Si-C amorphous alloys with high (B + C)/Si content ratios. The high 〈em〉B〈/em〉〈sub〉s〈/sub〉 of 1.71–1.73 T exceeding the previously reported 〈em〉B〈/em〉〈sub〉s〈/sub〉 was obtained for annealed Fe〈sub〉82-82.5〈/sub〉B〈sub〉15〈/sub〉Si〈sub〉2〈/sub〉C〈sub〉0.5-1〈/sub〉 alloys. These high 〈em〉B〈/em〉〈sub〉s〈/sub〉 alloys exhibit low coercivity below 8 A/m and good bending ductility. The 82.5Fe alloy with the highest 〈em〉B〈/em〉〈sub〉s〈/sub〉 of 1.73 T also has the highest hardness. Besides, the 82.5Fe alloy has the largest nearest neighbor atomic distance among the present alloys. The correlation between the highest 〈em〉B〈/em〉〈sub〉s〈/sub〉 and the largest atomic distance is similar for (Fe,Co)〈sub〉83-86〈/sub〉B〈sub〉15-16〈/sub〉Si〈sub〉1〈/sub〉 amorphous alloys. The 82.5Fe and 82Fe alloys are located near the critical composition where the crystallization changes from two stages of α-Fe(Si) + amorphous ⇢ α-Fe(Si) + Fe〈sub〉3〈/sub〉(B,C) to a single stage of α-Fe(Si) + Fe〈sub〉3〈/sub〉(B,C). These results indicate the importance of the special alloy composition with the largest atomic distance and high stability to primary α-Fe precipitation, in addition to high (B + C)/Si content ratios, for the synthesis of a new ductile amorphous alloy with high 〈em〉B〈/em〉〈sub〉s〈/sub〉 and good magnetic softness.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Akira Takada〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Packing models have been used as one of powerful analytical tools to investigate atomic structures comprised of single element or metallic alloy. In this study, the structures of SiO〈sub〉2〈/sub〉 crystals and glasses were studied by a new packing model. To deal with two-element oxide systems like SiO〈sub〉2〈/sub〉, packing structures focused only on oxygen atoms were constructed using the Voronoi tessellation method. First, the method was applied to crystal polymorphs of SiO〈sub〉2〈/sub〉. Species of polyhedron, species of polygon and volume of each polyhedron were compared between the polymorphs. The calculated results captured not only structure features inherent in each crystal, but also the indication of structural changes such as α–β transition or corruption of crystal structure. Next, the method was applied to SiO〈sub〉2〈/sub〉 glass. The Voronoi analysis distinguished glass from crystals in terms of species of polyhedron. In addition, the same method could distinguish structural changes caused by thermal effects from those by pressure effects. The thermal effects change geometrical symmetry (i.e. shape of polyhedron and polygon) with little change in Voronoi volume, in contrast, the pressure effects change geometrical symmetry less with larger change in Voronoi volume. In addition, a new index, which represents a degree of geometrical similarity between crystals and glasses, was defined in terms of Voronoi polyhedron. In sum, the Voronoi analysis based on oxygen packing is expected to be a promising tool to investigate not only the structure of crystal polymorphs but also that of glass and liquid, taking the complimentary role to the conventional network model.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): Joao F.V.L. Munhoz, Silvia Helena Santagneli, Marcos de Oliveira, Ana Candida Martins Rodrigues, Hellmut Eckert, Marcelo Nalin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxyfluoride glasses with composition 〈em〉x〈/em〉 WO〈sub〉3〈/sub〉 - 30 NaPO〈sub〉3〈/sub〉 - (70-〈em〉x〈/em〉) NaF, with 30 ≤ 〈em〉x〈/em〉 ≤ 70 were prepared by melt-quenching and characterized with respect to their bulk physical properties and ionic conductivities. As the NaF content increases, the glass transition temperature, 〈em〉T〈/em〉〈sub〉g〈/sub〉, decreases systematically. Impedance measurements reveal no clear effect of NaF content upon room temperature electrical conductivities and activation energies. There is, however, a significant decrease of the Arrhenius pre-exponential factor with increasing WO〈sub〉3〈/sub〉 content, suggesting that the electrical conductivities measured in this glass series are increasingly influenced by an electronic contribution. This contribution may be related to a W〈sup〉5+〈/sup〉 → W〈sup〉6+〈/sup〉 electron hopping process detected in the optical absorption spectra. Detailed spectroscopic investigations by Raman scattering and multinuclear one- and two-dimensional solid-state NMR experiments indicate that NaF acts like a network modifier resulting in the formation of W-F bonds via breakage of W-O-W and W-O-P linkages, with the former process being the preferred one. The concomitant decrease in network connectivity caused by these processes accounts for the experimentally observed decrease in glass transition temperatures with increasing NaF contents.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): V.G. Lebedev, A.A. Obukhov, M.G. Vasin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We show that in a binary solution in the presence of liquid phase of non-permanent composition, and a stoichiometric phase, for solute concentration exceeding some critical value, the instability mathematically described by the Cahn–Hilliard type equation can develop. Within the framework of the model system a dispersion relation is constructed. This relation allows to determine the concentration fluctuations dependence on time, and to investigate dynamics of structural factor and of amplification rate. The observed instability can explain the processes of slow non-monotonic relaxation in the glass-forming metal melts upon melting.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): Kyong-Soo Hong, Miae Kim, Myoung Gyu Ha, Jong Pil Kim, Jang-Hee Yoon, Jong Hwa Kim, Ho-Soon Yang, Hyun Gyu Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transparent glass of 〈em〉x〈/em〉Eu〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(100-〈em〉x〈/em〉)TeO〈sub〉2〈/sub〉 binary system is obtained by using the melt-quenching method and especially studied for 〈em〉x〈/em〉 = 5 in 〈em〉x〈/em〉Eu〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(100-〈em〉x〈/em〉)TeO〈sub〉2〈/sub〉 composition. Optical properties such as transmission, excitation, and emission spectra of Eu〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-TeO〈sub〉2〈/sub〉 glass-ceramics are studied and carefully compared for the samples heated at different temperatures. The one step heat-treatment affects the crystallinities as well as phase formation and yields cubic [Eu〈sub〉2〈/sub〉Te〈sub〉6〈/sub〉O〈sub〉15〈/sub〉], orthorhombic [TeO〈sub〉2〈/sub〉], and tetragonal [TeO〈sub〉2〈/sub〉] phases depending on the heat treating temperature. Glass-ceramics of Eu〈sup〉3+〈/sup〉-doped tetragonal [TeO〈sub〉2〈/sub〉] shows stronger emission intensity at wavelength of 613 nm with an excitation wavelength of 394 nm compared with that from cubic [Eu〈sub〉2〈/sub〉Te〈sub〉6〈/sub〉O〈sub〉15〈/sub〉] or Eu〈sup〉3+〈/sup〉-doped orthorhombic [TeO〈sub〉2〈/sub〉]. Enhancement of emission intensity in Eu〈sup〉3+〈/sup〉-doped tetragonal [TeO〈sub〉2〈/sub〉] is related to the local environment of Eu〈sup〉3+〈/sup〉 ions substituted in tetragonal TeO〈sub〉2〈/sub〉 lattice.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): Alesh Kumar, C.R. Mariappan, B.S. Sarahan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structural, electrical, bioactivity and antibacterial properties of mesoporous Ag doped calcium borosilicate glass-ceramics are reported. A simple sol-gel route was used to synthesize the mesoporous glass-ceramics. N〈sub〉2〈/sub〉 adsorption–desorption studies reveal the mesoporous structure of the samples. The embedment of nano-sized Ag metallic particles in glass matrix was confirmed for Ag doped sample calcined at 600 °C by X-ray diffraction, UV–visible, and transmission electron microscopic analyses. Ac conductivity is used to study the electrical relaxation processes. Ag nanoparticle-embedded sample reveal nearly constant loss behaviour, whereas silver ions alone embedded sample show universal dielectric relaxation behaviour. Ag doped samples exhibit good antibacterial properties without compromising the bone-like apatite layer formation. The antibacterial effect against Gram negative bacteria is higher for Ag doped sample calcined at 600 °C which exhibits a dominant nearly constant dielectric loss feature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): Shiva Naseri, William C. Lepry, Vimal B. Maisuria, Nathalie Tufenkji, Showan N. Nazhat〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Borate glasses have gained attention in wound healing applications attributable to their lower chemical durability compared to silicate glasses, allowing for increased degradation rates and potentially accelerated benefits in the healing process. Recently, the sol-gel process was used to fabricate borate glasses with high specific surface areas (SSAs) leading to rapid dissolution and high reactivity when compared to their melt-quench derived equivalents. In this study, silver doped sol-gel derived borate glasses (AgBGs) were developed to impart anti-bacterial properties, thus potentially offering treatment for chronic and infected wounds. In order to optimize glass composition, the sol-gel processing route was adapted to generate two different AgBG compositional ranges; (46)B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(27)CaO-(24-X)Na〈sub〉2〈/sub〉O-(3)P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉-(X)Ag〈sub〉2〈/sub〉O where X = 0, 0.15, 0.5 and 1 (mol%) and (60)B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(36)CaO-(4-X)P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉-(X)Ag〈sub〉2〈/sub〉O where X = 0, 0.3, 0.5 and 1 (mol%). It was demonstrated that the latter, sodium-free formulation resulted in enhanced silver incorporation with high SSA (237–300 m〈sup〉2〈/sup〉/g) and small pore width (31–44 Å) values. XRD and ATR-FTIR were used to verify the amorphous nature of the glasses and the presence of BO〈sub〉3〈/sub〉 and BO〈sub〉4〈/sub〉 units as the glass network former, respectively. Extent of silver ion release from the dissolution of AgBG in deionized water verified its dependency on the processing route and glass composition. Additionally, the anti-bacterial activity of AgBGs against 〈em〉Escherichia coli〈/em〉 and 〈em〉Staphylococcus aureus〈/em〉 was correlated with silver ion release. To the best of our knowledge, this is the first report demonstrating the potential use of anti-bacterial sol-gel derived AgBGs for potential wound healing applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): F. Ahmadi, A. Asgari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sm〈sup〉3+〈/sup〉-doped zinc magnesium sulfophosphate glasses were synthesized by conventional melt-quench technique. FTIR spectra were recorded to investigate the structural properties of the glasses. Differential thermal analysis (DTA) was confirmed the thermal stability of studied glass samples. UV–Vis-NIR absorption spectroscopy was obtained and J-O analysis was determined to derive the spectroscopic properties of Sm〈sup〉3+〈/sup〉 doped zinc magnesium sulfophosphate glasses. Spontaneous radiative transition probabilities (A), radiative lifetimes (〈em〉τ〈/em〉〈sub〉〈em〉R〈/em〉〈/sub〉), branching ratios (〈em〉β〈/em〉) for the excited 〈sup〉4〈/sup〉G〈sub〉5/2〈/sub〉 transition level were calculated and discussed. Thirteen absorption peaks were exhibited in the UV–Vis-NIR spectra. Emission spectra exhibited four significant peaks located at 561, 596, 643 and 703 nm which are assigned to the 〈sup〉4〈/sup〉G〈sub〉5/2〈/sub〉→〈sup〉6〈/sup〉H〈sub〉5/2〈/sub〉, 〈sup〉4〈/sup〉G〈sub〉5/2〈/sub〉→〈sup〉6〈/sup〉H〈sub〉7/2〈/sub〉, 〈sup〉4〈/sup〉G〈sub〉5/2〈/sub〉→〈sup〉6〈/sup〉H〈sub〉9/2〈/sub〉 and 〈sup〉4〈/sup〉G〈sub〉5/2〈/sub〉→〈sup〉6〈/sup〉H〈sub〉11/2〈/sub〉 transitions, respectively and the intensities of all bands were quenched by addition of ZnSO〈sub〉4〈/sub〉 ions contents. The results revealed that the PMS-ZS10 glass matrix has the higher values of branching ratios and emission cross-sections for 〈sup〉4〈/sup〉G〈sub〉5/2〈/sub〉→〈sup〉6〈/sup〉H〈sub〉7/2〈/sub〉 transition. It is observed that the Sm〈sup〉3+〈/sup〉-doped zinc magnesium sulfophosphate glass can be promise candidate for lasers in the visible range.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 505〈/p〉 〈p〉Author(s): Rafał Babilas, Anna Bajorek, Laszlo Temleitner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure of amorphous and nanocrystalline Mg〈sub〉65〈/sub〉Cu〈sub〉20〈/sub〉Y〈sub〉10〈/sub〉Zn〈sub〉5〈/sub〉 alloy in as-quenched and post-annealed state was examined using neutron diffraction (ND), Reverse Monte Carlo modeling (RMC) and high-resolution transmission electron microscopy (HRTEM). The surface characteristic of Mg-based glass was investigated by X-ray photoelectron spectroscopy (XPS) method. The corrosion activity of alloy in glassy and nanocrystalline state was determined by electrochemical polarization measurements conducted in 3.5% NaCl solution. It was found that the structure of the melt-spun glass is homogeneous, but some medium-range order (MRO) regions as small as 1–2 nm were observed. The RMC analysis of ND data was used for local atomic structure and coordination numbers of the Mg〈sub〉65〈/sub〉Cu〈sub〉20〈/sub〉Y〈sub〉10〈/sub〉Zn〈sub〉5〈/sub〉 alloy in as-quenched state. The three-dimensional model representing a simulation box with atomic arrangements was also proposed. An average coordination number for Mg-Mg and Mg-Cu atoms is 8.1 and 2.5, adequately. The formation of nanocrystalline structure after annealing was confirmed by X-ray diffraction (XRD) and HRTEM observations. The TEM and HRTEM techniques allowed to observe regions containing very small particles in the amorphous matrix with size of 4–10 nm. The selected area electron diffraction (SAED) patterns allowed to identified hexagonal Mg and orthorhombic Mg〈sub〉2〈/sub〉Cu phases. XPS results indicated the co-existence of MgO and Mg(OH)〈sub〉2〈/sub〉 on the surface film formed on glassy ribbon in as-quenched state. The electrochemical polarization measurements revealed that the glassy ribbon exhibited lower corrosion current density than nanocrystalline sample.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volumes 503–504〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Xia Guo, Wenfeng Li, Heping Wang, Yan-Ying Fan, Huifang Wang, Xianghua Gao, Baolong Niu, Xuechen Gong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the study, amorphous calcium phosphate (ACP) nanoparticles were prepared by the coprecipitation method to optimize release profile of curcumin (Cur) and avoid burst releases, which were used to overcome the weakness of Cur, such as poor chemical stability and bioavailability. To find the best preparation condition, the influence of reaction concentration, temperature, time and pH on crystal phase of the samples was investigated by XRD and FTIR. The results showed that amorphous calcium phosphate (ACP) was obtained, when pH value and the concentration of PO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 were 8 and 0.024 mM, prepared at 30 °C for 10 min. In vitro drug release assay, ACP nanoparticles showed high loading capacity of Cur and favorable pH-responsive drug release properties. Furthermore, the Cur-load ACP nanoparticles showed an excellent ability to scavenge free radical and damage A549 cells, resulting in a high antioxidant properties and low cell viability. Therefore, the as-prepared nanoparticles have promising applications in the food and biomedical fields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022309318304952-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Ehsan Bahadori Yekta, Amir Hossein Taghvaei, Shahriyar Sharafi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the structural, thermal and magnetic characteristics of Fe〈sub〉75-x〈/sub〉Ta〈sub〉5〈/sub〉Si〈sub〉10〈/sub〉C〈sub〉10+x〈/sub〉 (x = 0, 5, 10) powders processed by mechanical alloying (MA) were investigated. The X-ray diffraction (XRD) indicated that by increasing the level of carbon, the structural refinement and lattice strain of the nanocrystalline Fe-based solid solution formed in the early stages of milling are enhanced. Furthermore, quantitative XRD analyses demonstrated that the glass forming ability (GFA) is remarkably improved by increasing the amount of carbon, where the percentage of amorphous phase increases from 56% for x = 0 to 98% for x = 10 after 120 h of milling. In addition, thermodynamic calculations, based on the extended Miedema's model, showed that the driving force for the glass formation increases with the concentration of carbon. Also, thermal analyses demonstrated that both the glass transition (〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉) and the onset of the crystallization (〈em〉T〈/em〉〈sub〉〈em〉x〈/em〉〈/sub〉) temperatures increase with the content of carbon, suggesting an enhanced thermal stability of the glassy phase. Additionally, the extension of the supercooled liquid region for the alloys with x = 5 and 10 reached a large value of 75 and 78 K, respectively, manifesting a high thermal stability of their supercooled liquid. Magnetic measurements showed that the soft magnetic behavior of the powders milled for 120 h is improved by increasing the level of carbon in terms of a decrease in coercivity (〈em〉H〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉) from 3.7 kA/m for x = 0 to 2.1 kA/m for x = 10. The evolution of the magnetic properties with annealing temperature reflected that the alloy with x = 10 displays a minimum 〈em〉H〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 of 1.2 kA/m after annealing at 673 K.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Miroslava Vernerová, Lubomír Němec, Jaroslav Kloužek, Miroslava Hujová〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heterogeneous bubble nucleation during the production of commercial glasses is one of the negative factors affecting their technology and technical properties. In order to eliminate these bubbles, we conducted extensive research of bubble nucleation in soda-lime-silica glass melts at increasing temperatures and variable redox states of glass. Evolved gas analysis (EGA) coupled with gas chromatography and mass spectrometry were used to identify and evaluate crucial chemical reactions during the melting. The reactions were indicated also by the bubble compositions estimated from bubble contraction during the temperature drop. The fining action of sulfates in the reducing conditions was observed at temperatures between 1200 and 1300 °C using high temperature monitoring. This was confirmed by the relatively high average values of the bubble growth rates. In addition, extensive nucleation of bubbles took place at relatively low temperatures. The temperature region of nucleation was determined by monitoring bubble nucleation on the Pt wire immersed in the melt at increasing temperatures. The nucleation of the bubbles in variously reduced glasses has been observed at temperatures even lower than 1300 °C which further decreased with the increasing 〈em〉C/SO〈/em〉〈sub〉〈em〉4〈/em〉〈/sub〉〈sup〉〈em〉2−〈/em〉〈/sup〉 ratio. Next, we tried to clarify whether the process of bubble nucleation at a low redox state of glass was caused by supersaturation of the glass melt by either physically dissolved or chemically bound gases. We suppose that the nucleation of bubbles SO〈sub〉2〈/sub〉 around 1300 °C can be attributed to the reaction between the sulfate remaining in melts and sulfides which have been formed by reduction reactions.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Hélène Celerier, Jenny Jouin, Nicolas Tessier-Doyen, Sylvie Rossignol〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different formulations of geopolymers were synthesized in acidic media (phosphoric acid) starting from three different raw metakaolin materials to identify compositions of interest. Four different property groups were highlighted based on the most favorable thermal and water resistance properties (while maintaining acceptable mechanical properties). The groups were related to the chemical composition, setting time and setting temperature of the synthesized geopolymers. Indeed, mechanical strength was determined by chemical composition, such as the aluminum content and the amount of water in each sample. The results showed that the sample with Si/Al ≥ 1 and Al/〈em〉P〈/em〉 = 1 exhibited compressive stress to rupture values ranging between 66 and 120 MPa and was thermal resistant. Water resistance with a mechanical strength of 50 MPa was obtained for the samples with Al/〈em〉P〈/em〉 = 1 or 4 and Si/Al ≤ 1. This work highlights the possibility of selecting a specific property associated with the mechanical performance for an acidic geopolymer.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Weihui Lin, Chao Zhang, Jia Fu, Hao Xin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dynamic mechanical behaviors of the calcium silicate hydrate (C-S-H) under shock compression loading in layered direction have been investigated by molecular dynamics (MD) simulations. The various piston velocities ranging from 0.2 to 3.0 km/s used to describe the propagation of stress waves have been employed in our MD simulations. The shock Hugoniot curve and the distribution of particle velocity are obtained. It is found that the Hugoniot elastic limit is 7.5 GPa, and the impact may induce elastic response, elastic-plastic response and shock regime. Our results reveal that only a continuous elastic wave exists when the particle velocity is below 0.5 km/s, while a new wave is generated when the particle velocity is at 0.5 km/s. With further increasing the particle velocity, a two-wave structure is generated. After the particle velocity is larger than 2.0 km/s, the shock wave is dominant. These findings provide important atomic insights for understanding the dynamic mechanical behaviors of C-S-H.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022309318305246-ga1.jpg" width="384" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): A. Geslain, J.-P. Groby, V. Romero-García, F. Cervera, J. Sánchez-Dehesa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A multiobjective optimization procedure is employed to retrieve the viscoelatic parameters of silica aerogel clamped plates. This retrieval method preserves the aerogel sample integrity and, in contrast to the existing ones, relies on the minimization of two different cost functions. The first one, namely 〈em〉J〈/em〉〈sub〉1〈/sub〉, is related to the reflective properties of clamped plates backed by a rigid cavity, while the second one, namely 〈em〉J〈/em〉〈sub〉2〈/sub〉, concerns both the reflectance and transmittance spectra measured in transmission configuration. The recovered parameters are in agreement with previously reported values in the literature. In addition, they are also supported by designing structures for perfect absorption (100% of absorption), which has been validated experimentally. Aerogel plates can be therefore used as innovative building units of artificial structures for the broadband absorption of sound.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Max Fraenkl, Bozena Frumarova, Veronika Podzemna, Stanislav Slang, Ludvik Benes, Milan Vlcek, Tomas Wagner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The presented study shows how the incorporation of silver changes the structure and physical properties of chalcogenide glass (GeS〈sub〉2〈/sub〉)〈sub〉50〈/sub〉(Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉)〈sub〉50〈/sub〉. Nine samples with silver content (0–25 at. %) were studied to give a detailed picture. The structure and its changes were analyzed by Raman spectroscopy. The medium range order of the (GeS〈sub〉2〈/sub〉)〈sub〉50〈/sub〉(Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉)〈sub〉50〈/sub〉 glass was identified. The structural motif of interconnected SbS〈sub〉3/2〈/sub〉 pyramids is the doorway for the silver incorporation in the (GeS〈sub〉2〈/sub〉)〈sub〉50〈/sub〉(Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉)〈sub〉50〈/sub〉 glass. The material hardness is significantly increased by up to 26% due to silver addition. The ability of silver to fill cavities in a glass is responsible for the observed hardness increase. Electronic properties and silver ion mobility were examined by impedance spectroscopy and radioactive tracer diffusion. The purpose of the presented study is to give an instructive description of how silver change the structure of the studied chalcogenide glass and give a complex feeling of how the silver changes its physical properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): A.S. Makarov, G.V. Afonin, Yu.P. Mitrofanov, R.A. Konchakov, N.P. Kobelev, J.C. Qiao, V.A. Khonik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Precise measurements of shear modulus changes and heat effects occurring upon heating of bulk glassy 〈em〉Pd〈/em〉〈sub〉40〈/sub〉〈em〉Ni〈/em〉〈sub〉40〈/sub〉〈em〉P〈/em〉〈sub〉20〈/sub〉 from room temperature into the supercooled liquid region are performed. It is found the absorbed heat increases linearly with the shear modulus measured near room temperature, in excellent agreement with the prediction of the Interstitialcy theory.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Yue Kang, Chao Liu, Yuzhu Zhang, Hongwei Xing, Maofa Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Slag beads with different amorphous phase contents can be prepared by gas quenching of blast furnace slag (BFS). The amorphous phase content can affect the activity of these slag beads, with higher amorphous phase contents leading to higher activity. In this study, thermodynamic simulations with FactSage 7.1 and differential scanning calorimetry were used to investigate the crystallization behavior of BFS during continuous cooling. The influence of different cooling rates and basicities on the crystallization behavior of BFS was studied, and the activation energy for crystallization was calculated by the Kissinger and Ozawa methods. The results showed that the precipitation of crystals could be prevented at high cooling rates and low BFS basicity. Accordingly, no precipitation of BFS crystals was observed when basicity was less than 0.91 and the cooling rate was above 50 °C/min. In addition, the activation energy for crystallization of BFS decreased with increasing basicity〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Jianbiao Wang, Haihui Ruan, Xu Wang, Jianquan Wan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present work investigates the validity of using the frequency and decay rate of free-free beam vibration, which are measured by the impulse excitation technique (IET), to characterize the viscoelastic properties of glass in the temperature range of glass transition. Based first on the classical Burgers model, we show that the temperature-dependent flow viscosity of borosilicate glass, calculated from the measured frequency and amplitude decay rate of the flexural vibration, agrees very well with the existing data. While for chalcogenide glass, the same calculation approach does not render the similar agreement, and the reason probably lies in non-exponential effects. To comprehend the IET data in the temperature range of glass transition, we propose a simplified theoretical framework for describing the transition from the solid-like to liquid-like viscoelastic behavior and discuss the cause of difference of the rheology behaviors of these two types of glass based on the formulation of non-exponential relaxation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Zheming Zheng, John C. Mauro, Douglas C. Allan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have developed a numerical model based on finite element analysis (FEA) with a viscoelastic material model coupling stress relaxation and structural relaxation, using the Mauro-Allan-Potuzak (MAP) non-equilibrium viscosity equation as the shift function. A modeling study of the delayed elasticity behavior in glass under different equilibrium viscosity and non-equilibrium viscosity conditions is conducted. The delayed elastic response is found to be well described by a stretched exponential function with three parameters: the maximum delayed elasticity response, the retardation time of delayed elasticity response, and the stretching exponent of delayed elasticity response. The delayed elasticity magnitude is seen to increase with lower values of the stretching exponent 〈em〉b〈/em〉〈sub〉〈em〉stress〈/em〉〈/sub〉. At equilibrium viscosity, the retardation time shows a linear relationship with the stress relaxation time. However, when the temperature drops sharply in the non-equilibrium viscosity cases, the delayed elastic response may be frozen resulting in a lower magnitude for the delayed elasticity and the retardation time is not linear any more with the stress relaxation time. The delayed elasticity stretching exponent is seen to vary slightly at different relaxation times and normalized delayed elasticity response can roughly be collapsed into a single master curve. The impact of liquid fragility is also studied.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Oriane Baulin, Damien Fabrègue, Hidemi Kato, Takeshi Wada, Sandra Balvay, Daniel J. Hartmann, Jean-Marc Pelletier〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biomaterials are attracting an ever-increasing research interest. As part of this overall effort, we report herein the fabrication and characteristics of Zr-based ribbon samples with three different compositions: Zr〈sub〉56〈/sub〉Co〈sub〉28〈/sub〉Ga〈sub〉16〈/sub〉, Zr〈sub〉56〈/sub〉Co〈sub〉28〈/sub〉Ga〈sub〉14〈/sub〉Si〈sub〉2〈/sub〉, and Zr〈sub〉56〈/sub〉Co〈sub〉28〈/sub〉Ga〈sub〉14〈/sub〉Sn〈sub〉2〈/sub〉. The supercooled-liquid region Δ〈em〉T〈/em〉 = 〈em〉T〈/em〉〈sub〉x〈/sub〉 − 〈em〉T〈/em〉〈sub〉g〈/sub〉 of these materials is 16, 18, and 29 K, respectively, where 〈em〉T〈/em〉〈sub〉x〈/sub〉 is the temperature of the onset of crystallization and 〈em〉T〈/em〉〈sub〉g〈/sub〉 is the glass-transition temperature. The samples are thermally characterized by using differential scanning calorimetry and by determining the activation energy. The corrosion resistance is determined by immersing the materials for up to 20 days in a simulated body fluid, and the cytotoxicity is measured from the proliferation of osteoblast-like cells on the samples. Finally, the mechanical properties are investigated by nanoindentation. The Young's modulus is 112 GPa. These results all highlight the suitability of this metallic glass for biomedical applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): M.S. Pathak, N.O. Gopal, N. Singh, M. Mohapatra, J.L. Rao, Jung-Kul Lee, Vijay Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Iron doped lithium metasilicate sample was synthesized using a combustion technique and characterized by XRD (X ray diffraction), SEM (scanning electron microscopy), FTIR (Fourier transform infrared spectroscopy), optical, and EPR (electron paramagnetic resonance) analyses. The phase purity of the combustion synthesized products was confirmed by XRD analysis. SEM data suggested the formation of a porous compound by virtue of the entrapment of the gases that evolved during the sample synthesis. FTIR data confirmed the formation of Si〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bonds in the system. Optical data confirmed the existence of both divalent and trivalent iron in the system. Characteristic absorption bands in the region 215–270 nm and 535–620 nm were observed due to the presence of Fe〈sup〉3+〈/sup〉 in Oh and Td geometry respectively. On the other hand, the presence of bands at 967 and 1442 nm suggested the stabilisation of Fe〈sup〉2+〈/sup〉 also in both Oh and Td geometries, respectively. The divalent iron being a non-Kramer ion, could not be observed by EPR. However, strong temperature-dependent EPR signals were observed in the sample owing to Fe〈sup〉3+〈/sup〉. By analyzing the EPR data, super-paramagnetic type of behaviour was observed in the system. Furthermore, the relaxation times along with other EPR spectroscopic parameters were estimated for the system.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Leibo Deng, Xuefeng Zhang, Mingxing Zhang, Xiaolin Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bayan Obo tailings (BOTs), fly ash (FAS), and stainless-steel slag (SSS) are industrial wastes that require reasonable, clean, and effective utilization for environment protection. The paper focuses on the structure and properties of glass-ceramics that were prepared by melting BOT, FAS, and SSS raw materials. The effect of CaF〈sub〉2〈/sub〉 on the viscosity, structure, and performance of CaO-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-MgO-SiO〈sub〉2〈/sub〉 (CAMS) slag glass-ceramics is determined by viscometer, differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and physicochemical properties measurements. The results show that moderate amounts of CaF〈sub〉2〈/sub〉 facilitates depolymerization of the silicate networks, which leads to a decrease in the melting temperature, viscosity and viscous activation energy of glass. However, the content of more than 3% CaF〈sub〉2〈/sub〉 results in a dramatic decreases in the chemical stability of the glass-ceramics because of the transformations of the main crystalline phase from diopside to anorthite, which is accompanied by fluorite precipitation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Preethi Balasubramanian, Antonio J. Salinas, Sandra Sanchez-Salcedo, Rainer Detsch, Maria Vallet-Regi, Aldo R. Boccaccini〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Certain biomaterials are capable of inducing the secretion of Vascular Endothelial Growth Factor (VEGF) from cells exposed to their biochemical influence, which plays a vital role in stimulating angiogenesis. Looking for this capacity, in this study three porous glasses were synthesized and characterized. Glass compositions (in mol-%) were: 60SiO〈sub〉2〈/sub〉–(36-2x)CaO–4P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉–xCuO–xSrO with x = 0, 1 or 2.5, respectively, for B60, CuSr-1 or CuSr-2.5 glasses. Cu〈sup〉2+〈/sup〉 and Sr〈sup〉2+〈/sup〉 ions were added because of the reported biological capabilities of Cu〈sup〉2+〈/sup〉 as angiogenic stimulator and Sr〈sup〉2+〈/sup〉 as osteogenic stimulator. The objective of this study was to determine the concentration of the glass particles that, being out of the cytotoxic range, could increase VEGF secretion. The viability of cultivated bone marrow stromal cells (ST-2) was assessed. The samples were examined with light microscopy (LM) after the histochemical staining for haematoxylin and eosin (HE). The biological activity of glasses was evaluated in terms of the influence of the Cu〈sup〉2+〈/sup〉 and Sr〈sup〉2+〈/sup〉 ions on the cells. The dissolution products of CuSr-1 and CuSr-2.5 produced the highest secretion of VEGF from ST-2 cells after 48 h of incubation. The combination of Cu〈sup〉2+〈/sup〉 and Sr〈sup〉2+〈/sup〉 lays the foundation for engineering a bioactive glass than can lead to vascularized, functional bone tissue when used in bone regeneration applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Alexander S. Abyzov, Vladimir M. Fokin, Edgar D. Zanotto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We employed the Classical Nucleation Theory using a characteristic value of the pre-exponential constant and an average (temperature dependent) interfacial energy and derived an expression to estimate the maximum nucleation rates, 〈em〉I〈/em〉〈sub〉max〈/sub〉, as a function of the reduced glass transition temperatures, 〈em〉T〈/em〉〈sub〉〈em〉gr〈/em〉〈/sub〉 ≡ 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉/〈em〉T〈/em〉〈sub〉〈em〉m〈/em〉〈/sub〉 (〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 is the laboratory glass transition temperature and 〈em〉T〈/em〉〈sub〉〈em〉m〈/em〉〈/sub〉 is the melting point or 〈em〉liquidus〈/em〉 temperature). The theoretical predictions were surprisingly good for 51 out of 54 silicate glass-formers tested and describe well the experimental trend that 〈em〉I〈/em〉〈sub〉max〈/sub〉 strongly decreases with increasing 〈em〉T〈/em〉〈sub〉〈em〉gr〈/em〉〈/sub〉. This trend, in turn, explains the well-known fact that only silicate glasses having a relatively low 〈em〉T〈/em〉〈sub〉〈em〉gr〈/em〉〈/sub〉, 〈em〉T〈/em〉〈sub〉〈em〉gr〈/em〉〈/sub〉 〈 0.6, show internal homogeneous nucleation in laboratory time/sample-size scales.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Ziyad Chaker, Guido Ori, Christine Tugène, Sébastien Le Roux, Mauro Boero, Carlo Massobrio, Evelyne Martin, Assil Bouzid〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent first-principles molecular dynamics simulations (FPMD) results on two chalcogenide glasses (glassy GeS〈sub〉4〈/sub〉 and GeSe〈sub〉4〈/sub〉) are revisited by accounting explicitly for van der Waals (vdW) dispersion forces. This effort is motivated by the observation that such contributions were found to be important in the case of glassy GeTe〈sub〉4〈/sub〉 while they were negligible for another disordered chalcogenide system, liquid GeSe〈sub〉2〈/sub〉. With the present results, we provide additional evidence intended to establish under which conditions and for which systems the consideration of dispersion forces plays a role in determining the atomic structure. For these purposes we employ two different dispersion schemes used in conjunction with the BLYP (Becke, Lee, Yang and Parr) exchange-correlation functional. The first is the DFT-D2 vdW correction introduced by Grimme et al. (Grimme (2006) [1]) while the second is the vdW〈sub〉〈em〉W〈/em〉〈/sub〉 approach based on the Wannier functions analysis (Silvestrelli, 2008 [2]). The atomic structures obtained agree well with the ones obtained by Bouzid et al. [3] without considering dispersion forces. Due to the vdW interactions, glassy GeSe〈sub〉4〈/sub〉 features a higher number of Ge fourfold coordinated. The two vdW approaches also agree to a large extent, exceptions occurring for some moderate differences in the intensity of the peaks in the Ge-Ge pair correlation function.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Fabien Pacaud, Mathieu Salanne, Thibault Charpentier, Laurent Cormier, Jean-Marc Delaye〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The properties of Na〈sub〉2〈/sub〉O-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-SiO〈sub〉2〈/sub〉+La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 glasses (NBS_La) are not well understood. In particular the influence of the lanthanides on the polymerized network structure and organization are not well known. In this work, we use a Polarizable Ion Model (PIM) that was fitted on electronic structure calculations to simulate a series of NBS_La glasses using molecular dynamics. The simulations account well for the main structural characteristics of NBS_La glasses such as the structure factors and the ionic local environments despite minor discrepancies with experiments about the Si-O distance and the B coordination. In particular, we examine the impact of La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 addition to Na〈sub〉2〈/sub〉O-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-SiO〈sub〉2〈/sub〉 glasses in term of structural changes and in the Na migration paths which become more homogeneous.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Dao Zhang, Wen Feng, Xiaoyan Wang, Sen Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Size constrains of traditional rapid solidification processes for fabrication of Mg-Zn-Ca bulk metallic glasses have limited their biomedical applications as implants. In this work, large-sized Mg〈sub〉65〈/sub〉Zn〈sub〉30〈/sub〉Ca〈sub〉5〈/sub〉 amorphous coating was fabricated by laser remelting. The microstructure characterization and phase analysis indicated that the laser remelted coating was mainly composed of amorphous with a small amount of metastable crystalline Mg〈sub〉51〈/sub〉Zn〈sub〉20〈/sub〉. The thermal stability and crystallization behavior of the produced Mg〈sub〉65〈/sub〉Zn〈sub〉30〈/sub〉Ca〈sub〉5〈/sub〉 coating were invested by differential scanning calorimetry. Results of potentiodynamic polarization test showed that the amorphous coating exhibited excellent corrosion resistance properties, which in close proximity to the Mg〈sub〉65〈/sub〉Zn〈sub〉30〈/sub〉Ca〈sub〉5〈/sub〉 glassy ribbon. All these results suggested that the Mg〈sub〉65〈/sub〉Zn〈sub〉30〈/sub〉Ca〈sub〉5〈/sub〉 amorphous coating could expand the potential application of Mg-Zn-Ca metallic glasses in the field of biomedicine.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): H. Chen, Y.X. Song, T.H. Zhang, M. Wu, Y. Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The annealing effect below glass transition temperature (〈em〉T〈/em〉〈sub〉g〈/sub〉) on nanoindentation hardness and shear transformation zone (STZ) volume was studied in a Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Nb metallic glassy thin film. The indentation size effect (ISE) and loading rate effect on hardness were systematically investigated. It was found that ISE was less pronounced and strain rate sensitivity (SRS) was higher in the sample suffered longer annealing time. As annealing time reached a critical value, hardness value, ISE and SRS changed quite limited which could be due to full structure relaxation in samples. The hardness spatial distribution was more scattered with increasing annealing time, indicating a more pronounced mechanical heterogeneity at microscale. Based on SRS values and cumulative probability distribution of hardness, STZ volumes were estimated upon two distinct methods, respectively. A tight correlation between STZ volume and structure state was revealed. As increasing annealing time, STZ volume was continuously decreased and approached down to a stable value.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): M. Kotrlová, P. Zeman, Š. Zuzjaková, M. Zítek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Amorphous Zr〈sub〉54〈/sub〉Cu〈sub〉46〈/sub〉 and Zr〈sub〉27〈/sub〉Hf〈sub〉27〈/sub〉Cu〈sub〉46〈/sub〉 thin-film metallic glasses were prepared by non-reactive magnetron co-sputtering of Zr, Hf and Cu in pure argon. Several as-deposited Zr〈sub〉54〈/sub〉Cu〈sub〉46〈/sub〉 films were post-annealed in high vacuum to create a crystalline thin-film alloy of the identical composition. The non-isothermal crystallization behavior of the amorphous Zr〈sub〉54〈/sub〉Cu〈sub〉46〈/sub〉 and Zr〈sub〉27〈/sub〉Hf〈sub〉27〈/sub〉Cu〈sub〉46〈/sub〉 films and the effect of a substitution of Hf for Zr on the crystallization process were studied by differential scanning calorimetry. The activation energy of the crystallization was obtained by the Kissinger–Akahira–Sunose method. The results show that the activation energy of the Zr〈sub〉27〈/sub〉Hf〈sub〉27〈/sub〉Cu〈sub〉46〈/sub〉 film was higher for all conversion fractions, which indicates that the substitution of Hf for Zr enhances the thermal stability of the glassy state. Considerable attention was also paid to the isothermal oxidation behavior of the amorphous and crystalline Zr〈sub〉54〈/sub〉Cu〈sub〉46〈/sub〉, and amorphous Zr〈sub〉27〈/sub〉Hf〈sub〉27〈/sub〉Cu〈sub〉46〈/sub〉 films investigated by thermogravimetric analysis. It was shown that all oxidation curves in the temperature range from 400 to 575 °C obeyed the parabolic law. The activation energy of the oxidation process determined by the Arrhenius equation for the oxidation rate constants was found to be the highest for the Zr〈sub〉27〈/sub〉Hf〈sub〉27〈/sub〉Cu〈sub〉46〈/sub〉 film, which indicates that its surface oxide layer is a more effective barrier against the diffusion of species.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Milica M. Vasić, Tomáš Žák, Naděžda Pizúrová, Pavla Roupcová, Dušan M. Minić, Dragica M. Minić〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The amorphous Co〈sub〉70〈/sub〉Fe〈sub〉5〈/sub〉Si〈sub〉10〈/sub〉B〈sub〉15〈/sub〉 alloy was studied in terms of thermal and corrosion resistance as well as thermally induced structural transformations, using several structural and thermal analysis techniques and electrochemical measurements. It was shown that the alloy is thermally stable up to around 510 °C. Anodic polarization curves of the as-prepared alloy revealed its high corrosion resistance in 0.5 M NaCl, HCl and NaOH solutions. Multistep structural stabilization through the crystallization is manifested as two well defined DSC peaks corresponding to formation of fcc Co, hcp Co, Co〈sub〉23〈/sub〉B〈sub〉6〈/sub〉, and Co〈sub〉2〈/sub〉Si phases, whose microstructural parameters were studied after thermal treatment at different temperatures in the range 25–800 °C. TEM and EDX analyses suggested the presence of minor Co-Si phases as well in the crystallized alloy and deformation twinning in the Co〈sub〉23〈/sub〉B〈sub〉6〈/sub〉 grains. The microstructural transformations exhibited significant influence on the magnetic moment of the alloy. Kinetics of non-isothermal crystallization was studied on the bases of isoconversional principle. Determination of kinetic triplets of individual crystallization steps, based on deconvolution of the complex DSC peaks applying Fraser-Suzuki function, enabled assessment of thermal stability of the alloy and kinetic predictions at different temperatures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): N.B. Pimentel, V.R. Mastelaro, J.-C. M'Peko, S.W. Martin, S.S. Rojas, J.E. De Souza〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Glasses in the ternary xLi〈sub〉2〈/sub〉O + (33-x)CaO + 67B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 tetraborate system, with x = 0, 5, 10, 15, 20, 25, 30 and 33 mol%, were prepared by melting and casting. The glass structure, and thermal, and electrical response of highly transparent and homogeneous glasses were evaluated by X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Fourier Transform Infrared Spectroscopy (FTIR) and Impedance Spectroscopy (IS). The glass transition temperature (T〈sub〉g〈/sub〉) decreases as CaO is substituted by Li〈sub〉2〈/sub〉O (increasing x), while the thermal stability against crystallization to the supercooled liquid in the region T〈sub〉g〈/sub〉 〈 T 〈 T〈sub〉l〈/sub〉, where T〈sub〉l〈/sub〉 is the liquidus temperature, increases up to x = 20, according to ΔT ≡ (T〈sub〉oc〈/sub〉 - T〈sub〉g〈/sub〉), where T〈sub〉oc〈/sub〉 is the onset temperature of the first exotherm crystallization, and also considering the Hubrÿ's (K〈sub〉H〈/sub〉), and Weinberg's (K〈sub〉W〈/sub〉) thermal parameters. The short range order (SRO) structural change in this glass series is governed by the isomerization reaction BØ〈sub〉2〈/sub〉O〈sup〉−〈/sup〉 ⇔ BØ〈sub〉4〈/sub〉〈sup〉−〈/sup〉, also designated as B〈sup〉2〈/sup〉 ⇔ B〈sup〉4〈/sup〉, where the superscript defines the number of bridging oxygens (BOs) on the SRO structural units. Li〈sub〉2〈/sub〉O substituting CaO in this tetraborate glass compositional series favors the formation of tetrahedral boron, B〈sup〉4〈/sup〉 SRO units, isomerization reaction for compositions up to 10 mol%. For glasses at higher lithium oxide contents, the reaction in the opposite direction is favored towards the formation of the metaborate B〈sup〉2〈/sup〉 SRO units. A dramatic increase in the ionic conductivity at 300 °C of more than 10 orders of magnitude was observed across this same compositional series. This dramatic increase is related to the higher mobility of the Li〈sup〉+〈/sup〉 ions, which has a smaller ionic radius, 0.59 Å (four-fold coordination) and a single ionic charge compared the significantly larger, 1.00 Å (six-fold coordination) and divalently charged Ca〈sup〉2+〈/sup〉 ions in the glassy structure arrangement.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Ang Qiao, Pengpeng Wang, Haizheng Tao, Yuanzheng Yue〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigate the sub-〈em〉T〈/em〉〈sub〉g〈/sub〉 relaxation in both the mechanically milled and the quenched As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 glasses by a differential scanning calorimeter (DSC). The results show that the sub-〈em〉T〈/em〉〈sub〉g〈/sub〉 enthalpy relaxation pattern of the milled As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 glass is similar to that of the quenched glass, but the fictive temperature (〈em〉T〈/em〉〈sub〉f〈/sub〉) of the former is higher than that of the latter. By performing sub-〈em〉T〈/em〉〈sub〉g〈/sub〉 annealing, we find that the quenched As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 glass exhibits the Johari-Goldstein (JG) relaxation, whereas the milled glass shows the relaxation behavior with the activation energy of ~32〈em〉RT〈/em〉〈sub〉g〈/sub〉 that deviates from the average value of 24〈em〉RT〈/em〉〈sub〉g〈/sub〉 for the JG relaxation. An endotherm occurs prior to the sub-〈em〉T〈/em〉〈sub〉g〈/sub〉 relaxation peak when the milled glass undergoes sufficient sub-〈em〉T〈/em〉〈sub〉g〈/sub〉 annealing (temperature and time). The occurrence of the endothermic pre-peak and the higher activation energy of the milled glass imply its higher structural heterogeneity compared to the quenched glass. The Raman and X-ray photoelectron spectra indicate the existence of the As〈sub〉4〈/sub〉S〈sub〉4〈/sub〉 clusters and -S-S- chains in both the milled and the quenched glasses, confirming their structural heterogeneity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): I.V. Reduto, V.P. Kaasik, A.A. Lipovskii, D.K. Tagantsev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It has been shown that the additional annealing of thermally poled silicate glasses at temperatures exceeding the glass poling temperature and close to, but below, the glass transition temperature leads to an essential decrease of the volume of polarized regions and, as the result, to an increase in the height of the surface relief structures formed by poling with profiled relief anodic electrode. Thermodynamic and rheological explanations of the found volume decrease are given.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Nicolas Piret, Ronny Santoro, Loïck Dogot, Bastien Barthélemy, Eugénie Peyroux, Joris Proost〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉During etching of a multicomponent glass in concentrated hydrofluoric acid (HF) solutions, a crust can gradually appear on the glass surface, depending on the chemical etching parameters. This crust deposition is the result of the precipitation of hexafluorosilicate anions released by the glass dissolution reaction, with cations coming either from the etching solution or from the glass (like Na〈sup〉+〈/sup〉, K〈sup〉+〈/sup〉 or Ca〈sup〉2+〈/sup〉). To understand the impact of this crust on the overall kinetics of both the etching and frosting process, we have studied the dissolution of four types of commercial glass substrates in etching solutions containing various concentrations of HF. The kinetics of the frosting process was investigated by two independent methods: on the one hand the chemical analysis by ICP-OES of the amount of Si dissolved from the glass as a function of time, and on the other hand the measurement of the glass weight loss with time. These two methods showed that the glass etching rate decreases with time as a result of crust formation which gradually becomes more protective. Both methods also indicated that increasing the amount of HF in the etching solution increases the etching rate in a non-linear way, and that the etching rate increases with the alumina content of the glass. A separate chemical analysis of the amount of Si present in the crust also revealed that the amount of HF in the etching solution has an impact on the amount of crust deposited on the glass surface. Finally, we have been able to rationalize all these kinetic data based on a semi-empirical quantitative etching and frosting model, allowing to extract a characteristic dissolution and precipitation constant (〈em〉K〈/em〉〈sub〉diss〈/sub〉 and 〈em〉K〈/em〉〈sub〉dep〈/sub〉), respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Pritam Khan, Yinsheng Xu, William Leon, K.V. Adarsh, Dmitri Vezenov, Ivan Biaggio, Himanshu Jain〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chalcogenide glass – silver heterostructures are candidates for photoresist and diffractive optical applications. To optimize their processing, we report the kinetics of Ag photo-dissolution in As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 matrix using in-situ optical transmission/reflection measurements and real time atomic force microscopy (AFM) imaging under optical illumination. The results indicate that photo-dissolution occurs in three stages with the extent and kinetics of each stage depending strongly on Ag film thickness. By contrast, the photo-dissolution is found to be independent of As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 matrix thickness. The extent of three stages also depends strongly on the laser dose and can be reduced to two stages at higher laser fluence. A comparative study of two oppositely stacked sample configurations: As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/Ag/glass and Ag/As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/glass show that the heterostructures respond differently to light illumination. For the former, Ag dissolves completely into As〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 matrix at a faster rate than for the latter case. The origin of this difference is established by energy dispersive X-ray spectroscopy and AFM measurements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): V. Prasad, B. Suresh, M. Kostrzewa, Y. Gandhi, A. Ingram, A. Siva Sesha Reddy, V. Ravi Kumar, N. Veeraiah〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dielectric properties of heavy metal oxide glass system 〈em〉viz〈/em〉., PbO-Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-SiO〈sub〉2〈/sub〉 mixed with varied concentration of NiO are studied as functions of frequency and temperature. The dielectric parameters 〈em〉viz〈/em〉., ε′, tan 〈em〉δ〈/em〉, 〈em〉σ〈/em〉〈sub〉〈em〉a〈/em〉.〈em〉c〈/em〉〈/sub〉. are observed to increase with NiO content. Electric moduli formalism is adopted for the analysis of dipolar relaxation effects. Impedance plots drawn for the glasses doped with different NiO concentrations pointed out decreasing value of electrical impedance of the glass samples with increase of NiO content. Activation energies for dipoles and for a.c. conductivity are found to decrease, whereas the concentration of defect energy states 〈em〉N〈/em〉(〈em〉E〈/em〉〈sub〉〈em〉F〈/em〉〈/sub〉) is increased with increase of NiO content. Quantitative analysis of these results along with those of spectroscopic studies indicated that with increase of NiO concentration there is gradual growing presence of Ni〈sup〉2+〈/sup〉modifier (O〈sub〉h〈/sub〉) ions in the glass matrix. As modifiers these ions are anticipated to stimulate structural defects by depolymerizing the glass network. The increasing degree of disintegration of the glass network is predicted to facilitate for diffusion of conducting ions in the bulk glasses. Finally, it is concluded that in spite of the fact that the host glass is a heavy dense glass (composed of multi component heavy metal oxides with low mobile charge carriers) which has got plenty of other applications in optically operated devices, it is more conducive even for easy diffusion of Ni〈sup〉2+〈/sup〉ions that contribute to ionic conductivity. In view of these observations it is concluded that the studied glass may be considered as ionic conducting material to be used in solid electrolytes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Elham Moayedi, Shigeki Sawamura, Jana Hennig, Enrico Gnecco, Lothar Wondraczek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Similar to normal indentation studies, structural compaction and shear flow occur also in the lateral deformation of glass surfaces through scratching. Here, we apply instrumented indentation with tangential displacement in order to study the elastic-plastic regime of scratch-deformation on silica, borosilicate and soda lime silicate glasses. We adopt the protocol of volume recovery analysis by high-temperature annealing to determine variations in geometry and volume of the scratch groove before and after the release of scratch-induced densification. While very similar relative recovery behavior is found for both normal indentation and scratch testing, inherent differences occur in the absolute presence of deformation modes across all three types of glass. In particular, caused by shear deformation at the apex of the employed Berkovich scratch tip, pronounced material pile-up occurs in scratching for normal loads which are about one order of magnitude below reference experiments of normal indentation. This leads to an increase in the effective friction coefficient and a non-trivial correlation between the scratch hardness and the normal hardness of glasses.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Murilo Montesso, Danilo Manzani, José P. Donoso, Claudio J. Magon, Igor D.A. Silva, Mario Chiesa, Elena Morra, Marcelo Nalin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work presents the production and characterization of a new prolific binary glass system based on SbPO〈sub〉4〈/sub〉-GeO〈sub〉2〈/sub〉. The dependence of GeO〈sub〉2〈/sub〉 content on thermal, structural and optical properties were investigated by means of thermal analysis, Raman, UV–Vis-NIR, infrared, M-lines and EPR spectroscopy. Glass transition temperatures remain constant around 410 °C when GeO〈sub〉2〈/sub〉 content is increased, indicating that GeO〈sub〉4〈/sub〉 units are not responsible for increasing the connectivity of PO〈sub〉4〈/sub〉 units. Thermal stability linearly increases as a function of GeO〈sub〉2〈/sub〉 content, reaching a value around 400 °C for glass containing 90 mol% of GeO〈sub〉2〈/sub〉. Raman spectroscopy was used to evaluate the glass structural changes when GeO〈sub〉2〈/sub〉 is incorporated from 30 to 90 mol% indicating a gradual change from a phosphate to a germanate glass skeleton. The optical window extends from 350 nm at UV region, up to 2.7 μm in the middle-infrared region limited by the multiphonon cut-off due to the strong OH absorption. M-lines technique shows that increasing GeO〈sub〉2〈/sub〉 content decreases the refractive index, mainly because the lower concentration of higher polarizable antimony atoms. EPR spectra of heat treated V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 doped glasses, at different temperatures above the glass transition temperature, shows the characteristic eight-line hyperfine splitting spectrum. The spin Hamiltonian parameters obtained from the simulated spectra indicates that the paramagnetic tetravalent vanadium ions in the glasses exist as vanadyl form VO〈sup〉2+〈/sup〉, located in axially distorted octahedral sites. For glasses treated at higher temperatures a second VO〈sup〉2+〈/sup〉 component appears in the EPR spectra and the analysis of the spin-Hamiltonian parameters suggests that these vanadyl ions are in more tetragonal distorted octahedral sites than those in the glass.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): William C. Lepry, Sophia Smith, Showan N. Nazhat〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bioactive, sol-gel derived borate glasses (SGBGs) can rapidly convert to hydroxy-carbonated apatite (HCA) in simulated body fluid (SBF). The processing conditions and compositional changes in four-component glasses have previously been investigated, yet the effect of certain elements, such as sodium, on the processing and bioactivity has not been explored. Therefore, in this study, a borate substituted Bioglass® "45S5" of the formulation (46.1)B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(26.9)CaO-(24.4)Na〈sub〉2〈/sub〉O-(2.6)P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉; mol%, was created as the baseline glass and the amount of sodium was incrementally decreased three times, while maintaining the ratio of the other elements, until a sodium-free, three-component composition was generated (61.0)B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(35.6)CaO-(3.4)P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉; mol%. Decreasing sodium content altered the gelation behaviour, textural properties, and greatly influenced reactivity as measured through gravimetric changes when exposed to water vapour. Furthermore, ion release profiles corresponded with the different glass compositions, however, interestingly, sodium content had very little effect on rate of conversion to HCA in SBF, which was observed to be within 2 h, according to x-ray diffraction, attenuated total reflectance-Fourier-transform infrared spectroscopy, and scanning electron microscopy. This study aims to serve as a basis to develop more simplified SGBG systems for tissue engineering applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Changwei Lin, Jianlei Liu, Lei Han, Hua Gui, Jun Song, Cui Li, Taoyong Liu, Anxian Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Study of 20MgO-20Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-57SiO〈sub〉2〈/sub〉 (MAS) glasses occupies a crucial position for optimizing glass performances for industrial applications. Here, we employed Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 dopant, and successfully prepared series of 20MgO-(20-〈em〉x〈/em〉)Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-57SiO〈sub〉2〈/sub〉-3B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-〈em〉x〈/em〉Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (MASBC) glasses with a doping level, denoted by 〈em〉x〈/em〉, ranging from 0 to 1 mol%, by conventional melt-quenching method. The investigation was systematically conducted using DSC, XRD, IR, optical absorption, electron paramagnetic resonance (EPR) and luminescence techniques. Structural analysis shows that all glass samples are amorphous in nature, and the glass network was mainly identified as the functional groups of [SiO〈sub〉4〈/sub〉] and [AlO〈sub〉4〈/sub〉]. From the optical absorption data, various optical parameters such as optical band gap, Urbach energy, crystal field and Racah parameters can be obtained. Besides, the luminescence and excitated spectra were recorded to confirm the presence of Cr〈sup〉3+〈/sup〉 in a weak crystal field, and the luminescence lifetime was found to decrease with increased Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 due to the dipole interaction between the Cr〈sup〉3+〈/sup〉 pairs (Cr〈sup〉3+〈/sup〉-Cr〈sup〉3+〈/sup〉). The EPR spectra of Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-doped MASBC glass exhibit two resonance signals at g = 5.33 and 1.96, indicating the characteristic of Cr〈sup〉3+〈/sup〉 ions. Subsequently, according to the calculated bonding parameters, we confirm a strong ionic character of glass samples.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Arijit Basak, Lata Ramrakhiani, Sourja Ghosh, Ranjan Sen, Ashis K. Mandal〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chromium doped phosphate glass was melted adopting microwave (MW) heating and properties were compared with conventional glass. Standard methods of characterization adopting X-ray diffraction (XRD), density, UV–Vis-NIR absorption spectroscopy, Refractive indices (RI), Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Photoelectron spectroscopy (XPS), Differential Scanning Calorimetry (DSC) were performed to evaluate the properties of the glasses. XRD analysis confirmed the amorphous nature. Enhanced absorption peaks in UV–Vis spectra at wavelengths 298, 456, 660 and 685 nm suggest higher Cr〈sup〉3+〈/sup〉 concentration in MW prepared glass. Alteration in peak intensities and shift in binding energy in XPS confirm the presence of Cr(III) in different coordination and orientation in glass. Spectrophotometric method developing colour complex of Cr[VI] with 1,5-diphenyl carbazide indicates absence of Cr[VI] in the glass. Presence of IR bands due to different phosphate bonds depicts similar structure in both the glasses. Difference in density, RI, and glass transition temperature (T〈sub〉g〈/sub〉) are also observed in MW melted glass. Maximum instantaneous electrical power was 1.4 kW in MW cavity, whereas 4 kW was recorded in resistive heating furnace. Reflected power remains within 15% of forward power. Total melting time was ~ 2 h in MW heating unlike 6–7 h in resistive heating.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): A. Charlotte Rimbach, Franziska Steudel, Bernd Ahrens, Stefan Schweizer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The glass properties as well as the photoluminescence quantum efficiency of Li〈sub〉2〈/sub〉O-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Li〈sub〉2〈/sub〉O-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 glasses are investigated; both glass systems are optically-activated by the addition of the lanthanide ions Tb〈sup〉3+〈/sup〉, Eu〈sup〉3+〈/sup〉, and Dy〈sup〉3+〈/sup〉. Glass transition, glass crystallization, and glass melting temperatures as well as glass forming temperature ranges are determined upon varying the modifier-to-former (Li〈sub〉2〈/sub〉O-to-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) ratio in the range between 1:6 to 1:2. For lithium borate glass, the risk of spontaneous crystallization decreases upon decreasing the lithium concentration. The photoluminescence quantum efficiency increases slightly upon decreasing the lithium concentration with the value of a Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-containing sample always lower than that of the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-free correspondent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Yuichi Yamamoto, Koya Sato, Kaoru Nakajima, Kenji Kimura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High-resolution elastic recoil detection analysis (HERDA) has been conducted to quantify outermost OH group on a silica glass surface. The results of HERDA showed that the surface number density of OH groups (silanol number) can be measured with a good reproducibility by heating the sample in vacuum to remove the surface adsorbates. The measured silanol number depends on the temperature and is in good agreement with the result reported for porous silicas. Furthermore, by investigating the relationship between the contact angle of water and the silanol number, it was confirmed that the contact angle increases with decreasing silanol number.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Xia Yuhang, Zou Xiangyu, Zhang Hongbo, Zhao Mengjie, Meng Shuo, Su Chunhui, Jing Shao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Eu〈sup〉3+〈/sup〉 doped transparent glass ceramics (GCs) are obtained via melt- quenching technique and subsequent heating. The structure and morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD and SEM results showed that tetragonal barium molybdate (BaMoO〈sub〉4〈/sub〉) crystals are precipitated in the glass matrix. The excitation spectrum of BaMoO〈sub〉4〈/sub〉:Eu〈sup〉3+〈/sup〉 GCs are composed of Eu〈sup〉3+〈/sup〉 ions characteristic excitation peaks. The emission spectra of BaMoO〈sub〉4〈/sub〉:Eu〈sup〉3+〈/sup〉 GCs consists of several sharp emission bands center at 592 nm, 615 nm, 653 nm and 702 nm, respectively. Among them, the strongest one was located at 615 nm due to 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉2〈/sub〉 transition of Eu〈sup〉3+〈/sup〉 generating bright red light. The quantum efficiency of BaMoO〈sub〉4〈/sub〉:Eu〈sup〉3+〈/sup〉 GC is 46.3%, and the fluorescence lifetime is 2.0716 ms, when the Eu〈sup〉3+〈/sup〉 ions doping concentration is 0.7 mol%.The results show that Eu〈sup〉3+〈/sup〉 doped BaMoO〈sub〉4〈/sub〉 glass ceramics exhibit a potential to act as a kind of red phosphor for white light-emitting diodes (W-LEDs).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Zhigang He, Sheng Huang, Kaili Chu, Chaofeng Zhu, Luyue Niu, Xinyu Wu, Xiaohui Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Tb〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉 doped phosphosilicate glasses prepared by melt quenching method are studied for light emitting diode applications. For certain base glass compositions, the crystals Ca〈sub〉3〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉2〈/sub〉 and CaZn〈sub〉2〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉2〈/sub〉 are precipitated during the melt quenching process, which induce the narrowness of the full width at half maximum (FWHM) of the emission bands peaked at 574 nm of Dy〈sup〉3+〈/sup〉 ions. The intensity of emission bands of Tb〈sup〉3+〈/sup〉 ions at 489 and 544 nm is significantly enhanced with the increase of P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 content. The ratio of the emission located at the yellow wavelength portion to that located at the blue wavelength region of the Dy〈sup〉3+〈/sup〉 ions can be apparently tuned by changing the P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 content as well. In addition, the energy transfer between Tb〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉 in the as-prepared glasses is also discussed. The Commission International de I'Eclairage (CIE) chromaticity diagram shows that the emission hue is dependent on the glass composition. The Tb〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉 doped phosphosilicate glasses have promising prospects in light emitting diode applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Yevgeny A. Golubev, Tatyana G. Shumilova, Sergey I. Isaenko, Boris A. Makeev, Alexandr А. Utkin, Elena I. Suvorova, Kord Ernstson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In nature extreme PT-conditions result in numerous glass-like solids, the study of which allows specifying various structural and chemical features of extreme materials, which have a great application potential in various fields of technology. We studied features of nanostructure of natural impact glasses, including recently discovered ultrahigh-pressure high-temperature impact glasses, compared to low-pressure natural and synthetic standard silica glasses. In this paper we presented complex data of atomic force microscopy, X-ray diffraction, X-ray energy-dispersive spectrometry, infrared and Raman spectroscopy. We described nanostructural characteristics of impact glasses and showed influence of chemical composition on the features of their structure. We discovered that the elemental composition was the most important factor determining the glasses nano-heterogeneity. We noted an essential role of influence of Na impurity on glass nanostructure. The impact glasses with pure SiO〈sub〉2〈/sub〉 composition have the smallest sizes of nanostructural elements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Cedrick O'Shaughnessy, Grant S. Henderson, Benjamin J.A. Moulton, Lucia Zuin, Daniel R. Neuville〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present the first Li 〈em〉K〈/em〉-edge XANES study of a varied suite of lithium silicate (LS) and lithium alkaline-earth silicate (LMS) glasses. The LS series contains three glasses with compositions LS4 (20 Li〈sub〉2〈/sub〉O–80 SiO〈sub〉2〈/sub〉), LS2 (33 Li〈sub〉2〈/sub〉O–67 SiO〈sub〉2〈/sub〉) and LS1.5 (40 Li〈sub〉2〈/sub〉O–60 SiO〈sub〉2〈/sub〉) and the LMS series is comprised of four glasses of compositions 20 Li〈sub〉2〈/sub〉O–20 M〈sub〉2〈/sub〉O–60 SiO〈sub〉2〈/sub〉 where M = Mg, Ca, Sr and Ba. The spectra were compared to those of known salts and minerals, particularly to lithium metasilicate (Li〈sub〉2〈/sub〉SiO〈sub〉3〈/sub〉) and lithium carbonate (Li〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉). Crystalline lithium metasilicate has a sharp, strong intensity absorption edge whereas the lithium silicate glasses all have a weak intensity edge feature, similar to that of lithium carbonate (Li〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉). The intensity of the edge is governed by the existence of a 2〈em〉p〈/em〉 electron and can be correlated with the ionicity of the Li〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bond. Therefore, the bonding environment in LS glasses differs considerably from their crystalline counterparts. The area of the absorption edge peak increases with the lithium content of the LS glasses. As for the LMS glasses the edge peak changes drastically depending on the alkaline-earth present. The peak area of the LMS glasses decreases with increasing charge density (Z/r〈sup〉2〈/sup〉) from barium to magnesium. The area of the absorption edge peak in the LS glasses is larger than that of the LMS glasses. Thus, the addition of alkaline-earth elements to lithium silicate glasses modifies the glass network differently depending on the specific element, which in turn creates an altered lithium bonding environment as evidenced by their Li 〈em〉K〈/em〉-edge XANES spectra.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): U. Dahlborg, J.-G. Gasser, G.J. Cuello, S. Mehraban, N. Lavery, M. Calvo-Dahlborg〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The temperature and time dependent structure of molten NiP alloy of eutectic composition has been studied by neutron diffraction. Ni particles were found to exist in the melt at temperatures at least up to about 150 degrees above liquidus. The amount varies reversibly as temperature increases but decays slowly with time. Remarkably, particles still exist even after that the melt has been kept more than 30 h at different temperatures in the molten state. The static structure factor and the pair distribution function obtained at 1050 °C are presented.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Ladislav Koudelka, Oksana Kupetska, Petr Kalenda, Petr Mošner, Lionel Montagne, Bertrand Revel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The glass to crystal transformation was studied for two glasses with composition 25Na〈sub〉2〈/sub〉O·50MoO〈sub〉3〈/sub〉.25P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 and 25Na〈sub〉2〈/sub〉O·50WO〈sub〉3〈/sub〉.25P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉. During the heat treatment process, two crystalline compounds were formed, NaMoO〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉 and NaWO〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉, respectively. Physico-chemical properties of the corresponding glasses and crystals were compared, as well as their Raman and 〈sup〉31〈/sup〉P MAS NMR spectra. Differential thermal analysis revealed crystallization peaks at 483 °C for the Mo-containing glass and at 624 °C for the W-containing glass; melting points of crystalline compounds were determined as 695 ± 2 °C for NaMoO〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉 and 858 ± 2 °C for NaMoO〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉. Sodium tungstate-phosphate glass has lower solubility in comparison with the sodium molybdate-phosphate glass. The study of the crystallization mechanism showed a prevailing surface nucleation. 〈sup〉31〈/sup〉P MAS NMR spectra of the two glasses revealed the same shape and almost the same width, which reflects a similar local environment for P in these glasses. The position of the resonance for W-containing glass at a more negative chemical shift than the Mo-containing one is attributed to the different electrical field strength of W atoms than Mo atoms. 〈sup〉31〈/sup〉P MAS NMR spectra of crystals revealed two resonances at +17 and − 0.5 ppm for the Mo glass and at −0.1 and − 1.9 ppm for the W glass, reflecting the presence of two different phosphorus short range environments, in agreement with their crystal structure. Raman spectra showed similarity in structural features for Mo and W glasses and their isomorphic compounds. Splitting of the dominant Raman bands in the crystal spectra reflects a distortion of MoO〈sub〉6〈/sub〉 and WO〈sub〉6〈/sub〉 octahedra. Raman spectra also suggested the breaking of Mo-O-Mo and W-O-W linkages during crystallization.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): X.B. Zhai, Y.G. Wang, L. Zhu, C.C. Cao, Y.D. Dai, J.K. Chen, F.M. Pan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Atom migration, phase structure and magnetic properties in the Fe〈sub〉82〈/sub〉Si〈sub〉2〈/sub〉B〈sub〉11〈/sub〉P〈sub〉4〈/sub〉Cu〈sub〉1〈/sub〉 amorphous alloy isothermally annealed at various heating rates are investigated. Annealing the samples at a high heating rate promotes the formation of Cu-rich regions and delays the phase separation process to high temperature, which is conductive to increase the volume fraction of the nanocrystalline phase and refine nanograins during the crystallization. When the alloy is isothermally annealed at 758 K for 180 s, the saturation magnetic flux density increases from 1.74 T to 1.79 T and the coercivity decreases from 7.8 A/m to 4.4 A/m with the heating rate increasing from 0.5 K/s to 20 K/s. Meanwhile, it confirms that the occupation of Si atoms in the lattice of 〈em〉bcc〈/em〉-Fe can be suppressed by the annealing with high heating rate. Increasing the heating rate is widely regarded as an effective method to improve soft magnetic properties of Fe-based nanocrystalline alloys. However, it is found that the content of the nonmagnetic atom enriched regions rises with the increase of heating rate, which can reduce the magnetic interaction in the nanocrystalline ribbons. Therefore, the exorbitant heating rate reaching 40 K/s will dramatically promote the aggregation of nonmagnetic atoms and deteriorate the soft magnetic properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Alexander I. Sidorov, Uliana V. Yurina, Gulnaz R. Rakhmanova, Marina N. Shinkarenko, Oleg A. Podsvirov, Yuri K. Fedorov, Alexey V. Nashchekin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The results of experimental study of silver-containing lanthanum-phosphate glasses, modified by electron irradiation with electrons energy 〈em〉E〈/em〉 = 5 and 50 keV and thermal treatment are presented. The concentration of Ag〈sub〉2〈/sub〉O in glasses was 17 and 30 mol%. It is shown that initially silver is contained in glasses mainly in a state of subnanosized neutral molecular clusters (MCs). Local electron irradiation results in the increase of MCs concentration in the irradiated zone. This process is accompanied by the appearance of luminescence outside the irradiated zone. Redistribution of silver during electron irradiation is confirmed by X-ray spectral microanalyses. During irradiation with 〈em〉E〈/em〉 = 5 keV some part of silver migrates to the glass surface, forming the solid silver film. During thermal treatment the growth of silver MCs takes place, and, at last, they form silver nanoparticles (NPs).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): D.V. Sampaio, A. Picinin, Benjamin J.A. Moulton, J.P. Rino, P.S. Pizani, E.D. Zanotto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research we correlate the structural parameters obtained from molecular dynamics (MD) simulations and Raman scattering to construct a self-consistent picture of the glass structure, and its variation from ambient temperature to the supercooled liquid above the glass transition temperature (Tg). The MD results show that the glass structure is composed of SiO〈sub〉4〈/sub〉 tetrahedra and PbO〈sub〉x〈/sub〉 (x = 4, 5) polyhedra. To correlate the Q〈sup〉n〈/sup〉 population obtained from the MD and Raman a second type of Q〈sup〉3〈/sup〉 species is required. The two types of Q〈sup〉3〈/sup〉 species are interpreted as being associated with the bimodal distribution displayed by the Pb〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Si pair correlation function. From a MD snapshot is also shown that the second Q〈sup〉3〈/sup〉 species can have a bridging oxygen bound to a Pb ion. As the temperature increases, depolymerization of the Q〈sup〉n〈/sup〉 speciation is observed and confirmed by the oxygen speciation determined from both Raman and MD. The depolymerization of the silica network is consistent with the non-Arrhenian (fragile) viscosity decrease with temperature and may explain this viscosity behavior.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Nerea Mascaraque, Kristine F. Frederiksen, Kacper Januchta, Randall E. Youngman, Mathieu Bauchy, Morten M. Smedskjaer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium aluminoborate glasses exhibit high resistance to cracking under contact loading, but low hardness and poor chemical durability in aqueous media. On the other hand, alkaline earth aluminoborate glasses feature improved chemical resistance and hardness, but lower resistance to cracking. In this work, we investigate the possibility to simultaneously improve the mechanical and chemical resistance of aluminoborate glasses by mixing alkali and alkaline earth modifiers. We study the mixed Li/Ba and Li/Mg aluminoborate glasses, since Li〈sup〉+〈/sup〉 and Ba〈sup〉2+〈/sup〉 have different charge and size but similar modifier field strength (charge to size ratio), while Mg〈sup〉2+〈/sup〉 has the highest field strength among these modifiers due to its small size. The two glass series will thus give insights into the competitive effects of modifier charge and size on glass structure, mechanical properties, and dissolution rates in acidic, neutral, and basic solutions. The substitution of barium for lithium at fixed [Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉]/[B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉] ratio does not affect the network structure and properties, such as hardness and dissolution rate. However, the substitution of magnesium for lithium leads to an increase in hardness and chemical durability for all pH solutions (2, 7, and 14), likely as a result of the increase in the fractions of five- and six-fold coordinated aluminum species and atomic packing density. The glass with 5 mol% Li〈sub〉2〈/sub〉O and 20 mol% MgO exhibits the best combination of high hardness and low dissolution rate, while maintaining a good crack-resistance comparable to that of the Li-aluminoborate glass. In both mixed glass series, the lowest dissolution rates are measured in neutral solutions, while those in acidic and especially basic media are higher. The structural origins of the trends in chemical and mechanical properties are discussed based on 〈sup〉11〈/sup〉B and 〈sup〉27〈/sup〉Al nuclear magnetic resonance (NMR) spectroscopy measurements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Steve De Pooter, Steven Latré, Frederik Desplentere, David Seveno〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Silica aerogels are considered as promising materials for future energy saving buildings, however, their reliability remains questionable as commercially available aerogels can show relatively high standard deviations e.g. 22.2 ± 1.4 mW m〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉. Therefore a synthesis protocol for silica aerogel powder with thermal conductivities having extremely reduced standard deviations was designed, compatible with mass production, i.e. reduced use of solvents and hydrophobization agents. Silica sols were prepared from non-ion exchanged water glass, while a combined solvent exchange, silylation and washing out of sodium ions was carried out using a hexane/trimethylchlorosilane/isopropyl alcohol solution with a molar ratio trimethylchlorosilane/pore water of only 0.11. The hexane amount was reduced 35 times compared to typical processes in literature. The aerogel powder was finally dried at ambient pressure at 150 °C. No notable shrinkage was observed for 8 wt% silica aerogel samples, having a thermal conductivity of 25.4 mW m〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉 with a standard deviation of only 0.1. The 6 wt% silica aerogels had a thermal conductivity of 23.4 mW m〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉 with a standard deviation of 0.3, but had shrunken 36%. By replacing trimethylchlorosilane with hexamethyldisiloxane, aerogels having a thermal conductivity of 22.4 mW m〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉 with a standard deviation of 0.3 were obtained.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Milad Ghaemi, Rouhollah Tavakoli, Alireza Foroughi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉According to recent studies, Cu〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr and Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr binary alloying systems are very similar based on known glass-forming ability criteria, however, they exhibit significant difference in glass-forming ability in practice. In this work, local atomic structures of Cu〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr and Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr metallic glasses are studied by molecular dynamics simulation to explain the source of mentioned difference. The total and partial distribution functions, coordination number and voronoi analysis are utilized to characterize the local atomic structures around Zr, Ni and Cu atoms. It was found that the local environment around Zr atoms is almost similar in both systems. The difference in the atomic structure in these systems mainly arises from topologies of polyhedra around Cu and Ni atoms. In particular, full icosahedron is one of the most popular local structure in Cu〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr system, while its population is significantly smaller in Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr system with the same composition. Additionally, networks formed by full icosahedra connections, medium range order, are more robust in Cu〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr system. Higher percentage of topologically ordered and compact structures and their connectivity could explain why bulk metallic glass formation is possible in Cu〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr system but not in Ni〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zr system.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Nikolai V. Priezjev, Maxim A. Makeev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The role of porous structure and glass density in the response behavior to compressive deformation of amorphous materials is investigated via molecular dynamics simulations. The disordered, porous structures were prepared by quenching a high-temperature binary mixture below the glass transition point into the phase coexistence region. With decreasing average glass density, the pore morphology in quiescent samples varies from a random distribution of compact voids to complex pore networks embedded in a continuous glass phase. We find that during compressive loading at constant volume, the porous structure is linearly transformed in the elastic regime and the elastic modulus follows a power-law increase as a function of the average glass density. Upon further compression, pores deform significantly and coalesce into large voids leading to formation of domains with nearly homogeneous glass phase, which provides an enhanced resistance to deformation at high strain.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 500〈/p〉 〈p〉Author(s): Mandeep Kaur, Gurbinder Kaur, V. Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present investigation, an attempt has been made to study the effect of La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (X) ratio on the optical properties of the novel glass series xLa〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-(10-x)Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 -15SrO-15CaO -10B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-10Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-40SiO〈sub〉2〈/sub〉 (x = 2, 4, 6, 8). The glasses have been prepared via melt quenching route. Fourier transform infrared spectroscopy (FTIR) has been done to obtain the band positions and functional groups for all the pristine as well as heat treated glasses, respectively. UV-visible spectroscopy has been performed to obtain the band gap, Urbach energy and refractive indices for all the pristine as well as heat treated glasses. The parameters like density/molar volume have been calculated with the varying La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (X) ratio. Also, some theoretical parameters like electronegativity of metal ion/oxide ion, interionic distance, ionic concentration, optical basicity and polarizability have been calculated. The parameters like average cross link density, average force stretching constant, bulk modulus and number of network bonds per unit volume have also been calculated. Furthermore, electron paramagnetic resonance (EPR) spectra have also been obtained for all the glass samples to determine the magnetic behavior as well as g values (spin Hamiltonian parameters). The optical basicity of all the glasses lies within the range of 0.621–0.631. All the pristine glasses exhibit band gap energy ranging from 5.80 to 5.89 eV.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Non-Crystalline Solids, Volume 499〈/p〉 〈p〉Author(s): Olli-Ville Laukkanen, H. Henning Winter〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The temperature dependence of the dynamics of glass-forming liquids can be characterized by the dynamic fragility (〈em〉m〈/em〉) and apparent activation energy (〈em〉E〈/em〉〈sub〉〈em〉a〈/em〉〈/sub〉) at the glass transition temperature 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉. In this study, we derive analytical expressions that allow the calculation of these parameters from a modified Kaelble equation which divides the temperature dependence into two regimes above and below a characteristic temperature 〈em〉T〈/em〉〈sub〉〈em〉d〈/em〉〈/sub〉. Special emphasis is given to the analysis of the 〈em〉T〈/em〉〈sub〉〈em〉d〈/em〉〈/sub〉 parameter that can be considered as the rheological glass transition temperature. Rheological characterization is performed on twenty-seven bitumens originating from various crude oil sources and refining processes. Their dynamic fragilities and apparent activation energies are calculated at the calorimetric 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉 and at 〈em〉T〈/em〉〈sub〉〈em〉d〈/em〉〈/sub〉. Bitumen can be classified as a strong glass-forming liquid, dynamic fragilities varying in the range of 〈em〉m〈/em〉(〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉) = 26 … 52 for the individual bitumen samples. The results indicate that 〈em〉m〈/em〉(〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉) and 〈em〉E〈/em〉〈sub〉〈em〉a〈/em〉〈/sub〉(〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉) are linearly correlated with 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉, and these 〈em〉T〈/em〉〈sub〉〈em〉g〈/em〉〈/sub〉-dependences are unusually strong in comparison to other classes of glass-forming liquids. However, dynamic fragilities and apparent activation energies evaluated at 〈em〉T〈/em〉〈sub〉〈em〉d〈/em〉〈/sub〉 are nearly independent of the type of bitumen and show only a weak dependence on 〈em〉T〈/em〉〈sub〉〈em〉d〈/em〉〈/sub〉.〈/p〉〈/div〉 〈/div〉