ALBERT

Description: Laser machining has great potential for automated manufacturing of parts made of carbon-fiber-reinforced plastic (CFRP) due to the nearly force and tool-wear free processing. The high vaporization temperatures and the large heat conductivity of the carbon fibers, however, lead to unintentional heat conduction into the material causing damage in zones close to the process. In this paper, the matrix damage zone (MDZ) is subdivided into a matrix sublimation zone (MSZ) where the matrix material was sublimated and a zone where the temperature temporarily exceeded a value causing structural damage in the matrix. In order to investigate the extent of these zones, a one-dimensional heat flow model was applied, which was calibrated by cutting experiments using temperature sensors embedded in the CFRP samples. The investigations showed that the extents of the MSZ and MDZ are dominated by a total interaction time, which includes the passage of the laser beam and the continued interaction of the cloud of hot ablation products with the carbon fibers at the kerf wall and that from a practical point of view, the experimentally determined effective heat conductivity is suitable for simple estimations of the heat-affected zones in CFRP.

Description: This paper is concerned with the axial buckling behavior of multi-walled silicon carbide nanotubes (MWSiCNTs) based upon a molecular mechanics model. To this end, the mechanical properties of silicon carbide sheets are obtained according to the density functional theory within the framework of the generalized gradient approximation. Through establishing a linkage between the quantum mechanics and the molecular mechanics, the force constants of the total potential energy are obtained theoretically. A closed-form expression is proposed from which by knowing the chirality of the MWSiCNT, its critical buckling strain can be calculated as quickly and accurately as possible. The effects of chirality and number of walls on the critical buckling strain of MWSiCNTs are carefully investigated. It is concluded that with increasing the number of walls of nanotubes, their stability decreases. The effects of diameter and number of walls on the critical buckling strain of MWSiCNTs under axial load get more pronounced at lower diameters. Besides, it is found that the minimum critical buckling strain is related to nanotubes with \( (n,\frac{n}{2}) \) chiral vectors.

Description: Arrays of diamond photoemitters with silicon-vacancy (SiV) photoluminescent (PL) centers have been produced by epitaxy of CVD diamond inside laser-ablated channels in a-Si mask on single crystal or polycrystalline diamond substrates, the mask also serving as Si-doping source. Strong PL emission from the SiV centers with zero-phonon line at 738.6 nm wavelength (6 nm width, 0.8 ns decay time), localized within the photoemitters, has been measured.

Description: Graphene/nickel composite materials were successfully prepared via a one-step in situ reduction from nickel chloride, graphene oxide, and hydrazine at 80 °C for 3 h. Face-centered cubic Ni nanostructures with uniform size and high dispersion assembled on graphene sheets. Through the measurement of complex relative permittivity and permeability, their microwave absorption properties were evaluated. In comparison with pure Ni nanoparticles and graphene, the composite materials demonstrated much better characteristics of microwave absorption. The lowest reflection loss value of the composites with a thickness of 3 mm can reach −23.3 dB at 7.5 GHz. Our research reveals that graphene/Ni composites are promising microwave absorption materials with desirable absorption properties and reduced material weight.

Description: In this paper, a non-contact method that allows to determine the carrier concentration in CdSe crystals is presented. The method relies on the measurement of the effective infrared absorption coefficient by means of the photothermal infrared radiometry (PTR). In order to obtain the effective infrared absorption coefficient and thermal diffusivity, the frequency characteristics of the PTR signal were analyzed in the frame of a one-dimensional heat transport model for infrared semitransparent crystals. The carrier concentrations were estimated using a theory introduced by Ruda and a recently proposed normalization procedure for the PTR signal. The deduced carrier concentrations of the investigated CdSe crystals are in reasonable agreement with those obtained using Hall measurements and infrared spectroscopy. The method presented in this paper can also be applied to other semiconductors with the carrier concentration in the range of 10 14 –10 17  cm −3 .

Description: The presence of wool fibres in non-woven Alfa fibres sheet was investigated as a mean of improving adhesion of Alfa fibre-reinforced unsaturated polyester composite. FT-IR and Raman spectroscopy results revealed that such improvement could occur by a decrease in the hydrophilic character of the Alfa fibres owing to the presence of wool fibres. Hence, physical and chemical interactions could happen between the reinforcement and the matrix as demonstrated by FT-IR and Raman spectroscopy results. Tensile testing performed on this composite confirmed that such adhesion could occur according to its excellent specific parameters despite of its low tensile strength attributed to a higher fibre to fibre contact of wool fibres.

Description: X-ray fluorescence (XRF) is a well known nondestructive technique. It is also applied to multilayer characterization, due to its possibility of estimating both composition and thickness of the layers. Several kinds of cultural heritage samples can be considered as a complex multilayer, such as paintings or decorated objects or some types of metallic samples. Furthermore, they often have rough surfaces and this makes a precise determination of the structure and composition harder. The standard quantitative XRF approach does not take into account this aspect. In this paper, we propose a novel approach based on a combined use of X-ray measurements performed with a polychromatic beam and Monte Carlo simulations. All the information contained in an X-ray spectrum is used. This approach allows obtaining a very good estimation of the sample contents both in terms of chemical elements and material thickness, and in this sense, represents an improvement of the possibility of XRF measurements. Some examples will be examined and discussed.

Description: Ancient turquoise Persian glazed ceramics, which are well known as Khar-Mohreh, belonged to several centuries ago. In this research, reproduction of ancient glazed bodies was performed, and the products were studied by different techniques. Experimental evaluations were focused on elemental, structural, morphological, and colorimetric characteristics. SEM micrographs illustrated a thin (10 μm) uniform composite glazed layer on a porous composite thicker layer (500 μm). The layers consist of microneedle-shaped and nanospherical particles of copper oxide distributed in an amorphous silicate medium. Modeling of this architecture was used for determination of the visual aspect of the ceramic via the reflectance coefficient. Structural and colorimetric results showed that the shape and distribution of copper oxide particles do not play a crucial role on the color of these ceramics.

Description: In this paper, the discrete random packing and various ordered packings such as tetragonal and hexagonal close packed structures generated by discrete element method and honeycomb, which is manually generated were input as the initial packing structures into the multi-particle finite element model (FEM) to study their densification during compaction, where each particle is discretized as a FEM mesh. The macro-property such as relative density and micro-properties such as local morphology, stress, coordination number and densification mechanism obtained from various initial packings are characterized and analyzed. The results show that the coupling of discrete feature in particle scale with the continuous FEM in macro-scale can effectively conquer the difficulties in traditional FEM modeling, which provides a reasonable way to reproduce the compaction process and identify the densification mechanism more accurately and realistically.

Description: In this work, magnetoresistance of as-grown and annealed n- and p-type modulation-doped Ga 0.68 In 0.32 N y As 1−y /GaAs single quantum well structures with various nitrogen concentrations has been studied. At low temperatures and low magnetic fields, in n-type samples negative and in p-type samples positive, magnetoresistance has been observed. The observed negative magnetoresistance in n-type samples is an indication of enhanced backscattering of electrons due to the weak localization of the electrons as an effect of the N-induced defects. Nitrogen concentration and thermal annealing dependence of the magnetoresistance have been studied for both n- and p-type samples. The observed decrease in the negative magnetoresistance in n-type and enhanced positive magnetoresistance in p-type samples following thermal annealing have been explained by considering thermal annealing-induced improvement of mobility and the crystal quality in N-containing samples. After thermal annealing, the magnitude of negative magnetoresistance decreases and the breaking of the weak localization is achieved at lower magnetic fields in n-type samples. It is observed that as the mobility of the sample increases, critical magnetic field of negative to positive magnetoresistance transition becomes lower.

Description: A perspective is sketched for the field of focused electron beam-induced processing (FEBIP). The FEBIP lithography technique is compared to the very successful resist-based electron beam lithography (EBL) technique. The advantages of FEBIP over EBL are identified, the main advantage being its high spatial resolution. This will enable FEBIP to become an important lithography technique for the fabrication of devices with critical dimension in the range between 1 and 20 nm and serve as a complementary technique to EBL. It will be discussed what needs to be done to achieve this and what the potential applications are.

Description: We report on the dependence of a laser radiation induced ablation process of graphite on the applied pulse duration of ultrashort pulsed laser radiation smaller than 4 ps. The emerging so-called non-thermal ablation process of graphite has been confirmed to be capable to physically separate ultrathin graphitic layers from the surface of pristine graphite bulk crystal. This allows the deposition of ablated graphitic flakes on a substrate in the vicinity of the target. The observed ablation threshold determined at different pulse durations shows a modulation, which we ascribe to lattice motions along the c axis that are theoretically predicted to induce the non-thermal ablation process. In a simple approach, the ablation threshold can be described as a function of the energy penetration depth and the absorption of the applied ultrashort pulsed laser radiation. Based on the analysis of the pulse duration dependence of those two determining factors and the assumption of an invariant ablation process, we are able to reproduce the pulse duration dependence of the ablation threshold. Furthermore, the observed pulse duration dependences confirm the assumption of a fast material specific response of graphite target subsequent to optical excitation within the first 2 ps.

Description: Ion implantation was used to dope Na acceptor into ZnO single crystals. With three mixed implantation energies, uniform depth distribution of Na ion in the surface region (~300 nm) of ZnO bulk crystals is achieved. Via post-implantation annealing, a donor–acceptor pair recombination band is identified in the low-temperature photoluminescence spectra, from which the energy level of Na-related acceptor in single crystalline ZnO is estimated to be 300 meV. A p–n junction based on this ZnO–Na layer shows rectifying characteristics, confirming the p-type conductivity.

Description: The femtosecond laser color marking stainless steel surfaces with different incident wavelengths were investigated theoretically and experimentally. It indicates that the spectral regions of the colors firstly increase and then reduce with increasing spatial periods of the ripples induced by laser irradiation. Additionally, the colors are gradually changed from blue to red due to the elongation of the diffracted light wavelengths. As a result, the color effects are distinctly different. This study offers a new controllable parameter to produce diverse colors, which may find a wide range of applications in the laser color marking, art designing and so on.

Description: Tuning charge transport in the bottom-contact pentacene-based organic thin-film transistors (OTFTs) using a MoO x capping layer that serves to the electron–phonon coupling modification is reported. For OTFTs with a MoO x front gate, the enhanced field-effect carrier mobility is investigated. The time domain data confirm the electron-trapping model. To understand the origin of a mobility enhancement, an analysis of the temperature-dependent Hall-effect characteristics is presented. Similarly, the Hall-effect carrier mobility was dramatically increased by capping a MoO x layer on the pentacene front surface. However, the carrier concentration is not affected. The Hall-effect carrier mobility exhibits strong temperature dependence, indicating the dominance of tunneling (hopping) at low (high) temperatures. A mobility enhancement is considered to come from the electron–phonon coupling modification that results from the contribution of long-lifetime electron trapping.

Description: Amorphous Se 85− x Te 15 Sb x ( x  = 2.5, 5 and 7.5 at.%) thin films were deposited on glass substrates by thermal evaporation. The absorption coefficient was determined from the transmittance, and reflectance spectra in the wavelength range 400–2500 nm. Various optical constants have been calculated for the studied compositions. The mechanism of the optical absorption follows the rule of non-direct transition. It was found that the optical energy gap, E g , decreases from 1.42 to 1.36 eV with increasing Sb content from 2.5 to 7.5 at.%. These results can be interpreted on the basis of the chemical bond approach proposed by Bicermo and Ovshinsky. On the other hand, the optical constants such as refractive index, n , and extinction coefficient, K ex , of the films were studied. The dispersion of the refractive index was discussed in terms of single-oscillator Wemple–DiDomenico model. The influence of Sb content on the structure for the annealed films was investigated using X-ray diffraction (XRD) and scanning electron microscopy. The average particle size of the crystalline size for Te 0.04 Se 0.96 phase deduced from XRD pattern. This average decreases with increasing Sb content.

Description: In the present work, Ag y :TiN x thin films, obtained by reactive DC magnetron sputtering, with decreasing [N]/[Ti] atomic ratios (from 1 to 0.1) and a fixed amount of Ag pellets placed in the erosion zone of a pure Ti target, were studied envisaging their application as biopotential electrodes. The strongly under-stoichiometric samples, [N]/[Ti] = 0.1 and 10 at.% Ag; [N]/[Ti] = 0.2 and 8 at.% Ag, were found to be composed of a N-doped hcp-Ti structure, with possible formation of TiAg or Ti 2 Ag intermetallics. These samples exhibit high electrical resistivity values and low hardness and reduced modulus. In the set of samples indexed to a transition zone, [N]/[Ti] = 0.3 and 15 at.% Ag; [N]/[Ti] = 0.7 and 32 at.% Ag, a hcp-Ti to fcc-TiN phase transformation took place, giving rise to a disaggregated N-deficient TiN matrix. It correlates with the high resistivity values as well as the higher hardness and reduced modulus values that were obtained. The last identified zone comprised the stoichiometric Ag:TiN x sample—[N]/[Ti] = 1 and 20 at.% Ag. Extensive metallic Ag segregation was detected, contributing to a significant decrease of the resistivity and hardness values.

Description: The periodical removal of biodeteriogens is a fundamental need for the preservation of outdoor stone cultural heritage, which is stimulating significant efforts toward the development of low-impact conservation strategies. In the present work, the potential of laser removal of Verrucaria nigrescens Pers. from Carrara marble and the evaluation of the associated biocide effect on the organism residues embedded in the surface texture and through the outer porosities of the stone substrate were investigated. The fundamental wavelength of Nd:YAG laser (1,064 nm), commonly used in stone cleaning, and its second harmonic (532 nm) were comparatively tested. The phenomenology of laser treatments carried out in different irradiation conditions was characterized using optical, epifluorescence, and electron microscopes along with chlorophyll fluorescence with pulsed amplitude-modulated imaging. The results achieved show that 532 nm can provide significant advantages with respect to 1,064 nm. The potential of the latter against the biodeteriogens appears rather limited because of the low optical absorption, whereas the former can allow effective and practicable laser treatments, which disclose a significant application perspective.

Description: The photovoltaic behaviour of metal/n-InGaN Schottky junction solar cells with low- and high-level injection conditions are explored by using voltage model. Four metals Ni–Au, Ni, Au and Pt are used as Schottky contact with n-InGaN and Schottky junction solar cell studied for open-circuit voltage ( V oc ) and short circuit current density ( J sc ) with a variation of Indium composition in n-InGaN. The cut-off value of Indium composition in n-InGaN is 36, 42, 55 and 70 % for Ni–Au, Ni, Au and Pt, respectively. The effects of doping density and surface recombination velocity on V oc and J sc are also explored. Model predict increment in V oc and J sc under high-level injection condition as compared to low-level injection condition with ϕ  = 2 × 10 17  cm −2  s −1 photon flux. The metal, Pt, is found to be a better choice in terms of making Schottky junction with n-InGaN. The concentration of donor atoms in n-InGaN plays an important role in both types of injection. The donor concentration should preferably be kept higher (〉10 16  cm −3 ) to get higher V oc .

Description: BiVO 4 nanocrystals coupled with Ag nanoparticles (Ag–BiVO 4 heterogeneous nanostructures) have been prepared by a new strategy via combining a hydrothermal route with a polyol process, in which BiVO 4 nanocrystals were first synthesized by a hydrothermal route, and then, Ag nanoparticles were grown on the surfaces of the presynthesized BiVO 4 nanocrystals through a polyol process. The photocatalytic evaluations demonstrate that BiVO 4 nanocrystals coupled with Ag nanoparticles exhibit the enhanced visible-light-driven photocatalytic activity for the degradation of methylene blue (MB) and rhodamine B (RhB). The energy alignment and diffuse reflectance property of Ag–BiVO 4 heterogeneous nanostructures demonstrate that Ag nanoparticles attached on the surfaces of BiVO 4 nanocrystals play double roles for the enhanced visible-light-driven photocatalytic activity. First, the Ag nanoparticles grown on the surfaces of BiVO 4 nanocrystals may act as electron sinks to retard the recombination of the photogenerated electrons and holes in BiVO 4 so as to improve the charge separation on its surfaces. Second, the Ag nanoparticles increase the visible light absorption of the Ag–BiVO 4 photocatalyst due to surface plasmon resonance (SPR) of Ag nanoparticles. These double roles of Ag nanoparticles make Ag–BiVO 4 heterogeneous nanostructures to exhibit the enhanced photocatalytic activity to decompose MB and RhB under visible light irradiation, compared to the pure BiVO 4 nanocrystals. The enhanced photocatalytic activity is attributed to the charge transfer from BiVO 4 to the attached Ag nanoparticles as well as SPR absorption of Ag nanoparticles. The present work not only provides an efficient route to enhance visible-light-driven photocatalytic activity of BiVO 4 , but also offers a new strategy for fabricating metal–semiconductor heterogeneous nanostructure photocatalysts, which are expected to show considerable potential applications in solar-driven wastewater treatment and water splitting.

Description: In the present work, graphene oxide (GO) was prepared by hummers method from natural graphite and modified with iron oxide nanoparticles. The structural order and textural properties of the graphene-based materials were studied by TEM, XRD, TG-DTA and FT-IR. Hydrogen adsorption measurements have been carried out at 77 or 87 K, and atmospheric pressure on graphene oxide and Fe 3 O 4 –graphene oxide materials. Hydrogen adsorption at 77 K and atmospheric pressure reached values in the order of 1.7 and 2.1 wt% for graphene oxide and Fe 3 O 4 –graphene oxide materials, respectively. The hydrogen adsorption capacities of the Fe 3 O 4 –graphene oxide materials compare favorably well with those attained with high-value carbon materials. The isosteric heat of adsorption ( Q st ) was investigated as a function of hydrogen uptake at 77 and 87 K over the pressure range of 0 to atmospheric pressure. The isosteric heat of adsorption for magnetic GO (9.7 kJ mol −1 ) was found to be higher than for GO (6.1 kJ mol −1 ).

Description: In this paper, we explain the problem of dramatic OFF-state leakage in junctionless tunnel field effect transistor (JLTFET) for a channel thickness greater than 10 nm. In JLTFET, with channel width greater than 10 nm, the depletion region primarily remains confined below the dielectric–semiconductor interface. Hence, we tend to incur significant leakage through the center of the device. With the help of 2D device simulations, we demonstrate that the cause of the leakage current is predominantly due to thermal injection in the source region and is concentrated through the center of the device. We suggest a technique of using a lightly doped source region, below the p-gate to increase the barrier and prevent any leakage. The proposed alteration records an improved I ON / I OFF ratio for JLTFET for a channel of width 20 nm.

Description: The p-electrode of blue light-emitting diodes (LED) chips has a low transmittance on the blue light spectrum. The blue light emitted from the quantum wells under the p-electrode will be severely absorbed by p-electrode, which cause a decrease in blue light extraction efficiency (LEE). In this study, we first designed a current blocking layer (CBL) structure with the blue light reflection through the simulation software. The simulation results show that this structure can effectively improve blue LEE, and then, this structure was verified by experiment. Electroluminescence measurement results show that LED with Metal-distributed Bragg reflector (M-DBR) CBL exhibited better optical performance than the LED with SiO 2 CBL and DBR CBL. It was found that M-DBR CBL can effectively increase the blue light reflectivity and prevent the light absorption from the metal p-electrode to improve LED’ blue LEE.

Description: Three historical manuscripts, two on parchment (dated 1280 and 1514) and one on paper support (dated 1589–1592), were under study. The three manuscripts were strongly attacked by microorganisms exhibiting dark brownish stains all over the surface except in the adjacent areas to some of the used inks, where a halo around the written text could be observed. In order to understand the origin of these halos, inks and manuscript supports were analyzed using portable energy-dispersive X-ray spectroscopy. Characteristic elements (Fe, Cu, Zn, and Mn) from iron gall inks were identified. Inks surrounded by a halo had in common a high amount of Zn in their composition. Microbiologic assays were performed aseptically on collected samples from the areas of the document with significant contamination and degradation. Samples were inoculated in a selective culture media, and the microorganisms developed were identified according to the macroscopic and microscopic features. For the evaluation of microflora proliferation, scanning electron microscopy was used. Furthermore, in vitro tests were carried out in the presence of zinc sulfate, revealing inhibition capacity for the majority of fungi sampled from these manuscripts.

Description: Porous Co 3 O 4 microrods have been prepared by an ultrasound-assisted route with subsequent calcination. The as-prepared Co 3 O 4 microrods are composed of interconnected nanoparticles with porous characteristics. The ultrasonic irradiation is critical to determine the morphology and the electrochemical performance of the products. When tested as anode material for lithium-ion battery, the porous Co 3 O 4 microrods show improved capacity and rate cycling performance. The reversible capacity of the materials retains 678 (±5) mAh g −1 after 50 cycles at 100 mA g −1 . Even when cycled at various rate for more than 50 cycles, the reversible capacity recovers to 600 (±5) mAh g −1 for the current of 100 mA g −1 . The improved lithium-storage performance can be attributed to the reduced electrochemical reaction resistance due to the unique porous architecture of Co 3 O 4 microrods.

Description: We have fabricated transparent thin-film transistors with ZnSnLiO as active layers deposited by radio frequency magnetron sputtering at room temperature. The TFTs structure used in this study was a staggered bottom-gate, which consists of SiO 2 as a gate insulator and heavily doped p-type Si(1 1 1) as a gate electrode. In order to optimize the performance of the ZnSnLiO thin-film transistors, the thermal annealing is investigated. We find that appropriate annealing temperature is very beneficial for the ZnSnLiO TFTs, and when the annealing temperature is 500 °C, the transistor exhibited the high field-effect mobility of 45.1 cm 2 /V s and a large I on/off ratio of 6.0 × 10 7 .

Description: An efficient approach for enhancing the surface antireflection is proposed, in which a black silicon is fabricated by a femtosecond laser in alkaline solution. In the experiment, 2 wt% NaOH solution is formulated at room temperature (22 ± 1 °C). Then, a polished silicon is scanned via femtosecond laser irradiation in 2 wt% NaOH solution. Jungle-like microstructures on the black silicon surface are characterized using an atomic force microscopy. The reflectance of the black silicon is measured at the wavelengths ranging from 400 to 750 nm. Compared to the polished silicon, the black silicon can significantly suppress the optical reflection throughout the visible region (〈5 %). Meanwhile, we also investigated the factors of the black silicon, including the femtosecond laser pulse energy and the scanning speed. This method is simple and effective to acquire the black silicon, which probably has a large advantage in fast and cost-effective black silicon fabrication.

Description:    In this report, we study crystallization and Raman spectral and transmission electron microscopy (TEM) changes in amorphous and nanocrystalline Si. Micro-Raman spectra combined with TEM show that considerable crystallization occurs in a-Si:H and a-Si(Al) (the structure of aluminum-diffused amorphous Si/Al/c-Si), but no additional crystallization was observed for nc-Si:H, after the exposure to a laser or accelerating electrons. Meanwhile, moving toward lower or higher energy for a-Si:H and nc-Si:H, by contrast, the Raman shift appeared for a-Si(Al) as if it were for single-crystalline Si, in which it remained constant at one energy, as the laser intensity increased or decreased. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6781-1 Authors Jong H. Lyou, College of Science and Technology, Korea University, Chungnam, 339-700 South Korea Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Nickel is an important sheath material for the fabrication of MgB 2 wires. However, the effects of Ni doping on the phase formation and superconducting properties of MgB 2 remain controversial. In this work, Ni powder is selected for doping in MgB 2 bulk in order to examine the corresponding changes. Combining with the DSC analysis and in-situ XRD results, we find indications that the Ni powder reacted with Mg and B, forming MgNi 2.5 B 2 at 600°C. The ternary compound began to decompose at a temperature above 800°C. The reactive phase, MgNi 2.5 B 2 , acted as an obstacle to the supercurrent flow, creating weak links among the MgB 2 grain boundaries. However, it is found that the added Ni formed a eutectic liquid phase with Mg at 506°C. The liquid phase helps the formation of MgB 2 at low temperature, which not only increases the density of the sample, but also improves the grain connectivity. Consequently, the presence of Ni in the MgB 2 sample is not necessarily a disadvantage; it depends on the desired application. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-6812-y Authors Qian Zhao, Tianjin Key Lab of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin, 300072 P.R. China Yongchang Liu, Tianjin Key Lab of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin, 300072 P.R. China Qi Cai, Tianjin Key Lab of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin, 300072 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We describe a novel ion-implantation method for fabricating a dichroic nanoparticle film by controlling the nucleation and growth of silver nanoparticles in fused silica. We first implant Sc and O ions into the silica substrate to create a high-index layer and modify the short- and intermediate-range order; this dual-implantation technique defines a sharper interface between the silica substrate and the nanoparticle layer. By modifying the short- and intermediate-range order in a thin layer of the silica matrix, Ag ions that are subsequently implanted are subject to altered diffusion and nucleation dynamics, yielding a bilayer structure comprising spatially separated regions of smaller and larger Ag nanoparticles. Depending on the implanted dose of Sc, the peak resonant wavelength in reflectivity can shift as much as 100 nm between front-side (implanted face) and back-side (non-implanted face) illumination. Implications for the optimization of bidirectional optical filters and optical cavities are discussed and compared to calculations of scattering efficiency based on Mie theory. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-6827-4 Authors R. H. Magruder, Department of Chemistry and Physics, Belmont University, Nashville, TN 37212, USA S. Robinson, Department of Chemistry and Physics, Belmont University, Nashville, TN 37212, USA C. Smith, Department of Chemistry and Physics, Belmont University, Nashville, TN 37212, USA A. Meldrum, Department of Physics, University of Alberta, Edmonton, AB T6G 2J1, Canada R. F. Haglund, Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Most previous studies have employed surface patterning to improve the performance of lubrication systems. However, few have experimentally analyzed improved effects on friction reduction in SiC mechanical seals by ultra-fast laser pulse texturing. This work applies surface texturing on a non-contact mechanical seal and analyzes the characteristics of the resultant surface morphology. A femtosecond laser system is employed to fabricate micro/nanostructures on the SiC mechanical seal, and generates microscale-depth stripes and induces nanostructures on the seal surface. This work examines the morphology and cross section of the SiC nanostructures that correspond to the different scanning speeds of the laser pulse. Results show that varying the scanning speed enables the application of nanostructures of different amplitudes and widths on the surface of the seal. The friction coefficient of the introduced SiC full-textured seal is about 20% smaller than that of a conventional SiC mechanical seal. Hence, femtosecond laser texturing is effective and enables direct fabrication of the surface micro/nanostructures of SiC seals. This technique also serves as a potential approach to lubricating applications. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6822-9 Authors Chien-Yu Chen, Department of Materials Science and Engineering, National Cheng Kung University, No. 1, University Road, Tainan, 70101 Taiwan, R.O.C. Chung-Jen Chung, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, 70101 Taiwan, R.O.C. Bo-Hsiung Wu, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, 70101 Taiwan, R.O.C. Wang-Long Li, Department of Materials Science and Engineering, National Cheng Kung University, No. 1, University Road, Tainan, 70101 Taiwan, R.O.C. Chih-Wei Chien, Laser Application Technology Center, ITRI South, Industrial Technology, Research Institute, Tainan, 73445 Taiwan, R.O.C. Ping-Han Wu, Laser Application Technology Center, ITRI South, Industrial Technology, Research Institute, Tainan, 73445 Taiwan, R.O.C. Chung-Wei Cheng, Laser Application Technology Center, ITRI South, Industrial Technology, Research Institute, Tainan, 73445 Taiwan, R.O.C. Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Advanced applications of glass span the range from biomedical technology to special optical lenses to mobile phones and computers. Such advanced applications demand high-precision machining, which is like multiple single scratches occurring simultaneously on the glass surface. However, in spite of the wealth of literature on scratch deformation behavior of glass there is no significant information available on whether the nanomechanical properties are affected inside the scratch grooves. Therefore, nanoindentation experiments were deliberately conducted at a fixed load of 100 mN through the scratch grooves made at various applied normal loads (5–15 N) at a constant speed of 200 μm s −1 on polished soda–lime–silica (SLS) glass slides. The results showed that depending upon the applied normal load used to generate the scratch grooves, the nanohardness and Young’s modulus inside the scratch grooves decreased by about ∼30–60% from the corresponding data of the undamaged SLS glass due to the presence of sub-surface shear deformation and microcracking as observed by optical, scanning and field emission scanning electron microscopy. A model for microcracked brittle solids was utilized to explain these results. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6828-3 Authors Payel Bandyopadhyay, CSIR—Central Glass and Ceramic Research Institute, Kolkata, 700032 India Arjun Dey, CSIR—Central Glass and Ceramic Research Institute, Kolkata, 700032 India Sudakshina Roy, CSIR—Central Glass and Ceramic Research Institute, Kolkata, 700032 India Nitai Dey, CSIR—Central Glass and Ceramic Research Institute, Kolkata, 700032 India Anoop Kumar Mukhopadhyay, CSIR—Central Glass and Ceramic Research Institute, Kolkata, 700032 India Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The introduction of porosity into ferroelectric ceramics has been of great interest in recent years. In particular, studies of porous lead-zirconate-titanate ceramic (PZT) have been made. In the research reported, samples of Ferroperm Pz27 with porosities of 20, 25 and 30% were studied. Very complete measurements were made of all of the physical properties relevant for ferroelectric applications including thermal conductivity and diffusivity, heat capacity, dielectric, pyroelectric, piezoelectric and elastic properties. Scanning electron micrographs indicated a change from 3-0 to 3-3 connectivity with increasing porosity. Although most of the physical properties are degraded by the presence of porosity, both piezoelectric and pyroelectric figures-of-merit are improved because of the markedly reduced relative permittivity. Porous ferroelectric ceramics are very promising materials for a number of applications. Content Type Journal Article Category Invited paper Pages 1-8 DOI 10.1007/s00339-012-6846-1 Authors Sidney B. Lang, Department of Chemical Engineering, Ben-Gurion University of the Negev, 84105 Beer Sheva, Israel Erling Ringgaard, Meggitt Sensing Systems, Hejreskovvej 18A, 3490 Kvistgård, Denmark Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    CdS quantum dot (QD) sensitized TiO 2 nanorod array (NRA) film electrodes with different rod geometries were fabricated via a solvothermal route followed by a sequentialchemical bath deposition (S-CBD) process. By controlling the solution growth conditions, the rod geometries, especially the tip structures, of the TiO 2 NRAs were tuned. The results indicated that the vertically aligned hierarchical NRAs possessed conically shaped tip geometry, which was favorable for film electrodes due to the reduced reflectance, enhanced light harvesting, fast charge-carrier separation and transfer, suppression of carrier recombination, sufficient electrolyte penetration and subsequent efficient QD assembly. CdS QD sensitized TiO 2 NRA film electrodes with tapered tips exhibited an enhanced photoelectrochemical (PEC) performance, a photocurrent intensity of 5.13 mA/cm 2 at a potential of 0 V vs. saturated calomel electrode, an open-circuit potential of −0.68 V vs. saturated calomel electrode and an incident photon to current conversion efficiency (IPCE) of 22% in the visible-light region from 400 to 500 nm. The effects of rod geometry on the optical absorption, reflectance, hydrophilic properties and PEC performance of bare TiO 2 and CdS QD sensitized TiO 2 NRA film electrodes were investigated. The mechanism of charge-carrier generation and transfer in these CdS QD sensitized solar cells based on vertically aligned TiO 2 nanorods is discussed. Content Type Journal Article Pages 1-11 DOI 10.1007/s00339-012-6825-6 Authors Jing Zhou, State Key Laboratory of Silicon Materials & Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 P.R. China Bin Song, Department of Physics, Zhejiang University, Hangzhou, 310027 P.R. China Gaoling Zhao, State Key Laboratory of Silicon Materials & Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 P.R. China Weixia Dong, State Key Laboratory of Silicon Materials & Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 P.R. China Gaorong Han, State Key Laboratory of Silicon Materials & Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Previously we have reported the existence of small-amplitude charge pulses in crosslinked Polyethylene (XLPE) and epoxy resin with a mobility several orders of magnitude higher than that found for the incoherent charge transport relevant to the steady state current. Here the relationship of this phenomenon to mechanical relaxation in the material is investigated by using a series of epoxy resin nanocomposites based on a resin that has its flexibility increased above that of the fully cured glassy epoxy network by the addition of a suitable flexibilizing chemical. Differential Scanning Calorimetry (DSC) measurements show that the stiffness of the nanocomposite is progressively increased as the nanoparticle concentration increases. Pulsed Electro-Acoustic (PEA) measurements reveal that both positive and negative fast charge pulses exist in the unfilled epoxy at 45 and 70°C under a field of 10 kV/mm with mobility 5×10 −10 to 9×10 −10 m 2  V −1  s −1 , amplitude between 2×10 −5 and 3.6×10 −5 C m −2 and repetition rates between 8 and 12 s −1 . These values are reduced progressively as the nanoparticle concentration is increased from 0% in the unfilled epoxy. A  β -mode mechanical relaxation is identified in the loss modulus by Dynamical Mechanical Analysis (DMA), whose activation energy moves to higher values with increasing nanoparticle concentration. It is shown that the repetition rates of both positive and negative pulses have similar values and are correlated with the β -mode activation energy; a similar correlation is found for the activation energy of the mobility of positive pulses. The correlation of the activation energy of the mobility of negative pulses and that of the β -mode is weaker although both show a progressive increase with nanoparticle concentration. The modification of the fast charge pulse properties by the mechanical stiffness of the epoxy nanocomposite is discussed in terms of the theory presented previously for their formation and transport. Content Type Journal Article Category Invited paper Pages 1-13 DOI 10.1007/s00339-012-6845-2 Authors G. C. Montanari, LIMAT-DIE, University of Bologna, Bologna, Italy M. Xu, LIMAT-DIE, University of Bologna, Bologna, Italy D. Fabiani, LIMAT-DIE, University of Bologna, Bologna, Italy L. A. Dissado, Department of Engineering, University of Leicester, Leicester, UK Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The electrocaloric effect (ECE) of poly (vinyledene fluoride–trifluoroethylene) (P(VDF–TrFE)) 55/45 mol% copolymers was directly measured, which confirms the results deduced from Maxwell relation. The adiabatic temperature change Δ T under a given electric field peaks at the ferroelectric–paraelectric (FE–PE) transition. Away from it, ECE becomes small. Δ T versus applied electric field can be described well by a modified Belov–Goryaga equation. The ECE in ferroelectric polymers, especially near FE–PE transition where larger ECE is observed, are analyzed under different boundary conditions employing phenomenological theory and constitutive equations. The secondary pyroelectricity is found to play a significant role which enhances ECE in ferroelectric polymers. Content Type Journal Article Category Invited paper Pages 1-8 DOI 10.1007/s00339-012-6830-9 Authors S. G. Lu, Materials Research Institute and Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA B. Rozic, Jozef Stefan Institute, 1000 Ljubljana, Slovenia Q. M. Zhang, Materials Research Institute and Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Z. Kutnjak, Jozef Stefan Institute, 1000 Ljubljana, Slovenia R. Pirc, Jozef Stefan Institute, 1000 Ljubljana, Slovenia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Surface photovoltage is used to study the dynamics of photogenerated carriers which are transported through a highly interconnected three-dimensional network of indium phosphide nanowires. Through the nanowire network charge transport is possible over distances far in excess of the nanowire lengths. Surface photovoltage was measured within a region 10.5–14.5 mm from the focus of the illumination, which was chopped at a range of frequencies from 15 Hz to 30 kHz. Carrier dynamics were modeled by approximating the nanowire network as a thin film, then fitted to experiment suggesting diffusion of electrons and holes at approximately 75% of the bulk value in InP but with significantly reduced built-in fields, presumably due to screening by nanowire surfaces. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-6810-0 Authors Andrew J. Lohn, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA Nobuhiko P. Kobayashi, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    This work studies the resonant behavior of nanoscale magnetic materials. This behavior, henceforth referred to as magnetostatic resonance, occurs at frequencies where the permeability is negative and the particle is much smaller than the wavelength. A surface integral equation is formulated on the boundary of the particle to calculate the resonance frequencies and modes. Unique physical properties of these resonances such as scale invariance of resonance frequency and orthogonality properties of resonant modes are studied. A numerical technique is presented to calculate the magnetostatic resonance frequencies of an arbitrary shape. Possible applications of these phenomena are outlined. Content Type Journal Article Category Invited paper Pages 1-4 DOI 10.1007/s00339-012-6767-z Authors A. Kabiri, School of Engineering and Applied Sciences, Harvard University, Harvard, MA 02138, USA L. Talbi, Department of Electrical and Computer Engineering, University of Quebec, Quebec, Canada O. M. Ramahi, Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, Canada Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    In holographic femtosecond laser processing, diffractive parallel pulses are distorted by phase discontinuities and mutual interference between the neighborhoods in the reconstructed image of a Fourier computer-generated hologram when the interval is smaller than the beam diameter. We investigated holographic fabrication on a glass surface using parallel pulses with different intervals. We found the closest parallel pulses with sufficient separation to avoid mutual interference in holographic femtosecond laser processing. The minimum interval was 2.8 times larger than the diffracted beam diameter. The experimental results were also supported by a computer simulation. Our findings will be very useful in the design of holographic laser processing systems. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6801-1 Authors Yoshio Hayasaki, Center for Optical Research and Education, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, 321-8585 Japan Maki Nishitani, Institute of Technology and Science, The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima, 770-8506 Japan Hidetomo Takahashi, Institute of Technology and Science, The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima, 770-8506 Japan Hirotsugu Yamamoto, Institute of Technology and Science, The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima, 770-8506 Japan Akihiro Takita, Center for Optical Research and Education, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, 321-8585 Japan Daichi Suzuki, Center for Optical Research and Education, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, 321-8585 Japan Satoshi Hasegawa, Center for Optical Research and Education, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, 321-8585 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Ag:ZnO hybrid nanostructures were successfully prepared by a twice arc discharge method in liquid. The visible light photocatalytic activities were successfully demonstrated for the degradation of Rhodamine B (Rh. B), Methyl orange (MO), and Methylene blue (MB) as standard organic compounds under the irradiation of 90 W halogen light for 2 h. The Ag:ZnO nanostructures were characterized by X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible absorption spectroscopy (UV-Vis). The results revealed that the Ag:ZnO nanostructures extended the light absorption spectrum toward the visible region and significantly enhanced the Rh. B photodegradation under visible light irradiation. 3 mM Ag:ZnO nanostructures exhibited highest photocatalytic efficiency. It has been confirmed that the Ag:ZnO nanostructures could be excited by visible light ( E 〈3.3 eV). The significant enhancement in the Ag:ZnO nanostructures photocatalytic activity under visible light irradiation can be ascribed to the effect of physisorbed noble metal Ag by acting as electron traps in ZnO band gap. A mechanism for photocatalytic degradation of organic pollutant over Ag:ZnO photocatalyst was proposed based on our observations. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-6797-6 Authors Ali Akbar Ashkarran, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, P.O. Box: 14665-678, Tehran, Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We characterized the conduction mechanisms in thin sputtered films of three representative binary Me–O (Me=Ta, W, and Nb) systems as a function of oxygen content, by combining in situ chemical state and electronic band structure studies from X-ray photoemission with temperature-dependent transport measurements. Despite certain differences, these amorphous films all displayed Fermi glass behavior following an oxidation-induced transition from metallic to hopping conduction, down to a sub-percolation threshold. The electron localization estimated from the band structure was in good agreement with that from the transport measurements, and the two were used to construct phase diagrams of conduction in the degree of oxidation-conductivity coordinates, which should prove important in the design of resistive switching and other electronic devices. Content Type Journal Article Category Invited paper Pages 1-11 DOI 10.1007/s00339-012-6856-z Authors I. Goldfarb, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA F. Miao, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA J. Joshua Yang, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA W. Yi, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA J. P. Strachan, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA M.-X. Zhang, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA M. D. Pickett, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA G. Medeiros-Ribeiro, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA R. Stanley Williams, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, CA 94304, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The role of defects in the room temperature ferromagnetism of the Co–ZnO based diluted magnetic semiconductor (DMS) was investigated by co-doping the DMS with Na. The structure characterizations indicate that both Na and Co ions enter into the ZnO lattice without the formation of secondary phase. The oxygen vacancy of ZnCoNaO increased while the carrier concentration decreased compared with that of ZnCoO, leading to the enhancement of the ferromagnetic property in the ZnCoNaO. The observed ferromagnetism introduced by Na ions is attributed to the exchange interaction via the electron trapped oxygen vacancies coupled with the magnetic Co ions. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-6824-7 Authors Hao Gu, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 China Yinzhu Jiang, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 China Yongbing Xu, York Laboratory of Spintronics and Nanodevices, Department of Electronics, The University of York, York, YO10 5DD UK Mi Yan, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Ferro- or piezoelectrets are dielectric materials with two elastically very different macroscopic phases and electrically charged interfaces between them. One of the newer piezoelectret variants is a system of two fluoroethylenepropylene (FEP) films that are first laminated around a polytetrafluoroethylene (PTFE) template. Then, by removing the PTFE template, a two-layer FEP structure with open tubular channels is obtained. After electrical charging, the channels form easily deformable macroscopic electric dipoles whose changes under mechanical or electrical stress lead to significant direct or inverse piezoelectricity, respectively. Here, different PTFE templates are employed to generate channel geometries that vary in height or width. It is shown that the control of the channel geometry allows a direct adjustment of the resonance frequencies in the tubular-channel piezoelectrets. By combining several different channel widths in a single ferroelectret, it is possible to obtain multiple resonance peaks that may lead to a rather flat frequency-response region of the transducer material. A phenomenological relation between the resonance frequency and the geometrical parameters of a tubular channel is also presented. This relation may help to design piezoelectrets with a specific frequency response. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6848-z Authors Ruy Alberto Pisani Altafim, Department of Electrical Engineering, Engineering School of São Carlos, University of São Paulo, São Carlos, SP, Brazil Ruy Alberto Corrêa Altafim, Department of Electrical Engineering, Engineering School of São Carlos, University of São Paulo, São Carlos, SP, Brazil Xunlin Qiu, Applied Condensed-Matter Physics, Institute of Physics and Astronomy, Faculty of Science, University of Potsdam, Potsdam, Germany Sebastian Raabe, Applied Condensed-Matter Physics, Institute of Physics and Astronomy, Faculty of Science, University of Potsdam, Potsdam, Germany Werner Wirges, Applied Condensed-Matter Physics, Institute of Physics and Astronomy, Faculty of Science, University of Potsdam, Potsdam, Germany Heitor Cury Basso, Department of Electrical Engineering, Engineering School of São Carlos, University of São Paulo, São Carlos, SP, Brazil Reimund Gerhard, Applied Condensed-Matter Physics, Institute of Physics and Astronomy, Faculty of Science, University of Potsdam, Potsdam, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The morphological manipulation, structural characterization, and optical properties of different CdSe nanocrystals were reported. Several different CdSe nanostructures, including nanowires, tetrapod crystals, and nanoparticles were grown by varying the volume ratio of triethylenetetraamine (TETA) and water (WA) in their mixed solution. By manipulating the growth driving force (i.e., the degree of supersaturation) and kinetics of the process (i.e., growth rate), the morphology and crystal structure of CdSe nanocrystals can be tailored. Growth driving force changed their morphology from nanowires to tetrapod structures and from the latter structure to nanoparticles. Moreover, kinetics of the process altered their crystal structure from wurtzite to zinc blende. The optical property of CdSe nanocrystals was investigated using UV-vis spectroscopy. The absorption edge of CdSe nanostructures showed a blue shift. CdSe nanocrystals prepared under optimized conditions showed good microstructural and optical properties for solar cell application. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6789-6 Authors M. R. Mohammadi, Department of Materials Science and Engineering, Sharif University of Technology, Azadi Street, Tehran, Iran V. Zarghami, Department of Materials Science and Engineering, Sharif University of Technology, Azadi Street, Tehran, Iran D. J. Fray, Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, UK Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Free-standing optoelectronic graphene–CdS–graphene oxide (G–CdS–GO) composite papers were prepared by vacuum-assisted self-assembly. G–CdS hybrids were first prepared by a hydrothermal method and GO acts as a dispersant which makes it easier to disperse them to form relatively stable aqueous suspensions for fabricating paper. Transmission electron microscopy shows that CdS quantum dots (QDs) with an average size of approximately 1–2 nm were distributed uniformly on the graphene sheets. Photoluminescence measurements for the as-prepared G–CdS–GO composite paper showed that the surface defect related emissions of attached CdS QDs decrease and blue shift obviously due to the change in particle size and the interaction of the surface of the CdS QDs with both the GO and the graphene sheets. The resulting paper holds great potential for applications in thin film solar cells, sensors, diodes, and so on. Content Type Journal Article Category Rapid communication Pages 1-6 DOI 10.1007/s00339-012-6774-0 Authors Yong-Feng Li, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 China Yan-Zhen Liu, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 China Wen-Zhong Shen, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 China Yong-Gang Yang, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 China Mao-Zhang Wang, Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 China Yue-Fang Wen, Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310058 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Ultra-thin anodic aluminum oxide membranes were prepared and served as deposition masks for fabrication of uniformly sized Ag nanodots with different aspect ratios on glass substrates. The surface plasmon resonance (SPR) properties of the supported Ag nanodots were investigated and compared with the predictions of the generalized Maxwell–Garnett theory. By modeling the nanodots as spheroids without adjusting their real geometrical parameters input to the calculation, the resulting theoretical SPR wavelengths are in good agreement with measured extinction peaks. The discrepancy between the theoretical and experimental plasmon resonance peak maxima is within 10 nm for the nanodots with an aspect ratio of less than 1.5. Although this wavelength discrepancy becomes large as the aspect ratio is increased, it is kept at approximately 35 nm for the nanodots with an aspect ratio of 2.44. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7404-6 Authors I-Chen Chen, Institute of Materials Science and Engineering, National Central University, Jhongli, 320 Taiwan Yen-Hsun Chen, Institute of Materials Science and Engineering, National Central University, Jhongli, 320 Taiwan Yu-Cian Wang, Institute of Materials Science and Engineering, National Central University, Jhongli, 320 Taiwan Meng-Hong Shih, Institute of Materials Science and Engineering, National Central University, Jhongli, 320 Taiwan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Superluminal transmission of electromagnetic waves is usually observed in a narrow bandwidth range and the velocity outside this range is subluminal. In this paper, it is shown that the transmission coefficient for superluminal propagation through a periodic metamaterial structure satisfies a sum rule. The sum rule and its corresponding physical bound relate frequency regions with a phase velocity above an arbitrary threshold with the thickness of the slab. The theoretical results are illustrated with numerical examples. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7407-3 Authors Mats Gustafsson, Department of Electrical and Information Technology, Lund University, Lund, Sweden Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Optical devices for the terahertz wave band are being developed now and require better designs. This paper proposes an artificial dielectric lens with metallic corrugated structures for the terahertz wave band. A periodic analysis model extracted from the full model by assuming periodicity confirms the phase delay, which produces the focusing effect. Full model analysis also confirms the focusing effect. The full model analysis also confirms that the focusing length is longer as the spacing of corrugated baffles is wider. The focusing length is longer the metallic groove width is wider. The focusing length is longer as the groove depth is shallower. The lens shape without grooves does not produce the focusing effect. The results of the full model analysis are qualitatively consistent with those of the periodic model ones. This implies that the design for an exact size lens is possible by using the periodic model. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7394-4 Authors Takuya Konno, Department of Electrical and Electronic Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan Takahiro Suzuki, Department of Electrical and Electronic Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan John C. Young, Electrical and Computer Engineering, University of Kentucky, Lexington, KY 40506-0046, USA Mikio Saigusa, Department of Electrical and Electronic Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan Keisuke Takano, Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan Hideaki Kitahara, Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan Masanori Hangyo, Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan Takehito Suzuki, Department of Electrical and Electronic Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Carbon nanotubes (CNTs) have been produced by the tunneling of cobalt nanoparticles in carbon fibers that are derived from electrospun polyacrylonitrile (PAN) fibers. During annealing, the PAN fibers transform to a composite of cobalt nanodroplets and carbon fibers. Driven by the high chemical potential of wrinkled graphene platelets and amorphous carbon with respect to graphite, the cobalt nanodroplets are to tunnel in the carbon fibers. When cobalt nanodroplets have an elongated shape, carbon atoms dissolved in the droplets precipitate preferentially and completely at their lateral sides, producing perfect CNTs that form bulk structures. Content Type Journal Article Category Rapid communication Pages 1-3 DOI 10.1007/s00339-012-7398-0 Authors J. L. Li, School of Materials Science and Chemical Engineering, Hainan University, Haikou, 570228 China H. T. Ye, School of Engineering and Applied Science, Aston University, Birmingham, B4 7ET UK Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We investigate terahertz plasmon–polariton (PP) resonances for hetero-structures (AlGaN/GaN, SiGe/Si/SiGe, AlGaAs/GaAs, and InAlN/GaN) with a grating coupler in order to find the overall optimal structure showing the strongest absorption for terahertz detection (THz). We show by a parametric study (influence of geometric dimensions, electron concentration, temperature, etc.) that refined and intense resonances can be obtained at specific frequency. GaN based heterostructures present the higher PP resonances at room temperature. The roles of the finite thicknesses of lossy metal grating and a two-dimensional gas (2DEG) layer on observed absorption are also investigated. Absorption spectra for three kinds of heterogeneous charge density profiles (piecewise, linear, and parabolic) of 2DEG was investigated and compared for an AlGaAs/GaAs structure because some physical parameters such as the Fermi level pinning at the interface semiconductor/air are well established only for this heterostructure. We show that the PP resonance (amplitude and frequency position) is modulated by the charge concentration but also by the metallization biasing. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7371-y Authors L. Cao, Institut d’Electronique Fondamentale, CNRS UMR 8622, Université Paris Sud, 91405 Orsay cedex, France A.-S. Grimault-Jacquin, Institut d’Electronique Fondamentale, CNRS UMR 8622, Université Paris Sud, 91405 Orsay cedex, France F. Aniel, Institut d’Electronique Fondamentale, CNRS UMR 8622, Université Paris Sud, 91405 Orsay cedex, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Dielectric elastomer actuators (DEAs) are flexible lightweight actuators that can generate strains of over 100 %. They are used in applications ranging from haptic feedback (mm-sized devices), to cm-scale soft robots, to meter-long blimps. DEAs consist of an electrode-elastomer-electrode stack, placed on a frame. Applying a voltage between the electrodes electrostatically compresses the elastomer, which deforms in-plane or out-of plane depending on design. Since the electrodes are bonded to the elastomer, they must reliably sustain repeated very large deformations while remaining conductive, and without significantly adding to the stiffness of the soft elastomer. The electrodes are required for electrostatic actuation, but also enable resistive and capacitive sensing of the strain, leading to self-sensing actuators. This review compares the different technologies used to make compliant electrodes for DEAs in terms of: impact on DEA device performance (speed, efficiency, maximum strain), manufacturability, miniaturization, the integration of self-sensing and self-switching, and compatibility with low-voltage operation. While graphite and carbon black have been the most widely used technique in research environments, alternative methods are emerging which combine compliance, conduction at over 100 % strain with better conductivity and/or ease of patternability, including microfabrication-based approaches for compliant metal thin-films, metal-polymer nano-composites, nanoparticle implantation, and reel-to-reel production of μm-scale patterned thin films on elastomers. Such electrodes are key to miniaturization, low-voltage operation, and widespread commercialization of DEAs. Content Type Journal Article Category Invited paper Pages 1-27 DOI 10.1007/s00339-012-7402-8 Authors Samuel Rosset, Ecole Polytechnique Fédérale de Lausanne (EPFL), Jaquet-Droz 1, 2002 Neuchâtel, Switzerland Herbert R. Shea, Ecole Polytechnique Fédérale de Lausanne (EPFL), Jaquet-Droz 1, 2002 Neuchâtel, Switzerland Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Compact plasmonic structures made of gold nanoparticles chains are inserted on silicon optical waveguides. We show that silicon-on-insulator waveguide TE mode energy can be almost totally transferred in a 5 gold nanoparticles plasmonic chain, and that this short chain can also behave as a waveguide. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7406-4 Authors M. Fevrier, Laboratoire IEF, UMR 8622, Univ. Paris-Sud, Orsay, 91405 France P. Gogol, Laboratoire IEF, UMR 8622, Univ. Paris-Sud, Orsay, 91405 France A. Aassime, Laboratoire IEF, UMR 8622, Univ. Paris-Sud, Orsay, 91405 France D. Bouville, Laboratoire IEF, UMR 8622, Univ. Paris-Sud, Orsay, 91405 France R. Megy, Laboratoire IEF, UMR 8622, Univ. Paris-Sud, Orsay, 91405 France B. Dagens, Laboratoire IEF, UMR 8622, Univ. Paris-Sud, Orsay, 91405 France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Novel concepts of nonlinear-optical (NLO) photonic metamaterials (MMs) are proposed. They concern with greatly enhanced coherent NLO energy exchange between ordinary and backward waves (BWs) through the frequency-conversion processes. Two different classes of materials which support BWs are considered: crystals that support optical phonons with negative group velocity and MMs with specially engineered spatial dispersion. The possibility to replace plasmonic NLO MMs enabling magnetic response at optical frequencies, which are very challenging to engineer, by the ordinary readily available crystals, are discussed. The possibility to mimic extraordinary NLO frequency-conversion propagation processes attributed to negative-index MMs (NIMs) is shown in some of such crystals, if optical phonons with negative group velocity and a proper phase-matching geometry are implemented. Here, optical phonons are used as one of the coupled counterparts instead of backward electromagnetic waves (BEMWs). The appearance of BEMWs in metaslabs made of carbon nanotubes, the possibilities and extraordinary properties of BW second harmonic generation in such MMs is another option of nonmagnetic NIMs, which is described too. Among the applications of the proposed photonic materials is the possibility of creation of a family of unique BW photonic devices such as frequency doubling metamirror and Raman amplifiers with greatly improved efficiency. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7390-8 Authors Alexander K. Popov, University of Wisconsin-Stevens Point, Stevens Point, WI 54481, USA Mikhail I. Shalaev, Siberian Federal University, 660041 Krasnoyarsk, Russian Federation Sergey A. Myslivets, Institute of Physics of Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation Vitaly V. Slabko, Siberian Federal University, 660041 Krasnoyarsk, Russian Federation Igor S. Nefedov, SMARAD Center of Excellence, Aalto University, 00076 Aalto, Finland Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We show that the metal nanoparticle chains supporting localized surface plasmon resonance can behave as transmission Bragg gratings on a dielectric waveguide. An analytical model is developed to interpret the experimental results. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7395-3 Authors M. Fevrier, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France P. Gogol, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France A. Aassime, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France R. Megy, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France D. Bouville, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France J. M. Lourtioz, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France B. Dagens, Laboratoire IEF, UMR 8622, Univ Paris-Sud, Orsay, 91405 France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Modeling of ion-implanted boron redistribution in silicon crystals during low-temperature annealing with a small thermal budget has been carried out. It was shown that formation of “tails” in the low-concentration region of impurity profiles occurs due to the long-range migration of boron interstitials. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7378-4 Authors O. I. Velichko, Department of Physics, Belorussian State University of Informatics and Radioelectronics, 6, P. Brovki Street, Minsk, 220013 Belarus A. P. Kavaliova, Department of Physics, Belorussian State University of Informatics and Radioelectronics, 6, P. Brovki Street, Minsk, 220013 Belarus Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We have designed a flat graded index lens made from a metallic graded 2D photonic crystal. The gradient of index has been obtained by varying the filling factor of a flat slab of photonic crystal in the direction perpendicular to that of the propagation of the electromagnetic field. This gradient has been designed in such a way that the flat slab focuses a plane wave. With applications in the microwave range in view, we considered a photonic crystal which consists of copper strips. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7386-4 Authors Fabian Gaufillet, Institut d’Électronique Fondamentale, UMR8622, Université Paris-Sud, Orsay, 91405 France Éric Akmansoy, Institut d’Électronique Fondamentale, UMR8622, Université Paris-Sud, Orsay, 91405 France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    This paper presents a method to improve the circular polarization of an Archimedean spiral antenna placed over a radial Artificial Magnetic Conductor (AMC). Results have been compared with the same radiating element over a more classical AMC reflector. A prototype of an Archimedean two-wire spiral antenna has been built to operate from 0.5 GHz to 6 GHz. Measurement results with this radial AMC give a relative bandwidth of 79 %, in which the broadside RHCP gain is improved. In this bandwidth the axial ratio of Archimedean spiral antenna placed over a radial AMC is less than 2 dB whereas it is higher than 3 dB with a classical cartesian shape of AMC reflector. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7401-9 Authors M. Grelier, Institut Mines-Telecom, Telecom ParisTech—LTCI CNRS UMR 5141, 46 rue Barrault, 75634 Paris Cedex 13, France C. Djoma, Institut Mines-Telecom, Telecom ParisTech—LTCI CNRS UMR 5141, 46 rue Barrault, 75634 Paris Cedex 13, France M. Jousset, Thales Systèmes Aéroportés, 10 avenue de la 1ère DFL, 29238 Brest Cedex 3, France S. Mallégol, Thales Systèmes Aéroportés, 10 avenue de la 1ère DFL, 29238 Brest Cedex 3, France A. C. Lepage, Institut Mines-Telecom, Telecom ParisTech—LTCI CNRS UMR 5141, 46 rue Barrault, 75634 Paris Cedex 13, France X. Begaud, Institut Mines-Telecom, Telecom ParisTech—LTCI CNRS UMR 5141, 46 rue Barrault, 75634 Paris Cedex 13, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    In this paper we study the electro-optical behavior and the application of indium–tin oxide (ITO) and aluminum-doped zinc oxide (AZO) bilayer thin films for silicon solar cells. ITO–AZO bilayer thin films were deposited on glass substrates using radio-frequency magnetron sputtering. The experimental results show that a decrease in the electrical resistivity of the ITO–AZO bilayer thin films has been achieved without significant degradation of optical properties. In the best case the resistivity of the bilayer films reached a minimum of 5.075×10 −4  Ω cm when the thickness of the AZO buffer layer was 12 nm. The ITO–AZO bilayer films were applied as the front electrodes of amorphous silicon solar cells and the short-circuit current density of the solar cells was considerably increased. Content Type Journal Article Category Rapid communication Pages 1-5 DOI 10.1007/s00339-012-7431-3 Authors Chao Wang, Henan Key Laboratory of Photovoltaic Materials, School of Physics and Electronics, Henan University, Kaifeng, 475004 P.R. China Yanli Mao, Henan Key Laboratory of Photovoltaic Materials, School of Physics and Electronics, Henan University, Kaifeng, 475004 P.R. China Xiangbo Zeng, Key Laboratory of Semiconductor Materials, Chinese Academy of Sciences, Beijing, 100083 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    In this paper, the effect of coupling two kinds of metamaterial cells with a coil to achieve Magnetic Resonance Imaging (MRI) is investigated. Both an array of four spirals then a single spiral-shaped metamaterial are put on the top of the coil antenna. These metamaterial based resonant structures are designed to work at 63 MHz. They are intended to increase the sensitivity of the whole system and to improve the homogeneity of the RF magnetic field pattern. The spiral-shaped metamaterials added on the top of the antenna gave very promising numerical results. The calculated magnetic fields are homogeneous and their magnitudes are multiplied by factor of 4 up to 6. We are fabricating both structures using microfabrication techniques because of the small size of the structures. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7408-2 Authors M. S. Khennouche, IEF, University of Paris Sud, 91405 Orsay cedex, France F. Gadot, IEF, University of Paris Sud, 91405 Orsay cedex, France B. Belier, IEF, University of Paris Sud, 91405 Orsay cedex, France A. de Lustrac, IEF, University of Paris Sud, 91405 Orsay cedex, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Formation of periodic subwavelength ripples on a metallic tungsten surface is investigated through a line-scribing method under the irradiation of 800 nm, 50 fs to 8 ps ultra-short laser pulses. The distinctive features of the induced ripple structures are described in detail with different laser parameters. Experimental measurements reveal that with gradual decrease of the laser fluence, the pulse duration or the scanning speed, the ripple period is inclined to reduce but the ripple depth tends to become pronounced. Theoretical analyses suggest that the transient dielectric function change of the tungsten surface mainly originates from the nonequilibrium distribution of electrons due to the d -band transitions. A sandwich-like physical model of air–plasma–target is proposed and the excitation of a surface plasmon polaritonic (SPP) wave is supposed to occur on the interface between the metallic target and the electron plasma layer. Formation of ripples can be eventually attributed to the laser–SPP interference. Theoretical interpretations are consistent with the experimental observations. Content Type Journal Article Pages 1-9 DOI 10.1007/s00339-012-7261-3 Authors Lu Xue, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Institute of Modern Optics, Nankai University, Tianjin, 300071 China Jianjun Yang, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Institute of Modern Optics, Nankai University, Tianjin, 300071 China Yang Yang, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Institute of Modern Optics, Nankai University, Tianjin, 300071 China Yishan Wang, State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Science, Xi’an, Shaanxi 710119, China Xiaonong Zhu, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Institute of Modern Optics, Nankai University, Tianjin, 300071 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    A composite of graphene (GE) supported by rod-like Fe 3 O 4 nanocrystals has been fabricated by a simple one-step chemical route. X-ray diffraction and transmission electron microscopy results show that the Fe 3 O 4 nanorods with diameters in the range of 15–20 nm and lengths of 150–200 nm were firmly assembled on the GE nanosheet surface. Magnetic property investigation indicated that the Fe 3 O 4 /GE composites exhibit a ferromagnetic behavior and possess a saturation magnetization of 50.11 emu g −1 . Moreover, Fe 3 O 4 /GE composites showed a very high adsorption capacity of Congo red. Content Type Journal Article Category Rapid communication Pages 1-5 DOI 10.1007/s00339-012-7278-7 Authors Xiao-hua Jia, School of the Environment, Jiangsu University, Zhenjiang, Jiangsu 212013, China Hao-Jie Song, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China Chun-ying Min, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China Xue-Qiang Zhang, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    A contact transient electrothermal technique (CTET) is developed to characterize the thermal transport between one-dimensional conductive and nonconductive microscale wires that are in point contact. This technique is a significant advance from the transient electrothermal method that is used to characterize the thermophysical properties of individual one-dimensional micro-wires. A steady-state analytical solution and a transient numerical solution are used to independently determine the value for the thermal contact resistance between the wires at the contact point. The CTET technique is applied to measurement of the thermal contact resistance between crossed Pt wires (25.4 μm diameter) and the thermal contact resistance between a glass fiber (8.9 μm diameter) in contact with a Pt wire (25.4 μm diameter). For Pt wire contact, the thermal contact resistance increases from 8.94×10 4 to 7.05×10 5  K/W when the heating current changes from 20 to 50 mA. For the Pt/glass fiber contact, the thermal contact resistance is much larger (2.83×10 6  K/W), mainly due to the smaller area at the contact point. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7177-y Authors Nathan Van Velson, Department of Mechanical Engineering, Iowa State University, 2010 Black Engineering Building, Ames, IA 50011, USA Xinwei Wang, Department of Mechanical Engineering, Iowa State University, 2010 Black Engineering Building, Ames, IA 50011, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Optical conductivity of a zigzag carbon nanotube is investigated in the context of the Holstein model. Green’s function approach is applied to calculate the optical conductivity as a function of photon frequency, temperature, and electron–phonon coupling strength. Based on our results, optical conductivity decreases with electron–phonon coupling constant for both metallic and semiconducting carbon nanotubes. Our results show that temperature yields shortening the height of peaks of zigzag CNT optical absorption. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7178-x Authors Hamed Rezania, Department of Physics, Razi University, Kermanshah, Iran Farid Taherkhani, Department of Chemistry, Razi University, Kermanshah, Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The dielectric constant is an essential electrical parameter to the achievable voltage-induced deformation of the dielectric elastomer. This paper primarily focuses on the temperature dependence of the dielectric constant (within the range of 173 K to 373 K) for the most widely used acrylic dielectric elastomer (VHB 4910). First the dielectric constant was investigated experimentally with the broadband dielectric spectrometer (BDS). Results showed that the dielectric constant first increased with temperature up to a peak value and then dropped to a relative small value. Then by analyzing the fitted curves, the Cole–Cole dispersion equation was found better to characterize the rising process before the peak values than the Debye dispersion equation, while the decrease process afterward can be well described by the simple Debye model. Finally, a mathematical model of dielectric constant of VHB 4910 was obtained from the fitted results which can be used to further probe the electromechanical stability of the dielectric elastomers. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7254-2 Authors Junjie Sheng, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 China Hualing Chen, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 China Bo Li, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 China Longfei Chang, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, 710049 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Mn-doped ZnO nanowires have been fabricated through a high temperature vapor-solid deposition process. The low-temperature photoluminescence spectra of the samples show that there are multipeak emissions at the ultraviolet (UV) region (about 3.4–3.0 eV). The excitonic and phonon-assisted transitions in Mn-doped ZnO nanowires were investigated. The results show that there is an obvious oscillatory structure emission at the UV region under low temperature from 12–125 K. The oscillatory structure has an energy periodicity about 70 meV and the oscillatory structure is mainly attributed to longitudinal optical (LO) phonon replicas of free excitons (FX). The multipeak emissions at 12 K are attributed to a donor-bound exciton (DBX, 3.3617 eV), 1LO-phonon replicas of a free exciton (FX-1LO, 3.3105 eV), 2LO-phonon replicas of a free exciton (FX-2LO, 3.2396 eV), and 3LO-phonon replicas of a free exciton (FX-3LO, 3.1692 eV), respectively. The intensity of UV emission and the efficiency of emission from the Mn-doped ZnO nanowires are improved. Content Type Journal Article Category Rapid communication Pages 1-5 DOI 10.1007/s00339-012-7294-7 Authors Jun Zhang, Key Laboratory of Optoelectronic Information Techniques of Shandong, Institute Optoelectronic Information Science &Techniques, Yantai University, Yantai, 264005 P.R. China Feihong Jiang, Key Laboratory of Optoelectronic Information Techniques of Shandong, Institute Optoelectronic Information Science &Techniques, Yantai University, Yantai, 264005 P.R. China Shuanghong Ding, Key Laboratory of Optoelectronic Information Techniques of Shandong, Institute Optoelectronic Information Science &Techniques, Yantai University, Yantai, 264005 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Powdered layered double hydroxides (LDHs)—also known as hydrotalcite-like (HT)—compounds have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic or organic molecules. Assembling thin films of nano-sized LDHs onto flat solid substrates is an expanding area of research, with promising applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. The exploitation of LDHs as vehicles to carry dispersed metal nanoparticles onto a substrate is a new approach to obtain composite thin films with prospects for biomedical and optical applications. We report the deposition of thin films of Ag nanoparticles embedded in a Mg–Al layered double hydroxide matrix by pulsed laser deposition (PLD). The Ag-LDH powder was prepared by co-precipitation at supersaturation and pH = 10 using aqueous solutions of Mg and Al nitrates, Na hydroxide and carbonate, and AgNO 3 , having atomic ratios of Mg/Al = 3 and Ag/Al = 0.55. The target to be used in laser ablation experiments was a dry pressed pellet obtained from the prepared Ag-LDH powder. Three different wavelengths of a Nd:YAG laser (266, 532 and 1064 nm) working at a repetition rate of 10 Hz were used. X-Ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and secondary ions mass spectrometry (SIMS) were used to investigate the structure, surface morphology and composition of the deposited films. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7162-5 Authors A. Matei, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania R. Birjega, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania A. Vlad, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania C. Luculescu, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania G. Epurescu, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania F. Stokker-Cheregi, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania M. Dinescu, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele, Romania R. Zavoianu, Faculty of Chemistry, Department of Chemical Technology and Catalysis, University of Bucharest, 4-12 Regina Elisabeta Bd., Bucharest, Romania O. D. Pavel, Faculty of Chemistry, Department of Chemical Technology and Catalysis, University of Bucharest, 4-12 Regina Elisabeta Bd., Bucharest, Romania Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The possibility of printing two-dimensional micropatterns of biomolecule solutions is of great interest in many fields of research in biomedicine, from cell-growth and development studies to the investigation of the mechanisms of communication between cells. Although laser-induced forward transfer (LIFT) has been extensively used to print micrometric droplets of biological solutions, the fabrication of complex patterns depends on the feasibility of the technique to print micron-sized lines of aqueous solutions. In this study we investigate such a possibility through the analysis of the influence of droplet spacing of a water and glycerol solution on the morphology of the features printed by LIFT. We prove that it is indeed possible to print long and uniform continuous lines by controlling the overlap between adjacent droplets. We show how, depending on droplet spacing, several printed morphologies are generated, and we offer, in addition, a simple explanation of the observed behavior based on the jetting dynamics characteristic of the LIFT of liquids. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7279-6 Authors A. Palla-Papavlu, Departament de Física Aplicada i Optica, Universitat de Barcelona (UB), Martí i Franquès 1, 08028 Barcelona, Spain C. Córdoba, Departament de Física Aplicada i Optica, Universitat de Barcelona (UB), Martí i Franquès 1, 08028 Barcelona, Spain A. Patrascioiu, Departament de Física Aplicada i Optica, Universitat de Barcelona (UB), Martí i Franquès 1, 08028 Barcelona, Spain J. M. Fernández-Pradas, Departament de Física Aplicada i Optica, Universitat de Barcelona (UB), Martí i Franquès 1, 08028 Barcelona, Spain J. L. Morenza, Departament de Física Aplicada i Optica, Universitat de Barcelona (UB), Martí i Franquès 1, 08028 Barcelona, Spain P. Serra, Departament de Física Aplicada i Optica, Universitat de Barcelona (UB), Martí i Franquès 1, 08028 Barcelona, Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Based on local density approximation and Hubbard-U corrections (LDA+U), we study the influence of Coulomb interaction for Tb 4f states on the optical properties of the recently discovered superconductor, such as TbOFeAs. Within the incorporation of onsite Hubbard effect in TbOFeAs, we discuss the electronic structure, as well as the optical spectra and we compared them to LDA calculations. For non-magnetic (NM) configuration, the electronic structure exhibits high density of states, N ( E F ) in the proximity of Fermi level. With and without the electronic correlation effects, we carried out the calculations for the optical properties such as the optical conductivity, joint density of states (JDOS), optical absorption, the electron energy loss function and reflectivity of TbOFeAs in a large photon energy scale of 30 eV. Despite the absence of a Mott insulator transition, we infer that the electronic correlation effects are prominent in the recently discovered superconductor, like TbOFeAs. We also predict the in-plane anisotropy of plasma frequency that has been evaluated recently in the other ReOFeAs systems. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7286-7 Authors A. Laref, Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11145 King Saudi Arabia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    While the emergence of pottery manufacturing is a wide-spread historical occurrence, and one that has garnered the attention of archaeologists for decades, we know very little about how these ancient vessels were created. Through the application of radiographic scanning and computed tomography this paper provides insights into the manufacturing techniques used by the earliest potters in North America. While x-rays have been used to investigate ceramic manufacturing techniques for decades, this paper provides a reassessment of radiography in light of advances in both computed tomography and reconstructive software. Content Type Journal Article Pages 1-11 DOI 10.1007/s00339-012-7287-6 Authors Matthew Sanger, The American Museum of Natural History, New York, NY, USA James Thostenson, The American Museum of Natural History, New York, NY, USA Morgan Hill, The American Museum of Natural History, New York, NY, USA Hannah Cain, Columbia University, New York, NY, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    A thorough microscopic investigation by SR XRF and micro-PIXE brings insight into the probable techniques used in the manufacture of thirteen Dacian gold bracelets, one of the most spectacular archaeological finds ever on the territory of Romania. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7306-7 Authors Bogdan Constantinescu, Horia Hulubei National Institute of Physics and Nuclear Engineering Bucharest, str. Atomiştilor 407, Măgurele, Ilfov 077125, Romania Angela Vasilescu, Horia Hulubei National Institute of Physics and Nuclear Engineering Bucharest, str. Atomiştilor 407, Măgurele, Ilfov 077125, Romania Martin Radtke, Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter Strasse 11, 12489 Berlin, Germany Uwe Reinholz, Laboratoire du Centre de Recherche et de Restauration des Musées de France, Palais du Louvre (CNRS-LC2RMF UMR 171), 14 Quai F. Mitterand, 75001 Paris, France Claire Pacheco, Laboratoire du Centre de Recherche et de Restauration des Musées de France, Palais du Louvre (CNRS-LC2RMF UMR 171), 14 Quai F. Mitterand, 75001 Paris, France Laurent Pichon, Laboratoire du Centre de Recherche et de Restauration des Musées de France, Palais du Louvre (CNRS-LC2RMF UMR 171), 14 Quai F. Mitterand, 75001 Paris, France Ernest Oberländer-Târnoveanu, National History Museum of Romania (MNIR), calea Victoriei 12, Bucharest, sector 3, 030026 Romania Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description: Erratum to: Direct laser printing of thin-film polyaniline devices Content Type Journal Article Category Erratum Pages 1-1 DOI 10.1007/s00339-012-7307-6 Authors M. Kandyla, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece C. Pandis, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece S. Chatzandroulis, Institute of Microelectronics, NCSR Demokritos, Agia Paraksevi, Athens, 15310 Greece P. Pissis, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece I. Zergioti, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    A facile, green method was explored for the organic-inorganic complex coating with superhydrophobic and transparent property on glass matrix. The glass surface was firstly treated with polyethylene glycol (PEG) and SiO 2 organic-inorganic solution and then modified with a layer of 1,1,1,3,3,3-Hexamethyldisilazane (HMDS). The glass samples were characterized by scanning electron microscopy (SEM), water contact angle (CA) measurement, and UV–Vis spectrophotometry. The results showed that the optical transmission over the visible range up to 89 % (in reference to 100 % transmission defined by bare glass substrate), and the water CA of the film reached 168 ∘ . Superhydrophobic coatings with excellent optical transmittance will have potential applications in our daily life. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7176-z Authors Ye Zhang, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Jialin Li, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Fangzhi Huang, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Shikuo Li, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Yuhua Shen, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Anjian Xie, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Wei Duan, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Fang Wang, School of Chemistry and Chemical Engineering, Anhui University, Hefei, 230039 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The corrosion of iron-based archaeomaterials in anoxic environments leads mainly to Fe(II) compounds, like the hydroxychloride β -Fe 2 (OH) 3 Cl, chukanovite Fe 2 (OH) 2 CO 3 or siderite FeCO 3 . The understanding of the mechanisms then necessarily implies a thorough investigation of the chemical, mechanical and morphological characteristics of the Fe(II)-based layer that develops between the metal surface and the environment. In the peculiar case of Fe(II) compounds, generally very reactive towards O 2 , the main concern is to prevent any transformation by air during the analysis. The EBSD technique is adapted on a scanning electron microscope (SEM) where the samples are analysed under vacuum and consequently sheltered from air. Different options offered by EBSD for phase characterisation and microstructural study were tested for the first time on the rust layers of two archaeological iron nails. Results were confronted to those obtained by micro-Raman spectroscopy, which was used as reference method. Magnetite, Fe(II) hydroxychloride β -Fe 2 (OH) 3 Cl and siderite were analysed successfully but improvements have to be brought for the study of other compounds such as iron oxyhydroxides and chukanovite. The choice of experimental parameters in our approach as well as the potentialities and limits of the technique for this kind of application are discussed. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7174-1 Authors Ilanith Azoulay, Laboratoire des Sciences de l’Ingénieur pour l’Environnement, FRE 3474 CNRS—Université de La Rochelle, Bât. Marie Curie, Avenue Michel Crépeau, 17042 La Rochelle cedex 01, France Egle Conforto, Laboratoire des Sciences de l’Ingénieur pour l’Environnement, FRE 3474 CNRS—Université de La Rochelle, Bât. Marie Curie, Avenue Michel Crépeau, 17042 La Rochelle cedex 01, France Philippe Refait, Laboratoire des Sciences de l’Ingénieur pour l’Environnement, FRE 3474 CNRS—Université de La Rochelle, Bât. Marie Curie, Avenue Michel Crépeau, 17042 La Rochelle cedex 01, France Céline Rémazeilles, Laboratoire des Sciences de l’Ingénieur pour l’Environnement, FRE 3474 CNRS—Université de La Rochelle, Bât. Marie Curie, Avenue Michel Crépeau, 17042 La Rochelle cedex 01, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We have analyzed the ablation depth yield of fused silica irradiated with shaped pulse trains with a separation of 500 fs and increasing or decreasing intensity envelopes. This temporal separation value is extracted from previous studies on ablation dynamics upon irradiation with transform-limited 100 fs laser pulses. The use of decreasing intensity pulse trains leads to a strong increase of the induced ablation depth when compared to the behavior, at the same pulse fluence, of intensity increasing pulse trains. In addition, we have studied the material response under stretched (500 fs, FWHM) and transform-limited (100 fs, FWHM) pulses, for which avalanche or multiphoton ionization respectively dominates the carrier generation process. The comparison of the corresponding evolution of the ablated depth vs. fluence suggests that the use of pulse trains with decreasing intensity at high fluences should lead to enhanced single exposure ablation depths, beyond the limits corresponding to MPI- or AI-alone dominated processes. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7238-2 Authors J. Hernandez-Rueda, Laser Processing Group, Instituto de Óptica, C.S.I.C., Serrano 121, 28006 Madrid, Spain J. Siegel, Laser Processing Group, Instituto de Óptica, C.S.I.C., Serrano 121, 28006 Madrid, Spain D. Puerto, Laser Processing Group, Instituto de Óptica, C.S.I.C., Serrano 121, 28006 Madrid, Spain M. Galvan-Sosa, Laser Processing Group, Instituto de Óptica, C.S.I.C., Serrano 121, 28006 Madrid, Spain W. Gawelda, Laser Processing Group, Instituto de Óptica, C.S.I.C., Serrano 121, 28006 Madrid, Spain J. Solis, Laser Processing Group, Instituto de Óptica, C.S.I.C., Serrano 121, 28006 Madrid, Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Structurally tuned multiferroic state is demonstrated for BiFeO 3 -based compounds. The electric and magnetic orders are strongly affected by the coexistence of R3c and Cm phases, i.e., by structural softness through monoclinicity, which leads the multiferroism to be driven by the same cation. The Cm phase enhances the ferroelectric and magnetic responses through Bi/Ba–O and Fe/Ti–O bonds by influencing structural distortions and ion valence. We also show the strong correlations between ferroic orders, structural arrangements, and tuning of the ion valence in the perovskite B site. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7258-y Authors R. A. M. Gotardo, Departamento de Física, Universidade Estadual de Maringá, Av. Colombo, 5790, Maringá, Paraná 87020-900, Brazil L. F. Cótica, Departamento de Física, Universidade Estadual de Maringá, Av. Colombo, 5790, Maringá, Paraná 87020-900, Brazil I. A. Santos, Departamento de Física, Universidade Estadual de Maringá, Av. Colombo, 5790, Maringá, Paraná 87020-900, Brazil M. Olzon-Dyonisio, Departamento de Física, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, São Carlos, São Paulo 13565-345, Brazil S. D. Souza, Departamento de Física, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, São Carlos, São Paulo 13565-345, Brazil D. Garcia, Departamento de Física, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, São Carlos, São Paulo 13565-345, Brazil J. A. Eiras, Departamento de Física, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, São Carlos, São Paulo 13565-345, Brazil A. A. Coelho, Departamento de Física Aplicada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Barão Geraldo, Campinas, São Paulo 13083-970, Brazil Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We have investigated the magnetization structure and magnetization curves of individual rectangularity shaped permalloy particles using scanning X-ray microscopy in the ultrasoft X-ray regime. Magnetic contrast originates from X-ray magnetic circular dichroism and from the transverse magnetooptical Kerr effect. We studied magnetization curves in dependence on the field direction for particles of different shapes and sizes. Adjacent particles cause a significant dipole interaction. Asymmetric magnetization loops indicate the presence of non-linear magnetooptical effects. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7257-z Authors S. A. Nepijko, Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz, Germany O. V. Pylypenko, Sumy State University, Rimsky-Korsakov Str. 2, 40007 Sumy, C.I.S., Ukraine L. V. Odnodvorets, Sumy State University, Rimsky-Korsakov Str. 2, 40007 Sumy, C.I.S., Ukraine E. Kisker, Institute of Applied Physics, University of Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany H. J. Elmers, Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz, Germany G. Schönhense, Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    A series of [Fe 65 Co 35 –O/SiO 2 ] n multilayer thin films with different SiO 2 separate layer thicknesses ( t =0–3 nm) and fixed Fe 65 Co 35 –O layer thickness (5.4 nm) have been fabricated on (100) silicon and glass substrates by reactive magnetron co-sputtering. Microstructure analysis and magnetic measurement results show that Fe 65 Co 35 –O grain size and magnetic properties can be adjusted by varying the thickness of SiO 2 layers. All films reveal an evident in-plane uniaxial magnetic anisotropy (IPUMA) when the thickness of SiO 2 monolayer changes from t =0 to 3 nm. The hard axis coercivity ( H ch ) reveals a minimum of 9 Oe at t =1 nm while the easy axis coercivity ( H ce ) exhibits a minimum of 16 Oe at t =2 nm. For t =1 nm and 2 nm, the IPUMA fields ( H k ) are 95 and 207 Oe, the saturation magnetizations ( M s ) are 1.8 and 1.6 T, the real part of the complex permeabilities (below 3.0 GHz) are more than 217 and 104, and the ferromagnetic resonance frequencies ( f r ) are 3.6 and 5.2 GHz, respectively. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7259-x Authors Y. Wang, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005 P.R. China H. Geng, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005 P.R. China J. B. Wang, Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, 730000 P.R. China S. Nie, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005 P.R. China L. S. Wang, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005 P.R. China Y. Chen, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005 P.R. China D. L. Peng, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen, 361005 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Transformation acoustics is employed to design an acoustic bending waveguide. A two-dimensional square area with anisotropic and homogeneous material properties is transformed into a fan-shaped area with anisotropic and inhomogeneous material properties to rotate the direction of beam propagation. An alternating layered structure is considered to approximate a medium with anisotropic material properties. From the calculation results, the transformation medium can be realized by an alternating layered structure consisting of water and fluid with negative mass density. We propose that an acoustic metamaterial composed of three layers in water background can be designed to replace negative mass density fluid. The effective mass density and bulk modulus of the system that is composed of the acoustic metamaterial and water are dependent on the incident frequency and the geometric size of the acoustic metamaterial. We tune the geometric size of the acoustic metamaterial to approach the corresponding mass density distribution of the negative mass density fluid at a specific frequency. Thereby, the acoustic bending waveguide designed by using transformation acoustics can be achieved by the acoustic metamaterials. Content Type Journal Article Pages 1-11 DOI 10.1007/s00339-012-7296-5 Authors Liang-Yu Wu, Department of Mechanical Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, 70101 Taiwan Tzeh-Yi Chiang, Department of Mechanical Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, 70101 Taiwan Chia-Nien Tsai, Department of Mechanical Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, 70101 Taiwan Mei-Ling Wu, Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, 70 Lien-Hai Road, Kaohsiung, 80424 Taiwan Lien-Wen Chen, Department of Mechanical Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, 70101 Taiwan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The eutectic alloy of BiInSn was ablated in water by UV pulsed radiation. Electron microscopy of the ablated material shows spherical particles that fall into three size regimes: those with diameters of ∼0.5 μm, crystalline and amorphous particles with dimensions of ∼30 nm, and amorphous particles that are approximately 1 nm across. The 30-nm amorphous particles are homogeneous, while there are two types of 30-nm crystalline particles, those that separate into three phases and those that are homogeneous. The existence of different characteristic sizes is explained by two mechanisms: phase explosion and Rayleigh instability of the ejected melt. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7244-4 Authors O. R. Musaev, Department of Physics and Astronomy, University of Missouri Kansas City, 5100 Rockhill Rd., Kansas City, MO 64110, USA E. Sutter, Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA J. M. Wrobel, Department of Physics and Astronomy, University of Missouri Kansas City, 5100 Rockhill Rd., Kansas City, MO 64110, USA M. B. Kruger, Department of Physics and Astronomy, University of Missouri Kansas City, 5100 Rockhill Rd., Kansas City, MO 64110, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We report the evidence of a core–shell structure in the antiferromagnetic La 0.2 Ce 0.8 CrO 3 nanoparticles by using a combination of neutron diffraction, polarized neutron small angle scattering (SANSPOL), and dc magnetization techniques. The neutron diffraction study establishes that the present nanoparticles are antiferromagnetic in nature. The magnetic scattering in the SANSPOL study arises from the shell part of the nanoparticles due to the disordered surface spins. The analysis of the SANSPOL data shows that these nanoparticles have a mean core diameter of 12.3±1.1 nm, and a shell thickness of 2.8±0.4 nm, giving a core–shell structure with an antiferromagnetic core, and a shell with a net magnetic moment under an applied magnetic field. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7262-2 Authors P. K. Manna, Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 India S. M. Yusuf, Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 India M. D. Mukadam, Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 India J. Kohlbrecher, Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Epitaxial (Co,Fe) nitride films were prepared on TiN buffered Si(001) substrates by dual-target reactive co-sputtering method. With lower Co content, thin films mainly consist of (Co x Fe 1− x ) 4 N phase. With higher Co content, STEM EELS found no N signal in the thin film, and, combined with XRD results, shows that fcc Co is the main phase of the thin films instead of Co 4 N. The N 2 atmosphere is helpful to induce the fcc Co phase formation during dual-target reactive co-sputtering deposition. For the films with less Co content, the RT magnetization measurements show similar magnetic properties as epitaxial Fe 4 N(001) films, while increasing the Co content, the resulting fcc Co thin films show biaxial anisotropy with the [110] in-plane easy axis. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7251-5 Authors H. Xiang, Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA F.-Y. Shi, Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA M. S. Rzchowski, Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA P. M. Voyles, Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA Y. A. Chang, Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The photo-thermal deflection technique (PTD) is used to study the transport properties such as non-radiative lifetime of minority carriers ( τ nr ), electronic diffusivity ( D ) and surface recombination velocity ( S ) in bulk silicon (Si) and gallium antimonide (GaSb) semiconductors. A generalized one-dimensional theoretical model has been also developed, and the coincidence between experimental curves giving the normalized amplitude and phase variations versus square root modulation frequency and the corresponding theoretical curves makes possible to deduce the electronic parameters cited above. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7242-6 Authors S. Ilahi, Unité de Recherche de Caractérisation Photo-thermique et Modélisation, Institut Préparatoire aux Etudes d’Ingénieurs de Nabeul (IPEIN), Université de Carthage, Merazka, Nabeul, 8000 Tunisie F. Saadalah, Unité de Recherche de Caractérisation Photo-thermique et Modélisation, Institut Préparatoire aux Etudes d’Ingénieurs de Nabeul (IPEIN), Université de Carthage, Merazka, Nabeul, 8000 Tunisie N. Yacoubi, Unité de Recherche de Caractérisation Photo-thermique et Modélisation, Institut Préparatoire aux Etudes d’Ingénieurs de Nabeul (IPEIN), Université de Carthage, Merazka, Nabeul, 8000 Tunisie Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The magnetic properties of polycrystalline Yb 1− x Pr x FeO 3 (0≤ x ≤0.9) are systematically investigated. A cusp in the zero-field-cooled dc magnetization and a frequency-dependent peak in the ac susceptibility reveal the glassy behaviors in this system. Interestingly, for YbFeO 3 , the freezing temperature T f is just in the narrow spin-reorientation region of single-crystal YbFeO 3 reported previously. The frequency-dependent peak in the real part of the ac susceptibility can be described by critical slowing down of spin dynamics. The fit to this critical slowing down law yields the values τ 0 =2.79×10 −7  s and zv =2.61. The value of τ 0 is in good agreement with values found in cluster-glass systems. Anomalous thermal hysteresis in the field-cooled magnetization is found in all samples, with a crossover point between the field-cooled cooling and field-cooled warming curves. These anomalous thermal hysteresis behaviors are explained by the competing interaction between the iron-ion subsystem and rare-earth-ion subsystem. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7221-y Authors Shujuan Yuan, Department of Physics, Shanghai University, Shanghai, 200444 China Fenfen Chang, Department of Physics, Shanghai University, Shanghai, 200444 China Yiming Cao, Department of Physics, Shanghai University, Shanghai, 200444 China Xinyan Wang, Department of Physics, Shanghai University, Shanghai, 200444 China Baojuan Kang, Department of Physics, Shanghai University, Shanghai, 200444 China Jincang Zhang, Department of Physics, Shanghai University, Shanghai, 200444 China Shixun Cao, Department of Physics, Shanghai University, Shanghai, 200444 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Femtosecond laser material processing as micromachining and nanoparticles fabrication require a careful control of the fluences deposited on the samples. In many cases, best results are obtained by using fluences slightly above the Laser Ablation Threshold (LAT), therefore its accurate determination is an important requirement. LAT can be obtained by measuring the intensity of the acoustic signal generated during the ablation process as a function of the laser fluence. In this work femtosecond laser ablation thresholds of commercially polished stainless steel plates, white high impact polystyrene, frosted glass, antique rag papers and silicon oxynitride thin films were determined by using laser ablation induced photoacoustics (LAIP). Results were compared with similar data previously obtained by using a nanosecond Nd:YAG laser. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7230-x Authors Daniel J. O. Orzi, Centro de Investigaciones Ópticas, CONICET La Plata-CIC, CC 3, CP 1897 Gonnet, Buenos Aires, Argentina Fernando C. Alvira, Centro de Investigaciones Ópticas, CONICET La Plata-CIC, CC 3, CP 1897 Gonnet, Buenos Aires, Argentina Gabriel M. Bilmes, Centro de Investigaciones Ópticas, CONICET La Plata-CIC, CC 3, CP 1897 Gonnet, Buenos Aires, Argentina Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    In this paper, we prepared TiO 2 nanostructures by a hydrothermal method and investigated the influence of the ion and the effect of long alkyl chains of sodium dodecyl sulfate on the crystal phases of TiO 2 by experiments and theoretical calculations. The results indicate that the absorption of the H+HSO 4 fragment on rutile (110) is more stable than that of the 2H+SO 4 fragment and more favorable to the formation of anatase. The absorption and steric effects of sodium dodecyl sulfate on the surfaces of TiO 2 grains also have an important influence on the formation of mixed crystals by changing the speed and the way of octahedral TiO 6 units combining. Based on the above facts, we revised the original reaction scheme for crystalline titania formation by previous authors. Content Type Journal Article Category Rapid communication Pages 1-6 DOI 10.1007/s00339-012-7265-z Authors Chaohong Liu, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100 P.R. China Xin Wang, Institute of Material Science and Engineering, Ocean University of China, Qingdao, 266100 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Electrospinning is a simple and versatile fiber synthesis technique in which a high-voltage electric field is applied to a stream of polymer melt or polymer solution, resulting in the formation of continuous micro/nanofibers. Halloysite nanotubes (HNT) have been found to achieve improved structural and mechanical properties when embedded into various polymer matrices. This research work focuses on blending poly( ε -caprolactone) (PCL) (9 and 15 wt%/v) and poly(lactic acid) (PLA) (fixed at 8 wt%/v) solutions with HNT at two different concentrations 1 and 2 wt%/v. Both unmodified HNT and HNT modified with 3-aminopropyltriethoxysilane (ASP) were utilized in this study. Fiber properties have been shown to be strongly related to the solution viscosity and electrical conductivity. The addition of HNT increased the solution viscosity, thus resulting in the production of uniform fibers. For both PCL concentrations, the average fiber diameter increased with the increasing of HNT concentration. The average fiber diameters with HNT-ASP were reduced considerably in comparison to those with unmodified HNT when using 15 wt%/v PCL. Slightly better dispersion was obtained for PLA: PCL composites embedded with HNT-ASP compared to unmodified HNT. Furthermore, the addition of HNT-ASP to the polymeric blends resulted in a moderate decrease in the degree of crystallinity, as well as slight reductions of glass transition temperature of PCL, the crystallization temperature and melting temperature of PLA within composite materials. The infrared spectra of composites confirmed the successful embedding of HNT-ASP into PLA: PCL nanofibers relative to unmodified HNT due to the premodification using ASP to reduce the agglomeration behavior. This study provides a new material system that could be potentially used in drug delivery, and may facilitate good control of the drug release process. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7233-7 Authors Hazim J. Haroosh, Department of Chemical Engineering, Curtin University, Perth, WA 6845, Australia Yu Dong, Department of Mechanical Engineering, Curtin University, Perth, WA 6845, Australia Deeptangshu S. Chaudhary, Department of Chemical Engineering, Curtin University, Perth, WA 6845, Australia Gordon D. Ingram, Department of Chemical Engineering, Curtin University, Perth, WA 6845, Australia Shin-ichi Yusa, Department of Materials Science and Chemistry, University of Hyogo, Himeji, Hyogo, 671-2280 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Size dependence of transition enthalpy observed in ferroelectric PbTiO 3 nanoparticles has been shown to result from volume averaging or the surface dilution effect rather than size induced reduction of spontaneous polarization at the first-order phase transition temperature. The PbTiO 3 nanoparticles are suggested to be composed of a cubic surface layer with size independent thickness and a ferroelectric core having nonzero and size independent spontaneous polarization at the transition point. Based on a surface layer model, thickness of the cubic surface layer at the Curie temperature is estimated to be around 5–8 nm for PbTiO 3 nanoparticles from the literature-reported transition enthalpy data. The present analyses indicate that the size effect in ferroelectrics is possibly a surface related extrinsic effect. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7274-y Authors Wenhui Ma, Department of Physics, Shantou University, Shantou, Guangdong 515063, People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Femtosecond laser pulses can be absorbed by materials with larger energy band gap than the single photon energy through non-linear processes occurring in very small volumes. Thus, femtosecond lasers are exceptional tools for the modification of these materials with high resolution. This work is focused in the study of craters produced on the surface of a soda-lime glass after irradiation with a laser delivering 450 fs pulses at 1027-nm wavelength. The ablation with different energies and number of pulses is analyzed. Scanning electron microscopy and confocal microscopy are used to characterize the morphology of the ablation craters. The results show that micrometric resolution can be achieved with a focusing lens of 0.25 NA and pulse energies of few microjoules. The dependence of the laser fluence threshold on the number of pulses reveals the existence of an incubation effect. The trend for low number of pulses suggests a 4-photon ionization process. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7280-0 Authors J. M. Fernández-Pradas, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain D. Comas, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain J. L. Morenza, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain P. Serra, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    0.852[Bi 1/2 (Na 1− x Li x ) 1/2 ]TiO 3 –0.110(Bi 1/2 K 1/2 )TiO 3 –0.038Ba 0.85 Ca 0.15 Ti 0.90 Zr 0.10 O 3 (BNLT–BKT–BCTZ- x ) new ternary piezoelectric ceramics were fabricated by the conventional solid-state method, and their piezoelectric properties as a function of the Li content were mainly investigated. A stable solid solution with a single perovskite structure has been formed, and the depolarization temperature ( T d ) of these ceramics was identified by using the temperature dependence of the dielectric loss. The T d value of these ceramics gradually decreases, while the T m value increases with increasing the Li content. The dielectric constant increases and the dielectric loss decreases with increasing the Li content, and an enhanced piezoelectric behavior of d 33 ∼223 pC/N and k p ∼35.2 % has been demonstrated in these ceramics with x =0.06. Content Type Journal Article Category Rapid communication Pages 1-5 DOI 10.1007/s00339-012-7297-4 Authors Jiagang Wu, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Sha Qiao, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Jianguo Zhu, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Dingquan Xiao, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Polymer matrix nanocomposites filled with metallic and alloy nanoparticles add functionality in various applications such as optical devices and in the energy sector. However, matrix coupling agents or nanoparticle ligands may be unwanted additives, potentially inhibiting the resulting nanocomposite to be processed by injection molding. The generation of stabilizer-free Au, Ag, and AuAg alloy nanoparticle acrylate composites is achieved by picosecond-pulsed laser ablation of the respective metal target in the liquid monomer. Complementary to laser ablation of the solid alloy, we have alloyed nanoparticles by post-irradiation of Au and Ag colloids in the liquid monomer. The optical properties of the colloidal nanoparticles are successfully transferred to the solid poly(methyl methacrylate) matrix and characterized by their plasmon resonance that can be easily tuned between 400 and 600 nm by laser alloying in the liquid monomer. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7264-0 Authors Ana Menéndez-Manjón, Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover, 30419 Germany Andreas Schwenke, Laser Zentrum Hannover e.V., Hollerithallee 8, Hannover, 30419 Germany Timo Steinke, Deutsches Institut für Kautschuktechnologie e.V., Eupener Straße 33, Hannover, 30519 Germany Matthias Meyer, Deutsches Institut für Kautschuktechnologie e.V., Eupener Straße 33, Hannover, 30519 Germany Ulrich Giese, Deutsches Institut für Kautschuktechnologie e.V., Eupener Straße 33, Hannover, 30519 Germany Philipp Wagener, Technical Chemistry, University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CeNiDE), Duisburg, Germany Stephan Barcikowski, Technical Chemistry, University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CeNiDE), Duisburg, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The crystalline structure, surface morphology, electrical, and optical properties of thin films of nanocomposites consisting of silver nanoparticles embedded in poly( p -xylylene) matrix prepared by low-temperature vapor deposition polymerization were studied. Depending on the filler content, the average size of silver nanoparticles varied from 2 to 5 nm for nanocomposites with 2 and 12 vol.% of silver, correspondingly. The optical adsorption in the visible region due to surface plasmon resonance also exhibited a clear correlation from silver content, revealing a red shift of the adsorption peak with the increase of the metal concentration. The temperature dependences of the dc resistance of pure p -xylylene condensate and p -xylylene–silver cocondensates during polymerization as well as temperature dependences of the formed poly( p -xylylene)–silver nanocomposites were examined. The observed variation of the temperature dependences of electrical resistance as a function of silver concentration are attributed to different conduction mechanisms and correlated with the structure of the composites. The wide-angle X-ray scattering and AFM measurements consistently show a strong effect of silver content on the nanocomposite structure. The evolution of the size of silver nanoparticles by thermal annealing was demonstrated. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7220-z Authors Dmitry R. Streltsov, Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Moscow, Russia Karen A. Mailyan, Institute for Theoretical and Applied Electromagnetics of the Russian Academy of Sciences, Moscow, Russia Alexey V. Gusev, Institute for Theoretical and Applied Electromagnetics of the Russian Academy of Sciences, Moscow, Russia Ilya A. Ryzhikov, Institute for Theoretical and Applied Electromagnetics of the Russian Academy of Sciences, Moscow, Russia Natalia A. Erina, Bruker-Nano Inc., Santa Barbara, CA, USA Chanmin Su, Bruker-Nano Inc., Santa Barbara, CA, USA Andrey V. Pebalk, National Research Centre “Kurchatov Institute”, Moscow, Russia Sergei A. Ozerin, Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Moscow, Russia Sergei N. Chvalun, Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Moscow, Russia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Microscopic mechanisms and optimization of metal nanoparticle size distribution control using femtosecond laser pulse trains are studied by molecular dynamics simulations combined with the two-temperature model. Various pulse train designs, including subpulse numbers, separations, and energy distributions are compared, which demonstrate that the minimal mean nanoparticle sizes are achieved at the maximal subpulse numbers with uniform energy distributions. Femtosecond laser pulse trains significantly alter the film thermodynamical properties, adjust the film phase change mechanisms, and hence control the nanoparticle size distributions. As subpulse numbers and separations increase, alternation of film thermodynamical properties suppresses phase explosion, favors critical point phase separation, and significantly reduces mean nanoparticle size distributions. Correspondingly, the relative ratio of two phase change mechanisms causes two distinct nanoparticle size control regimes, where phase explosion leads to strong nanoparticle size control, and increasing ratio of critical point phase separation leads to gentle nanoparticles size control. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7269-8 Authors Xin Li, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 People’s Republic of China Lan Jiang, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    In this work, we report an approach to fabricate molecular junctions based on metal oxide thin films with nanoscale cracks. The growth of the cracked oxide films is systematically investigated, which reveals that the crack width can be tuned by varying the dopants and/or the heating rate. Current-voltage measurements show that the as-fabricated molecular junction exhibits stable and reproducible electrical switching performance. The ON state junction obeys the Ohmic conduction, while the OFF state follows the space-charge-limited transport. The switching mechanism is shown to be governed by a charge trapping/detrapping process taken place in the organic active layer. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7284-9 Authors J. C. Li, Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang, 110819 China X. Gong, Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang, 110819 China D. Wang, Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang, 110819 China D. C. Ba, Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang, 110819 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Transport characteristics of relativistic electrons through graphene-based d -wave superconducting double barrier junction and ferromagnet/ d -wave superconductor/normal metal double junction have been investigated based on the Dirac–Bogoliubov–de Gennes equation. We have first presented the results of superconducting double barrier junction. In the subgap regime, both the crossed Andreev and nonlocal tunneling conductance all oscillate with the bias voltage due to the formation of Andreev bound states in the normal metal region. Moreover, the critical voltage beyond which the crossed Andreev conductance becomes to zero decreases with increasing value of superconducting pair potential  α . In the presence of the ferromagnetism, the MR through graphene-based ferromagnet/ d -wave superconductor/normal metal double junction has been investigated. It is shown that the MR increases from exchange splitting h 0 =0 to h 0 = E F (Fermi energy), and then it goes down. At h 0 = E F , MR reaches its maximum 100. In contrast to the case of a single superconducting barrier, Andreev bound states also manifest itself in the zero bias MR , which result in a series of peaks except the maximum one at h 0 = E F . Besides, the resonance peak of the MR can appear at certain bias voltage and structure parameter. Those phenomena mean that the coherent transmission can be tuned by superconducting pair potential, structure parameter, and external bias voltage, which benefits the spin-polarized electron device based on the graphene materials. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7275-x Authors Chunxu Bai, School of Physics, Anyang Normal University, Anyang, 455000 China Ke-Wei Wei, School of Physics, Anyang Normal University, Anyang, 455000 China Gui Yang, School of Physics, Anyang Normal University, Anyang, 455000 China Yanling Yang, School of Physics, Anyang Normal University, Anyang, 455000 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    In order to understand the behavior of the different dye-sensitized solar cell (DSC) components, an in-situ analysis should give fundamental help but it is impossible to be performed without compromising the integrity of the cell. Our recently proposed novel microfluidic approach for the fabrication of DSCs is based on a reversible sealing of the two transparent electrodes and it allows the easy assembling and disassembling of the cell, making possible an analysis of the components over time. The aim of this work is not to investigate the different degradation mechanisms of a standard DSC: we want to show that, by using a microfluidic architecture, it is possible to perform a non-destructive analysis and to monitor the photoanode and the counter electrode properties during their lifetime. Morphological (field emission scanning electron microscopy), wetting (contact angle), optical (UV-visible spectroscopy) and electrical (current–voltage and electrochemical impedance spectroscopy measurements under standard AM1.5G illumination) characterizations have been performed over a period of three weeks. The results show how the variation of the wetting and morphological properties at the counter electrode and of the dye absorbance at the photoanode are strongly related to the decrease of the cell performances as evidenced by electrical characterization, thus demonstrating the effectiveness of the use of our structure in this kind of studies. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7268-9 Authors A. Sacco, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy A. Lamberti, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy D. Pugliese, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy A. Chiodoni, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy N. Shahzad, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy S. Bianco, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy M. Quaglio, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy R. Gazia, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy E. Tresso, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy C. F. Pirri, Center for Space Human Robotics @PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, Torino, 10129 Italy Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The vertical movement of a 40 nm thin Au film on a silicon substrate during intense nanosecond (ns) laser irradiation is determined on the nm vertical and ns time scales using an optimized Michelson interferometer. The balanced setup with two detectors uses the inverse interference signal and accounts for transient reflectivity changes during irradiation. We show that a change in phase shift upon reflection must be taken into account to gain quantitative results. Three distinct fluence regimes can be distinguished, characterized by transient reflectivity behavior, dewetting processes and film detachment. Maximum displacement velocities are determined to be 0.6 m/s and 1.9 m/s below and above the melting threshold of the metal, respectively. Flight velocities of detaching liquid films are found to be between 30 and 70 m/s for many nanoseconds. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7235-5 Authors F. Kneier, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany T. Geldhauser, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany E. Scheer, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany P. Leiderer, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany J. Boneberg, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Electromechanical interaction determines the structural reliability of electronic interconnects. Using the nanoindentation technique, the effect of alternating electric current on the indentation deformation of copper strips was studied for the indentation load in a range of 100 to 1600 μN at room temperature. During the test, an alternating electric current of the electric current density in a range of 1.25 to 4.88 kA/cm 2 was passed through the copper strips. The indentation results showed that the reduced contact modulus decreased linearly with increasing the electric current density. The indentation hardness decreased with increasing the indentation deformation, demonstrating the normal indentation size effect. Using the model of strain gradient plasticity, we found that the strain gradient underneath the indentation decreased slightly with increasing the electric current density for the same indentation depth. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7078-0 Authors Guangfeng Zhao, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA Fuqian Yang, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    Vapor expansion from Al target irradiated by a continuous wave laser into a supersonic external air flow is investigated in kinetic simulations performed for values of pressure in the external flow ranging from 50 Pa to 10000 Pa. The direct simulation Monte Carlo method enhanced with a simplified description of Al vapor burning in air is used in the simulations. The results of the simulations reveal a significant effect of the external gas pressure on the flow structures and the mechanisms of the alumina and oxygen transport to the target surface. At small values of pressure, the transport of both alumina and oxygen is controlled by diffusion and the formation of alumina film on the surface of the laser spot is dominated by the direct sedimentation of alumina from the gas flow. In this regime, the flux of oxygen to the laser spot is by an order of magnitude smaller than that of alumina. At higher values of pressure, the diffusion cannot directly deliver oxygen and alumina to the surface of the laser spot, but the circulating flow generated upstream the spot can effectively trap alumina formed in the flame zone and deposit it to the target surface. In this regime, the likely mechanism of the alumina film formation within the spot is the heterogeneous oxidation and growth of the film from the upstream edge of the spot in the downstream direction. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7290-y Authors Alexey N. Volkov, Department of Materials Science and Engineering, University of Virginia, 395 McCormick Road, Charlottesville, VA 22904-4745, USA Leonid V. Zhigilei, Department of Materials Science and Engineering, University of Virginia, 395 McCormick Road, Charlottesville, VA 22904-4745, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    We perform polarized Raman spectroscopy on aligned single-walled carbon nanotubes. This test system allows us to empirically address if resonant Raman scattering from on-axis dipole transitions follows a cos 2 or a cos 4 mosaic spread. We observe in the polar plots a clear cos 4 dependence, in agreement with the equivalency of incoming and outgoing dipole transitions. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7305-8 Authors Christian Kramberger, Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria Theerapol Thurakitseree, Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan Shohei Chiashi, Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan Erik Einarsson, Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan Shigeo Maruyama, Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Description:    The effect of the second and later pulses on the expansion dynamics of the cavitation bubble produced by multi-pulse microchip laser irradiation of a Cu target in water has been investigated. We clarified the bubble dynamics by taking shadowgraph images and measuring the bubble radius as a function of time. Shock waves were also measured to investigate the explosive expansion of the bubble. As a result, the second and later pulses did not cause an explosive expansion, and the ablation of the target by these pulses was rather mild, although they had a certain contribution to the expansion of the bubble. The energies given to the bubble expansion from the first pulse and also from the second pulse were estimated by comparing the experimental results with the calculation based on the Rayleigh model. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7291-x Authors Ayaka Tamura, Institute of Advanced Energy, Kyoto University, Gokasho, Uji-shi, Kyoto, 611-0011 Japan Tetsuo Sakka, Institute of Advanced Energy, Kyoto University, Gokasho, Uji-shi, Kyoto, 611-0011 Japan Kazuhiro Fukami, Institute of Advanced Energy, Kyoto University, Gokasho, Uji-shi, Kyoto, 611-0011 Japan Yukio H. Ogata, Institute of Advanced Energy, Kyoto University, Gokasho, Uji-shi, Kyoto, 611-0011 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396