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  • 1
    Electronic Resource
    Electronic Resource
    Development of Low Carbon Boron Steel for Wire Drawing (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 539-543 (Mar. 2007), p. 4238-4242 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: From the mechanical point of view, the successful cold drawing of wire-rods of low carbonsteel requires a high ductility and a ratio between the yield stress and tensile strength as lowest aspossible, both for diminish the fractures during the process. Small boron additions in the cast of thiskind of steel produce an increase in the size of austenitic grain, and consequently the ferritic one, anda diminution of the deformation hardening due to the reduction in the nitrogen content in the solidsolution. In this way, the goal of this work is to study the effect of small boron additions (67 to 117ppm) in the mechanical properties of 5.5 mm diameter wire-rods of low carbon steel.The wire-rods were characterized by means of traction tests, metallographic analysis with optic andelectronic microscopy, and the results were compared with the corresponding one for wire-rod ofstandard steel, i.e., without boron contents.The metallographic analysis confirms the increase in size of ferritic grain. The measured ductilitypresent only slight increases in boron steel, no significant from the quality point of view, however, theratio between yield stress and tensile strength in boron steels shown a clear improvement respect tothe standard. Traction tests in samples obtained at the exit of each one of the matrixes used during thecold drawing process shows an improve in the behavior of low carbon steel with boron contents
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.4238.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Nanostructure Epitaxial diamond polytypes on silicon (2001)
    [s.l.] : Nature Publishing Group
    Nature 412 (2001), S. 404-404 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Carbon is unique in the variety of configurations it can adopt with itself and other elements. Here we show how ion beams can be used to nanostructure various diamond polytypes, epitaxially aligning them to a silicon substrate. The ready controllability of ion beams, which are already used to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35086656
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  • 3
    Electronic Resource
    Electronic Resource
    A new nucleation method by electron cyclotron resonance enhanced microwave plasma chemical vapor deposition for deposition of (001)-oriented diamond films (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 4616-4618 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new nucleation method, which is different from bias-enhanced nucleation, was employed for the preparation of (001)-oriented diamond films on untreated, mirror-polished silicon substrates. The nucleation was realized in an electron cyclotron resonance enhanced microwave plasma at a pressure of about 10−3 Torr which was 4 orders of magnitude lower than that normally used for bias-enhanced nucleation (∼tens Torr). Scanning electron microscopy and Raman spectroscopy were used to investigate the surface morphology and phase purity of the deposited diamond films. The new findings may provide us a route to further understand the nucleation mechanism of diamond films by chemical vapor deposition. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478343
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  • 4
    Electronic Resource
    Electronic Resource
    Fluorine ion etching of lead zirconate-titanate thin films (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 300-302 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The etching reactions of lead zirconate-titanate (PZT) films with fluorine ions were studied by in situ x-ray photoelectron spectroscopic (XPS) analysis of the ion bombarded films. The bombardment was carried out with a mass separated low energy ion beam in ultrahigh vacuum and at 30 and 40 eV. It was found that the bombardment at 30 eV and a dose of 1×1017/cm2 (equivalent to 50 monolayers if a surface atom density of 2×1015/cm2 is assumed) at room temperature led to the removal of about 6 nm of PZT. This etch yield is much higher than the expected sputter yield at 30 eV, a phenomenon which clearly indicates the importance of surface chemistry. The XPS data also show that prior to bombardment, a homogeneous oxide was present but that the bombardment induced a surface enrichment of lead and the formation of metal fluorides. Heating the sample to 300 °C in vacuum desorbed virtually all metal fluorides. The results show that reactive ion etching of PZT films with fluorine chemistry is conceivable. However, the reaction mechanism appeared to be very much dependent on the bombardment energy. For example, an increase of the bombardment energy to 40 eV did not only increase the etch yield but also suppressed the surface enrichment of lead and induced the formation of oxy-fluorides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111185
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  • 5
    Electronic Resource
    Electronic Resource
    Argon incorporation in Si(100) by ion bombardment at 15–100 eV (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7101-7106 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Argon incorporation in Si(100) by low energy ion bombardment has been studied by polar angle dependent x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The bombardment was performed at 15, 20, and 100 eV in an ultrahigh vacuum chamber where a mass-separated argon ion beam with an energy spread of less than 1 eV was directed to the target. Both the argon penetration depth and incorporation probability were found to increase with bombardment energy. With a fluence of 2×1017/cm2, most of the incorporated argon was located within 20 A(ring) of the target surface for the 100 eV bombardment and within 10 A(ring) for the 15 eV bombardment. In all cases, the argon depth distribution reached a maximum and then declined. At this fluence, the incorporation probabilities were 0.0015 and 0.0004 for the 100 and 15 eV bombardment, respectively. When the amount of incorporated argon was measured as a function of fluence, it increased with fluence at low fluences, reached a quasisaturation at about 1×1016/cm2, but became fluence dependent again above 1×1018/cm2. The retained argon was stable at room temperature but showed at least two stages of thermal desorption in the temperature range 25–500 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355024
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  • 6
    Electronic Resource
    Electronic Resource
    Modification of surface band bending of diamond by low energy argon and carbon ion bombardment (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3385-3391 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Argon and carbon ion bombardment of p-diamond at 500–5000 eV in ultrahigh vacuum were studied by in situ x-ray photoelectron spectroscopy (XPS) and low energy electron diffraction analysis. Both argon and carbon ion bombardment at room temperature in the present energy range created a defective surface layer. The radiation damage was manifested by the introduction of a distinct C 1s peak (referred to as the "defect'' peak later) with a binding energy about 1 eV less than that of the bulklike diamond peak, and by the introduction of some additional filled states (referred to as the "filled states'') near the valence band edge of diamond. It was found that in comparison to argon bombardment, carbon bombardment was more efficient in producing the filled states but less efficient in raising the C 1s defect peak. While the filled states disappeared by annealing at about 500 °C, the C 1s defect peak did not change much even with a 1000 °C anneal. These results suggest that the C 1s defect peak, which has also been observed on reconstructed diamond surfaces after hydrogen desorption [see, e.g., B. B. Pate, Surf. Sci. 165, 83(1986)], is associated with vacancy formation and aggregation which give some "internal surfaces'' with a behavior like a reconstructed atomically clean diamond surface.The filled states introduced by ion bombardment are associated with interstitials or interstitial clusters. The amount of residual defects was found to increase with both an increasing bombardment dose and energy. For an argon bombardment at 1000 eV to a dose of 5×1014/cm2, the defective layer was estimated to be about 1.5 nm. Further, it was found that the radiation damage, particularly the "vacancy defects'', could only be annealed (at 1000 °C) when the dose was below 5×1014/cm2 at a bombardment energy of 500 eV. XPS band bending analyses also showed that room temperature bombardment induced a small reduction (0.2 eV) of the surface Fermi level position (EFs) on the p-diamond. However, subsequent vacuum annealing caused a rather large increase of EFs. But the EFs data from about 20 bombarded and annealed samples were always less than 2.2 eV. Thus the formation of an n-type diamond was not observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357016
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  • 7
    Electronic Resource
    Electronic Resource
    Synchrotron radiation x-ray absorption of ion bombardment induced defects on diamond (100) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7483-7486 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface defect structures on diamond (100) surfaces induced by 500 eV neon ion bombardment and by subsequent annealing were studied in situ with x-ray absorption near-edge structure (XANES) spectroscopy using 250–800 eV synchrotron radiation and with low energy electron diffraction. Ex situ x-ray photoemission spectroscopy (XPS) was also used to characterize the defective layer. Significant changes in the XANES spectra were identified for the defects induced by ion bombardment and subsequent annealing. The diamond discrete exciton absorption at 289.0 eV was clearly suppressed even at the lowest ion fluence used in this study, i.e., 3×1014/cm2, and no such exciton could be observed at 7×1014/cm2. However, the changes in the multi-maxima shape-resonance absorption structure in the range of 290–310 eV indicated that a loss of the diamond long range order required a fluence of 1×1015/cm2. The structural changes were also manifested by the transformation of gap state absorption typical of clean 2×1 surfaces to the π* absorption typical of amorphous carbon. XPS showed that the defective layer was about 2 nm thick. For all samples prepared with the bombardment conditions in the study, both the XANES and XPS data also indicated no phase transformation from defective layers to graphite even after annealing to a temperature of 1100 °C. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357977
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  • 8
    Electronic Resource
    Electronic Resource
    Interfacial characterization of ion-beam-deposited a-C films on Ge (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 552-557 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamondlike carbon films were deposited on germanium crystals with a mass-separated C+ ion beam in ultrahigh vacuum over the energy range 20–275 eV, and the interfaces were characterized with x-ray photoelectron spectroscopy. It was found that ion bombardment induced a carbide phase on the germanium surface. Further carbon accumulation then led to the growth of an amorphous carbon overlayer. The carbide phase was identified by a rather low C 1s binding energy (at about 283.8 eV) and small positive shift of the Ge 3p peak (about 0.4 eV). The valence-band spectra of these samples also suggested that germanium carbide formed with a pure carbon beam for the bombardment energy range considered has a band gap between germanium and diamondlike carbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357110
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  • 9
    Electronic Resource
    Electronic Resource
    Crystal morphology and phase purity of diamond crystallites during bias enhanced nucleation and initial growth stages (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3354-3360 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystal morphologies and phase composition of diamond crystallites during bias enhanced nucleation and initial growth stages in microwave plasma chemical vapor deposition were investigated. Diamond nuclei were first formed in the central regions of substrates and then propagated to the sample edges. During the course of bias nucleation, excessive ion bombardment induced secondary nucleation sites on the already formed nuclei. The secondary nucleation deteriorated the overall alignment of the growing crystals. Hence, the elimination of secondary nucleation and homogeneous nucleation over substrates are fundamental requirements for the deposition of large-area uniformly oriented diamond films. Decreasing reactant pressure was found to be effective for improving plasma homogeneity and consequently nucleation uniformity. The results of bias enhanced nucleation within a pressure range from 8 to 20 Torr showed that the lower pressure of reactants enlarged the area of oriented diamond films. However, the optimum bias and duration of nucleation was found to be specific for each pressure. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1289071
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  • 10
    Electronic Resource
    Electronic Resource
    Morphology of Si nanowires synthesized by high-temperature laser ablation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 7981-7983 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon nanowires have been synthesized by laser ablation of Si powder targets at 1200 °C. Transmission electron microscopy study showed that most Si nanowires had smooth surfaces and nearly the same diameter of about 16 nm. Beside the most abundant smooth-surface nanowires, four other forms of nanowires, named spring-shaped, fishbone-shaped, frog-egg-shaped, and necklace-shaped nanowires, were observed. The formation of nanowires into different shapes was explained by the two-step growth model based on the vapor–liquid–solid mechanism. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369389
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