Search results for "amorphous"
showing 10 items of 790 documents
Nonlinear optical properties of low molecular organic glasses formed by triphenyl modified chromophores
2012
The series of organic molecular glasses have been studied as possible candidates for nonlinear optical (NLO) applications. Amorphous phase formation of investigated materials is ensured by the presence of bulky triphenyl substituents in molecular structure of NLO chromophores. Linear optical properties as well as NLO coefficients and thermal stability of NLO activity for the 13 molecular materials in glassy thin solid films have been determined. For the benzylidene-1,3-indandione chromophore containing compound the highest d33 value equal to 280 pm/V was measured under the 1064 nm excitation. Among the investigated compounds uppermost achieved thermal sustainability of NLO response was 108 …
conversion electron Mössbauer study of low carbon steel polarized in aqueous sulfate solution containing sulfite in low concentration
1992
The passivation of low carbon steel was studied in aqueous solution of 0.5 M Na2SO4+0.001 M NaHSO3 at pH=3.5 and 6.5. The found major components at pH-3.5 were: γ-FeOOH and Fe3C, and also FeSO4.H2O could be identified on the surface of the low carbon steel as a minor component. At pH-6.5, the passive film contained only amorphous iron(III)-oxide or oxyhydroxide.
Ion-sputtering deposition of Ca–P–O films for microscopic imaging of osteoblast cells
2007
Abstract An ion-beam sputtering technique was used to produce Ca–P–O films on borosilicate glass at room temperature from hydroxyapatite targets using nitrogen, argon and krypton beams at different acceleration voltages. The sputtering target was pressed from high purity hydroxyapatite powder or mixture of high purity hydroxyapatite powder and red phosphorus in order to optimise the film composition. The film composition, determined using time-of-flight elastic recoil detection analysis (TOF–ERDA), was found to be strongly dependent on the ion energy used for deposition. By extra doping of the target with P the correct Ca/P atomic ratio in the deposited films was reached. The films deposite…
Germanium Doped CHxMicroshells for LMJ Targets
2011
AbstractAt the CEA Laser “Megajoule” facility, amorphous hydrogenated carbon (a-C:H or CHx) is the nominal ablator used to achieve inertial confinement fusion experiments. These targets are filled with a fusible mixture of deuterium-tritium in order to perform ignition.Since the achievement of ignition greatly depends on the physical properties of the shell, there must be precise control of thicknesses, doping concentration, and roughness. Experimental devices associated with suitable characterizations are described in this paper. The tolerances and yields for each specification are also presented. Some specifications are largely reached; high-frequency surface roughness due to isolated sur…
Effect of ion irradiation on the stability of amorphous Ge2Sb2Te5 thin films
2008
The archival life of phase-change memories (PCM) is determined by the thermal stability of amorphous phase in a crystalline matrix. In this paper, we report the effect of ion beam irradiation on the crystallization kinetics of amorphous Ge2Sb2Te5 alloy (GST). The transition rate of amorphous GST films was measured by in situ time resolved reflectivity (TRR). The amorphous to crystal transformation time decreases considerably in irradiated amorphous GST samples when ion fluence increases. The stability of amorphous Ge2Sb2Te5 thin films subjected to ion irradiation is discussed in terms of the free energy variation of the amorphous state because of damage accumulation. © 2008 Elsevier B.V. Al…
Formation of cobalt silicide from filter metal vacuum arc deposited films
2006
The thermal reaction of Co film deposited on Si(111) surfaces by a high current filter metal vacuum arc (FMEVAD) system has been studied. After deposition the films were annealed over the 400-900 degrees C temperature range for 30 min. Rutherford backscattering spectrometry (RBS) was used to characterize the elemental depth distributions in the films subjected to different annealing temperatures. Ordered chemical phases were determined by glancing-incidence X-ray diffraction (GIXRD) and the morphology was determined by cross section transmission electron microscopy (TEM). The results show that the phases formed are Co2Si at 400 degrees C, CoSi + Coo at 500 degrees C, CoSi + CoSi2 at 600 deg…
Study of Fe−Ti and Fe−TiN interfaces by conversion electron Mössbauer spectroscopy
1992
Titanium and titanium nitride-iron interfaces obtained by PVD coated thin films of Ti and TiN onto argon plasma etched iron substrates at various temperatures and negative bias were studied by use of CEMS. It was found that intermixing to Ti with Fe resulted in the appearance of an amorphous FeTi1−x phase. Furthermore, a comparison of CEM spectra of samples before and after heating in UHV has shown rather strong influence of thermal treatments on Fe/Ti as well as Fe/TiN interfaces.
Oxygen-excess-related point defects in glassy/amorphous SiO2 and related materials
2012
Abstract An insight is given into recent experimental advances in the spectroscopic studies of oxygen-excess intrinsic defects, in glassy SiO 2 and α-quartz. By controlling excess oxygen in a-SiO 2 , and the conditions of F 2 -laser irradiation, SiO 2 glass samples can be obtained with optical absorption almost exclusively dominated by single defect, oxygen dangling bonds (“non-bridging oxygen hole centers” or NBOHCs), without the presence of complementary Si dangling bonds (generic “E′-centers”). This allows for a more accurate determination of the spectral shape of NBOHC optical absorption in UV and vacuum UV spectral regions. The temperature dependence of NBOHC electron paramagnetic reso…
Niobium implantation effects in BaTiO3 and SrTiO3
1992
Abstract Single crystals of BaTiO3 and SrTiO3 have been implanted at room temperature with 150 keV Nb+ ions to doses ranging from 1014 to 1017 ions cm2. The structure and the oxidation state of the damaged layer have been investigated by Rutherford backscattering-ion channeling and electron spectroscopy, respectively. SrTiO3 is rendered amorphous at relatively low doses of 2 × 1015 ions cm−2, but the damage is efficiently annealed at 450°C for 1 2 h. For both materials, the oxidation state of niobium varies from + 5 to + 2 along the depth. Moreover, a considerable chemical shift (2.3 eV) is observed for barium in BaTiO3.
Comparison Between Point Defect Generation by $\gamma$-rays in Bulk and Fibre Samples of High Purity Amorphous ${\hbox {SiO}}_{2}$
2008
We compare the E', H(I) and Si-ODC(II) contents in a low-OH high-purity a-SiO2 either in bulk or fibre forms. We found that the H(I) centre appears during irradiation and tend to increase with the dose if the fibre contains hydrogen excess. This behaviour is believed to be one the possible reason to explain the apparent radiation-sensitivity enhancement in the blue-UV spectrum when the fibre is hydrogenated and irradiated at high dose. However for the hydrogen-treated fibres, no experimental repeatability could be evidenced in the measurements of E' and Si-ODC(II) although an acceptable agreement was still found in normal samples. This suggests a possible complex reactional mechanisms in pr…