Materials Literature
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Pulsed laser irradiation is used to heat deeply buried damage layers in diamond. Over a small range of laser powers, damage annealing, formation of buried graphitic layers, and melting of diamond followed by its conversion upon cooling into graphite are observed. The diagnostics employed are channeling contrast micros…
We have studied and compared the optical properties of both porous Si and the chemically synthesized planar and cubic Si skeleton clusters. Broad photoluminescence with large Stokes shifts were observed at the visible region in both samples. Spectroscopic analysis suggests that the surface of porous Si is similar to a…
Reflection high-energy electron diffraction oscillations during pulsed laser ablation of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{x}}$ on ${\mathrm{SrTiO}}_{3}$(100) substrates were measured. We have found for the first time that the oscillations are modulated by the laser-…
The (2\ifmmode\times\else\texttimes\fi{}1) reconstruction of the (111) surface of diamond has been characterized via a series of first principles molecular dynamics calculations. The reconstructed clean surface is found to consist of dimerized \ensuremath{\pi}-bonded chains with no buckling and to be stable against th…
The mixed ferrite Cu1−xTixFe2O4 (where x = 0 to 0.7) are prepared by the ceramic method. X-ray diffraction and IR absorption spectra in the range from 200 to 1000 cm−1 are used for analysing the compositions. It is observed that samples with x ≦ 0.4 exhibit spinel phase, whereas for x > 0.4 mixed phases of spinel and…
We have investigated the generation of the pretilt angles for nematic liquid crystal (5CB) aligned in the cells using rubbed polyimide (PI) films containing trifluoromethyl moieties as a function of rubbing strength (RS). In order to characterize the films, we have conducted an analysis of the surface atomic concentra…
252Cf plasma desorption mass spectrometry has been used in the characterization of more than 100 synthetic porphyrins ranging in mass from 614 u for tetraphenylporphyrin to over 2000 u for some porphyrin model systems. In virtually every case, 252Cf plasma desorption mass spectrometry yielded an intense ionized molecu…
Contrairement aux resultats anterieurs, la phase III ( qui est stable entre 279 et 302 K ), est triclinique avec une petite deviation a partir d'une maille monoclinique centree C. La deformation triclinique et la presence de deux groupes H(SeO 4 ) 2 non equivalents sont en bon accord avec les mesures RPE.
The structure of antiphase domain boundaries in the ordered phase of body-centered-cubic alloys is investigated by Monte Carlo simulations, studying a fairly realistic model of iron-aluminum alloys that includes a description of the magnetic properties of iron within a nearest-neighbor Heisenberg Hamiltonian. An inter…
Auger electron spectroscopy has been employed to investigate the effectiveness of thin films of TiN as barriers to carbon diffusion during chemical vapor deposition (CVD) of diamond onto Fe substrates. Auger depth profiling was used to monitor the C concentration in the TiN layer, through the interface and into the su…
Abstract To clarify how the biodegradation of plastic is affected by physical properties based on the plastic's higher‐order structure, the microbial degradability of heat‐treated poly(3‐hydroxybutyrate) (PHB) samples was studied. Cast‐film samples and fibrous samples prepared with heat treatment were degraded by an i…
We show that there is no correlation between the blue shift of the visible photoluminescence band and red shift of the Raman phonon line in porous silicon, in contrast to the recently reported results. We also report a drastic red shift of the photoluminescence peak position with pressure up to 6 GPa and show that thi…
Structural imperfections in silica glasses with an optical absorption peak at 3.8 eV were studied. The 3.8-eV peak was assigned to Cl2 molecules trapped in the glasses. The peak absorption was increased with increasing partial pressure of chlorine for sintering. The peak and its full width at half maxima were the same…
Abstract The effect of welding pressure and surface contaminants on butt fusion in a commercial polyethylene gas pipe was studied by measuring the slow crack growth resistance of the joint. Two weld pressures, 1.61 and 0.31 MPa, were used. The contaminants Vaseline, graphite, and Teflon were coated on the surface. It…
Raman scattering spectra of LO phonon modes in CdS microcrystals having various sizes in a germanium dioxide glass matrix are measured. The bandwidth of the LO phonon broadens with decreasing the microcrystal size. The size dependence of the bandwidth agrees with the calculated results based on the phonon confinement…
The theoretical treatment of the diffuse scattering including the correlations among the thermal displacements of atoms were described. It was applied to the analysis of the observed intensities of the diffuse scattering of α-AgI. The same thermal parameters which were obtained from the analysis of Debye lines based o…
Abstract A dynamic mechanical thermal analyzer (DMTA) was used to monitor changes of dynamic mechanical properties during thermal degradation of two types of epoxy/silica composites, both of which are used as electrical insulation in power apparatus. It was found that the peak value of the dynamic loss factor (tan δ),…
A systematic analysis of the electronic structure of ${\mathrm{As}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{As}}_{2}$${\mathrm{O}}_{5}$, ${\mathrm{Ga}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{GaAsO}}_{4}$ is made both experimentally and theoretically. The comparison between x-ray-photoemission spectra and tight-binding calcul…
We present computer simulation data for the dielectric constant of a system of uniform polarizable spheres randomly distributed in a homogeneous background. The deviations from the Clausius-Mossotti formula are found for seven values of the volume fraction. In addition, the spectral density which appears in the Bergma…
We present a comprehensive study of epitaxially grown and As-coated GaAs(100) surfaces as a function of As desorption temperature and background pressure. We have used low-energy electron diffraction to determine surface reconstruction, and core-level and valence-band soft-x-ray photoemission spectroscopy to perform c…