Materials Literature
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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…
Magnetization measurement and 55 Mn NMR study on a ferromagnet system La(Ni 2+ 1- x Mg x 2+ ) 0.5 Mn 0.5 4+ O 3 are made. The divalent and the tetravalent ions are found to be ordered to a considerable extent in the whole compositional range, and the ferromagnetic superexchange interactions between neighboring Mn 4+ a…
The electronic transport mechanism in polypyrrole is discussed in terms of Mott variable range hopping (VRH) in samples with a wide range of conductivities and which have been formed using different doping techniques. Samples were synthesized in both aqueous and organic media and samples were either doped during polym…
The microscopic mechanism of oxygen diffusion in yttria stabilized zirconia (YSZ) is investigated by means of a polyhedron analysis. It is shown that the probability of finding O ion in a tetrahedron increases as Y ions at the corners of the tetrahedron increase, and this tendency becomes marked with increasing dopant…
Thermally generated defects in ultrathin MgO films on Mo(100) have been investigated using high-resolution electron-energy-loss spectroscopy (HREELS) in the 0--9-eV spectral region. The results indicate that the MgO films are thermally stable and nearly free from defects up to a temperature of 1100 K, above which defe…
We have fabricated boron carbide thin films on Si(111) and other substrates by plasma-enhanced chemical-vapor deposition (PECVD). The PECVD of boron carbides from nido-cage boranes, specially nido-pentaborane(9) (B5H9), and methane (CH4) is demonstrated. The band gap is closely correlated with the boron to carbon rati…
We have recently demonstrated that the Meyer-Neldel (MN) rule (compensation law) may be understood as arising naturally when the activation energy for a process is significantly larger than both the typical excitations available and kT. This conclusion was supported by the results of two microscopic models, related to…
We demonstrate a cluster expansion technique that is capable of accurately predicting formation energies in binary substitutional systems---even for those with large atomic relaxations. Conventional cluster expansions converge rapidly only in the absence of atomic relaxations, and they fail for long-period lattice-mis…
We present an efficient scheme for including full-potential terms in the linear-muffin-tin-orbital method. It is based on direct evaluation of the integrals in the interstitial region by partitioning crystalline space into atomic-cell envelopes and using one-center spherical harmonics expansions. This leads to a fast…
It is established that vacancies in diamond migrate, during annealing, primarily in their neutral charge state, with an activation energy of 2.3\ifmmode\pm\else\textpm\fi{}0.3 eV. Negative vacancies are destroyed by first converting to neutral centers in a reversible charge transfer process. In relatively pure diamond…