Materials Literature
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Hydrated tungsten peroxides have been synthesized via the reaction of tungstic acid, H 2 WO 4, with aqueous solutions of hydrogen peroxide. Two crystalline phases with the formula [WO 2 (O 2 )H 2 O]· n H 2 O were obtained. X-ray powder diffraction data show that these two phases crystallize with monoclinic symmetry. T…
A crystal surface which is miscut with respect to a high symmetry plane exhibits steps with a characteristic distance. It is argued that the continuum description of growth on such a surface, when desorption can be neglected, is given by the anisotropic version of the conserved KPZ equation (T. Sun, H. Guo, and M. Gra…
Four cobalt porphyrins were adsorbed on graphite electrodes and used to catalyze the electroreduction of O 2 . The two porphyrins without substituent groups in the meso positions of the porphyrin ring operated at the most positive potentials and catalyzed the reduction of O 2 to both H 2 O 2 and H 2 O, but the H 2 O d…
The properties of nanostructured plastics are determined by complex relationships between the type and size of the nanoreinforcement, the interface, and the chemical interaction between the nanoreinforcement and the polymeric chain, along with macroscopic processing and microstructural effects. Recently, families of m…
Thin-film BaTiO 3 has been prepared for the first time by spray pyrolysis. Both smooth and highly porous films were deposited depending on deposition temperature and rate. As-deposited films contained an unidentified, low-symmetry barium titanate modification. Annealing at 500−900 °C converted the films to the cubic p…
Optical Kerr effect spectroscopy has been used to monitor the orientational dynamics of acetonitrile in the bulk and confined in nanoporous silicate glasses. While the orientational decay in the bulk liquid is described by a single exponential, the confined liquid decays are best described by the sum of three exponent…
Similarity submodules and semigroups by M. Baake and R. V. Moody Pisot-cyclotomic quasilattices and their symmetry semigroups by D. Barache, B. Champagne, and J.-P. Gazeau Three possible branches of determinate modular generalization of crystallography by N. A. Bulenkov Non-crystallographic root systems by L. Chen, R.…
Anhydrous AlPO 4 -17 has been found to experience a very strong negative thermal expansion over the temperature range 18−300 K. Powder synchrotron X-ray diffraction data taken at six temperatures over this range show an essentially linear decrease in cell volume, with a linear coefficient of thermal expansion of −11.7…
We investigate the energetics of the single-period and double-period core reconstructions of the 90-degree partial dislocation in the homopolar semiconductors C, Si, and Ge. The double-period geometry is found to be lower in energy in all three materials, and the energy difference between the two geometries is shown t…
We propose a model based on a Ginzburg-Landau approach to study a strain relief mechanism at a free interface of a non-hydrostatically stressed solid, commonly observed in thin-film growth. The evolving instability, known as the Grinfeld instability, is studied numerically in two and three dimensions. Inherent in the…
A polar asymmetry of electro-optical behavior has been studied for a liquid-crystal cell, one electrode of which is covered by a thin film of a ferroelectric polymer. A well-known copolymer PVF2–TrFE (70:30) previously poled by a corona discharge has been used to modify the quadratic electro-optical response of the ne…
The behavior of luminescence spectra and structural defects in single crystal Czochralski silicon after erbium implantation at 1 MeV energy and 1×1013 cm−2 dose with subsequent annealing at 1100 °C for 0.25–3 h in an argon or chlorine-containing ambience was studied by photoluminescence (PL), transmission electron mic…
We report results of high-speed polarization relaxation measurements in ferroelectric thin film capacitors. Polarization relaxation has been reported to occur in two distinct time regimes, one for relaxation times in the range of a few milliseconds and a second for longer relaxation times. We find that the polarizatio…
The multiple scattering interferences due to the addition of several contiguous potential units are used to construct composite complex potentials that absorb at an arbitrary set of incident momenta or for a broad momentum interval.
We apply Pauli's master equation to spin tunneling in ${\mathrm{Mn}}_{12}$ acetate, and argue that the corresponding relaxation is exponential in time. Taking advantage of this simplification we calculate the frequency dependent specific heat. The results are compared with recently obtained experimental ones. We also…
Recent experiments by Lee et al. [Nature (London) 363, 255 (1997)] show that doping carbon single-wall nanotube (SWNT) ropes with K, Rb, or ${\mathrm{Br}}_{2}$ leads to metallic conductivity, but the structure and properties are not known. We used molecular dynamics to predict structures and properties which should he…
The powder IR phonon spectra of synthetic garnets of the six binaries in the system Mg3Al2Si30i2 (Pyrope - Py) - Fe3Al2Si30i2 (Almandine - Al) - Mn3Al2Si3Oi2 (Spessartine - Sp) - Ca3AbSi30i2 (Grossular - Gr) have been recorded and analyzed. Between 14 and 17 Fiu-symmetry infrared active modes were observed for the dif…
We have used a metal–oxide bilayer Raman scattering technique to study lattice dynamics in SrTiO3 thin films. The SrTiO3 thin films were epitaxially grown on a conducting metal–oxide layer which reflects the exciting laser beam so that it does not enter the LaAlO3 substrate. Raman scattering from the SrTiO3 thin films…
Thirty one layer TiO2/SiO2 optical filters with graded refractive index profiles were fabricated by helicon plasma sputtering at room temperature. Multilayer films were deposited on glass (BK7) and Si (100) substrates simultaneously and sequentially. The measured transmittance spectrum exhibited a reflectance of 99.8%…
We report the molecular beam epitaxy (MBE) growth of the manganese(II) phthalocyanine thin films with unique crystal structure and the measurement of their magnetic properties. The epitaxial films were grown on hydrogen-terminated Si(111) substrates. Reflection high energy electron diffraction observations showed that…