Materials Literature
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We report the results of ab initio total-energy pseudopotential calculations, high-pressure angle-dispersive powder x-ray diffraction, and vibrational spectroscopy measurements on the IV-VI layered semiconductor germanium selenide (GeSe). The calculated hydrostatic pressure dependence of the crystal structure is found…
The epitaxial-like BaTiO3 (BTO) films with good ferroelectricity are obtained both on (001)SrTiO3 (STO) single crystal and on CeO2 buffered silicon substrate by pulsed laser deposition. The deposition parameters need to be stringently controlled in order to grow BTO films with good crystallinity. The BTO films grown o…
The nature of the metal-insulator (MI) transition of α -(ET) 2 I 3 has been studied theoretically. The effect of the on-site Coulomb interaction has been investigated at absolute zero within the Hartree-Fock approximation. If the Coulomb interaction exceeds some critical value, charge transfer occurs between different…
The lifetimes of the excited state of the tetrahedrally coordinated ${\mathrm{Cr}}^{4+}$ ion in several garnets were measured in the temperature range between 15 and 380 K. Both the nonradiative and radiative transition rates increase with temperature due to the coupling of phonons to the electronic states. This tempe…
Switchable polarization can be suppressed in Pb(Zr,Ti)O3 thin films by optical, thermal, electrical, and reducing processes. The optical suppression effect occurs by biasing the ferroelectric near the switching threshold and illuminating the material with band gap light; the thermal suppression effect occurs by biasin…
The intrinsic decay dynamics of pair excitations involving a deep donor and a shallow acceptor in chemical-vapor-deposited diamond is studied by time-resolved photoluminescence. Appropriate excitation conditions result in a distinctive decay behavior of individual donor-acceptor pair excitations, with extremely short…
Electronic structures of ${\mathrm{MoS}}_{2}$ and ${\mathrm{MoSe}}_{2}$ surfaces are investigated by first-principles electronic-structure calculations. The ultrasoft pseudopotential by Vanderbilt is used to perform band calculations with a plane-wave basis. Calculated band structures are consistent with recent calcul…
Fused Silica is the material of choice for UV optical systems such as the projection optics in microlithography systems. Unfortunately fused silica is not stable under UV irradition and undergoes compaction and color center formation. The UV damage properties of fused silica have been the subject of a number of studie…
Synthetic diamonds have been grown from metal melts containing silicon, at high pressures and high temperatures. The absorption and photoluminescence spectra have been investigated in the temperature range 1.8--77 K. A 12-line fine structure is observed close to 1.682 eV, and this can be divided into three similar gro…
Electronic structures of Heusler alloys Co 2 MnZ (Z=sp elements) were calculated to search half-metallic compounds. In this paper, it will be shown that stoichiometric compounds Co 2 MnZ are half-metallic when Z is Si and Ge. Considering the effect of Z atom on the band structure, we can predict that there are half-me…
The theory of lineshapes of satellites in photoelectron spectra in a simplified fourth-order perturbation theory is developed. The calculation of the monopole satellites of the 2p ionization of the neon atom has been carried out in second- and simplified fourth-order perturbation theory. The theoretical linewidths and…
CaSO 4 :Dy and CaSO 4 :Tm are highly sensitive phosphors used in the thermoluminescence (TL) dosimetry of the ionizing radiations. It is shown that, by using P, Mo or SO 3 as co-dopants, the TL sensitivities can be increased by 40-100%. The increase in sensitivity originates in various processes, which are discussed.…
Space charges formed in low-density polyethylene (LDPE), to which high voltage is applied, are usually composed of injected homocharges from electrodes and ionized heterocharges from bulk impurities. In this paper, the heterocharges in LDPE were discriminated from homocharges using charge-injection suppression layers.…
Hexagonal ZnO films were deposited on a glass substrate at room temperature by RF sputtering a ZnO target using a mixture of oxygen and argon. Polycrystalline ZnO films prepared in the presence of excess oxygen or at a high oxygen pressure tend to have crystallites with the orientation of the c-axis parallel to the su…
Ab initio molecular dynamics simulations are used to investigate the structure and electronic properties of the liquid Ag-Se system at three compositions. The realism of the simulations is demonstrated by comparison with diffraction data for the stoichiometric case Ag$_2$Se. As the Se content is increased beyond the s…
Abstract We examined the influence of polyaniline (PAn)'s unit sequence and doping with low molecular weight dopants or polymer dopants on permeation property. It was found that CO 2 permeability was increased by the formation of a quinonediimine unit in PAn with the oxidation. CO 2 sorption amount of PAn was decrease…
Abstract Biodegradable poly(1,4‐butanediol succinate) was synthesized from 1,4‐butanediol and succinic anhydride. The synthesized polymer was identified by 1 H‐NMR spectrometer and FT‐IR spectrophotometer. The weight average molecular weights were between 4,600 and 29,000, and molecular weight distributions were in th…
Abstract Grafting dicarboxylic anhydrides onto polyolefins has great practical importance. The process of grafting maleic anhydride onto high‐density polyethylene in the presence of various comonomers in an intermeshing corotating twin‐screw extruders was studied. Three types of comonomers were investigated: (i) vinyl…
Abstract The cure kinetics of a diglycidyl ether of bisphenol A (DGEBA)‐based epoxy resin with methyltetrahydrophthalic anhydride and an accelerator was studied by nonisothermal DSC data. The systems were uncured resin and partially cured with the following extents of cure measured by the residual heat method (α DSC )…
Epitaxial SrTiO3 thin films were prepared using low pressure metalorganic chemical vapor deposition. The volatile metalorganic precursors employed were Sr(hexafluoroacetyl acetonate)2⋅tetraglyme and titanium tetraisopropoxide. Single-phase, epitaxial films were deposited on (100)LaAlO3 at a temperature of 810 °C. In-p…