Materials Literature
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The electron velocity distribution is calculated for an idealized model of the high electron mobility transistor using a many-particle Monte Carlo model and a self-consistent two-dimensional Poisson solver. Hot electron effects, nonstationary effects, and real space transfer are analyzed. The results show that signifi…
We model the phonon spectra of the diamond-structure compounds C, Si, Ge, Sn and the zinc-blende-structure compounds GaP, GaAs, and ZnS. We use a four-parameter valence-force model consisting of first- and second-neighbor forces plus the very important coplanar angle-angle interaction introduced by McMurry et al. Alth…
The results of an experimental study of dc and microwave electrical conductivities, electron-spin resonance, optical reflection, and infrared absorption in ${\mathrm{FeCl}}_{3}$-doped polyparaphenylene (PPP) are presented. In low-conducting PPP, the conductivity is described by interpolaron hopping processes among the…
[ PtC12(C6 H 13N)(CsH 11P)] The shortest intermolecular contact [3.46 (2)A], observed between N and Cl(2)[~+x, ~--y, - z ] , is probably due to an N - H . . . C 1 hydrogen bond. The packing arrangement is shown in Fig. 3. Thanks are due to Dr G. Consiglio (ETH, Zfirich) who kindly prepared the compound. The drawings w…
Theoretical and experimental results describing the dependence of the Seebeck and Peltier coefficients on the composition of Ga1−xAlxAs solid solution are given. The Seebeck coefficient for nondegenerately doped n- and p-type Ga1−xAlxAs is given by the simple expressions αn=(k/e)(lnNc/n+2) and αp=−(k/e)(lnNv/p+2), res…
We have studied the charge-density-wave phase transition of ${\mathrm{TiSe}}_{2}$ using photoelectron spectroscopy with high angle and energy resolution. We accurately measured the band dispersions of the Se 4p and Ti 3d bands, whose interaction is thought to be deeply involved in the phase transition. In contrast to…
Depending on the dopant concentration, two distinct types of porous silicon can be formed during the anodization of silicon in hydrofluoric acid. A range of samples of both types of porous silicon has been investigated using x-ray double crystal diffraction techniques. The crystal lattice of porous silicon is found to…
Crystals of K 3 Fe(CN) 6 undergo a second-order phase transition accompanied by a soft mode at about 130 K. The crystal structures of the room- and low-temperature phases have been determined by X-ray diffraction. Crystals of the room-temperature phase are monoclinic with space group P 2 1 / c , a =7.058(1), b =10.426…
We report an analysis of new and previously existing optical absorption and fluorescence data, far-infrared data, and electronic Raman scattering data for Eu3+, Dy3+, and Er3+ in the C3i sites of Y2O3 and R2O3, where R=a rare earth. Our previous analysis of C2-site spectra yields an effective point-charge model for th…
The emission spectrum of Tb3+ substituted in YAG to various concentrations (x in Y3−xTbxAl5O12 ranges from 3×10−5 to 3×10−1) has been measured on samples prepared by two different methods. These methods are powder preparation by coprecipitation and growth of crystalline layers by liquid-phase epitaxy. The spectrum con…
The previously postulated production of holes during the electrical breakdown of varistors has been directly verified. In some compositions band-gap (3.2 eV) luminescence from the recombination of these holes with free electrons has been observed. The intensity of this luminescence is greater in varistor compositions…
We have performed an extended x-ray-absorption fine-structure (EXAFS) measurement of ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te solid solutions for various concentrations x in the single-phase range 0\ensuremath{\le}x\ensuremath{\le}0.7. Data have been collected on the Mn K, Cd…
The physical and electronic properties of poly(isothianaphthene) PITN, are reported, including initial characterization, electrochemical cyclic voltammetry, spectroscopy, and transport properties. PITN has the smallest energy gap of any known conjugated organic polymer, Eg≂1 eV. This novel conjugated polymer exhibits…
The light stabilization of polypropylene (PP) fibers places special requirements on the stabilization system due to the high surface to volume ratio, the severe processing conditions, and the post spinning treatments. Earlier systems provided only moderate performance lifetimes thus limiting the markets for PP fibers.…
The properties of hindered diazacycloalkanones were evaluated as light stabilizers and antioxidants for polypropylene. A totally hindered piperazinone was found to be excellent light stabilizer with many other desirable properties as a polymer additive. Partially hindered decahydroquinoxalinone derivatives were found…
Since their initial production by our laboratories about ten years ago, hindered amine light stabilizers (HALS) have become established as excellent light stabilizers of polymers. This review deals with their synthesis, evaluation and development.
Although polyethylene is essentially nonbiodegradable, it was found that copolymers of ethylene and 2-methylene-1,3-dioxepane prepared by a high pressure free radical solution polymerization were indeed biodegradable. Most synthetic polymers are not biodegradable because they have not been on the earth long enough to…
The absolute energy of the Lyman- alpha 1 line of hydrogen-like krypton has been measured with an accuracy of 36 p.p.m. The ions were produced at GANIL (Caen) and the X-rays emitted in flight detected with a flat crystal spectrometer. The (1s) Lamb shift of hydrogen-like krypton has been found to be 11.95+or-0.5 eV in…
Absolute elastic and inelastic differential cross sections for electrons scattered from methane and ethane have been measured for incident electron energies from 7.5 to 20 eV and scattering angles from 32 degrees to 142 degrees . The measurements were made using an electron spectrometer, incorporating hemispherical el…
The hindered amine story is an interesting success story involving participation by scientists throughout the world. The success of hindered amines has partly been due to the free exchange of information among scientists, so that the accomplishments of one group, studying stable free radicals, could be picked up by th…