Materials Literature
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Using a model cubic anharmonic crystal potential and Fermi's golden rule, an expression for the anharmonic relaxation time for a nonequilibrium long-wavelength LO phonon is rigorously derived. Decay times for various bulk, alloy, and quantum-well semiconductor systems are calculated. Comparison with time-resolved Rama…
A systematic investigation of electron spin resonance (ESR) properties, the spin susceptibility (χ spin ), peak-to-peak linewidth (Δ H pp ) and g -value, of κ-type BEDT-TTF superconductors has been carried out in order to clarify their electronic structures in the normal state. κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br (Space gro…
The viewing angle, contrast ratio, and response time of a negative birefringent film-compensated homeotropic liquid-crystal cell were evaluated. A spin-coated polyimide film was found to cancel the phase retardation of the liquid-crystal cell over a wide range of incident angle. Such a film-compensated homeotropic liq…
Excitonic properties have been studied in cubic ${\mathrm{Zn}}_{0.42}$${\mathrm{Cd}}_{0.58}$S lattice matched to GaAs. At 2 K, the time-integrated photoluminescence spectrum was composed of single emission peaking at 2.863 eV and its LO-phonon replica. The linewidth of the main peak was 18.5 meV, which fairly well agr…
Abstract The effect of presence of water on the transport of oxygen through films of Nylon‐6 was evaluated at 5, 23, and 40°C by permeation experiments. Through the oxygen permeability experiments it was found that the diffusion of oxygen through Nylon‐6 is not a simple Fickian process and the total diffusion process…
High-temperature phase relations in the Fe-rich corner of the Nd-Fe-Ti ternary alloy system have been investigated and an equilibrium phase diagram has been constructed at 1100 °C. Arc-melted and annealed alloys of systematically varying compositions were characterized utilizing scanning electron microscopy, an energy…
Time dependence of intensity of magnetization is the result of thermal activation of metastable domain processes. The simple (M,H) representation of magnetic behavior may be extended to include time dependent effects using a constitutive equation. Magnetic processes may be described by the movement of a point over a t…
A structural model for intermediate-size silicon clusters is proposed that is able to generate unique structures without any dangling bonds. This structural model consists of a bulklike core of five atoms surrounded by a fullerenelike surface. Reconstruction of the ideal fullerene geometry results in the formation of…
The metastable α″-Fe16N2 phase may have a magnetic moment up to 50% higher than that of pure bulk α-Fe. This article addresses the following issues. (i) Can epitaxial films of α″-Fe16N2 be prepared phase pure? Yes, but there are some doubts. (ii) Can powders of α″-Fe16N2 be prepared phase pure? Not yet. (iii) Is the M…
Experimental data on the thermoelectric coefficients of a very-low-mobility (\ensuremath{\mu}=0.13 ${\mathrm{m}}^{2}$/V s) two-dimensional electron gas in a GaAs/${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$As quantum well are presented. The measurements span a temperature range of 1…
The development of a number of models of slow relaxation in magnetic materials is reviewed. A phenomenological theory based on the intrinsic energy barrier is shown to explain the form of time dependence of the magnetization, including the logarithmic time dependence observed for systems with a relatively wide distrib…
It is reported that Nd-Fe-B magnetic powders prepared by utilizing the HDDR (hydrogenation, disproportionation, desorption, and recombination) phenomena exhibit high coercivity, and the addition of Co, Ga, and Zr induces magnetic anisotropy in these powders. HDDR phenomena are caused by the heat treatment in hydrogen…
We report on the magnetic properties of the Cr-based diluted magnetic semiconductors ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Cr}}_{\mathit{x}}$Se and ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Cr}}_{\mathit{x}}$S (x0.01). The specific heat was measured in the temperature range…
The plane-wave pseudopotential (PWPP) method is used to perform density-functional-theory (DFT) calculations for two grain boundaries in aluminum studied previously using the embedded-atom method (EAM) and high-resolution transmission electron microscopy: (1) a \ensuremath{\Sigma}=11 (11\ifmmode\bar\else\textasciimacr…
The formation of polarons and bipolarons in conjugated polymers with nondegenerate ground states is studied theoretically. We use the Pariser-Parr-Pople model combined with the Su-Schrieffer-Heeger model of electron-lattice coupling and a Brazovskii-Kirova-type symmetry-breaking interaction. The relative stability of…
We report the formation of several members of the recently discovered class of R3(Fe,T)29 compounds and some of their intrinsic properties. Focusing on materials with T=Ti and Cr, we have prepared R3(Fe,Ti)29 (R=Ce, Pr, Nd, Sm) and R3(Fe,Cr)29 (R=Ce, Nd, Sm) compounds which all feature the novel monoclinic crystal str…
Extremely well resolved Si 2p core-level spectra from the clean Si(111)7\ifmmode\times\else\texttimes\fi{}7 surface have been obtained at \ensuremath{\sim}100 K. Surface-shifted components become visible to the naked eye. Contributions from the constitutive entities of the complex 7\ifmmode\times\else\texttimes\fi{}7…
A large intrinsic magnetoresistance has been found near the ferromagnetic transition of metallic manganese oxides with perovskite-type crystal structure. The magnetic and transport properties were measured on bulk and thin-film La1−xAxMnO3+δ with A=Ca,Sr,Ba. Assuming the double-exchange model proposed by Zener [Phys.…
Upon irradiating poly(p-phenylene vinylene) thin films with white light in air (total exposure \ensuremath{\sim}5 J/${\mathrm{cm}}^{2}$), an enhancement of about forty times in photocarrier generation and a similar reduction in the photoluminescence intensity are observed. The wavelength and electric-field dependence…
New rare-earth (R), iron-rich ternary intermetallic compounds of the form R3(Fe,M)29 with the monoclinic Nd3(Fe,Ti)29 structure (space group P21/c, ♯14, Z=2) have recently been shown to form with R=Ce, Nd, Pr, Sm, and Gd, and M=Ti, V, Cr, and Mn. This novel structure is derived from the alternate stacking of Th2Zn17 a…