Materials Literature
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A new spectroscopic technique for imaging the spatial distribution of nonradiative defects in semiconductor materials is presented. The technique combines the versatility and sensitivity of deep-level transient spectroscopy (DLTS) with the capability for defect analysis at high resolution of the scanning transmission…
The static magnetic susceptibility of single crystal MnTe 2 from 4.2 K up to 450 K was measured. The exchange constants J 1 and J 2 are estimated as -7.1 K and +1.3 K, respectively, using the high-temperature power series method. This set of J 1 and J 2 are consistent with the stability region for the 1-st kind AF ord…
We present a systematic Hamiltonian formulation and quantization of the massless spin-3/2 field theory using the Hamiltonian methods of Dirac and Faddeev.Received 25 February 1977DOI:https://doi.org/10.1103/PhysRevD.16.307©1977 American Physical Society
Ferroelastic behaviors have been found in Ca 2 Sr(C 2 H 5 CO 2 ) 6 . The tetragonal c axis of the crystal is rotated by angle 90° under appropriate external stress in the paraelectric phase. This axis rotation is always accompanied with the conversion of the sense of optical power. It is shown that these facts can be…
The band structure and the density of states of Zr${\mathrm{B}}_{2}$ have been calculated by an augmented-plane-wave method and compared with the observed x-ray photoelectron spectrum of valence band. The theoretical energy-distribution curve obtained by using the Kohn-Sham exchange potential was in good agreement wit…
Angular-resolved photoelectron spectra (ARPES) are presented for GeS using 21-eV excitation energy. From the measurements that cover a wide range of angles along the two principal directions in the basal plane of the orthorhombic layered compound GeS $E$ vs ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}}_{\ensurema…
A simple relationship similar to that reported by Mollwo and Ivey relating peak absorption energy to the lattice parameter in the alkali halides has been noted for several oxides of group-II and -III metals, including BeO, ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, Mg${\mathrm{Al}}_{2}$${\mathrm{O}}_{4}$, ${\mathrm{Y}}_{3…
Core-electron, valence-, and conduction-band spectra of the cubic sodium-tungsten bronzes ${\mathrm{Na}}_{x}\mathrm{W}{\mathrm{O}}_{3}$ have been obtained by x-ray photoelectron spectroscopy. The samples were vacuum-cleaved single crystals spanning the entire cubic composition range. The band spectra are consistent wi…
A microscopic model of charge-density waves in $2H\ensuremath{-}\mathrm{Ta}{\mathrm{Se}}_{2}$ at zero temperature is developed and applied to calculate the lattice dynamics in the commensurate phase. The results are compared with the Raman data of Holy et al. At finite temperatures the conventional microscopic approac…
X-ray photoelectron spectra (XPS) and $\mathrm{Al} K$ and $\mathrm{Al} {L}_{2,3}$ soft-x-ray spectra (SXS) of valence bands for aluminum-noble-metal alloys are rationalized on the basis that SXS spectra are dominated by dipole selection rules while XPS spectra chiefly reflect the noble-metal $d$ bands. We find, in agr…
We have used the triple-axis neutron-scattering technique to study $2H\ensuremath{-}\mathrm{Ta}{\mathrm{Se}}_{2}$ and $2H\ensuremath{-}\mathrm{Nb}{\mathrm{Se}}_{2}$ which undergo charge-density wave transitions at ${T}_{0}=122.3$ K and ${T}_{0}=33.5$ K, respectively. The transitions in both compounds appear to be seco…
We have investigated the influence of donor and acceptor substituents on the second and third order hyperpolarizabilities β and γ of large conjugated molecules such as stilbene and styrene derivatives. This was performed by two independent measurements of β and γ using the techniques of dc electric-field induced secon…
It is shown, using the dielectric matrix formalism, that in the presence of free carriers the rapidly changing component of the phonon potential (i.e. that due to short-range interactions) is not screened, but produces an additional slowly changing potential component. The resulting matrix element of the total phonon…
A powder neutron diffraction study of alpha -AgI has been carried out at several temperatures between 180 degrees C and 450 degrees C. The results do not support the widely quoted model for the distribution of silver ions originally proposed by Strock (1934-36) but instead indicate the silver ions are confined to the…
Reaction of monosubstituted epoxypropanes with benzylamine The reaction of the epoxides of the general formula magnified image with benzylamine at 40, 50 and 60°C has been examined. The determination of rate constants by variation of X has shown, that in the case of X = S or N no anchimeric acceleration occurred. Thes…
Abstract Ferroelectric bismuth oxides of the general formula (Bi2O2)2+(An-1BnO3n+1)2- (A = Ba, etc., B = Ti or other transition metal) have been examined by high-resolution lattice imaging electron microscopy. The lattice images show dark bands at the positions of the Bi20 2 layers, with n -1 lines between them due to…
The steady movement of a liquid meniscus in a circular capillary tube has been examined theoretically for dynamic contact angles close to 90° with minute slippage of the liquid on the solid, thus relaxing the conventional no-slip boundary condition. The resulting flow field does not produce an unbounded force at the c…
The thermal conductivity lambda , thermal diffusivity and heat capacity per unit volume has been measured for an epoxy resin, Araldite AW 106, with hardener HV 953 U. Measurements have been carried out at room temperature up to 2.5 GPa and between 300 and 430K at 0.11 and 0.27 GPa. The glass transition temperature and…
The creation probability of soliton-antisoliton pairs due to quantum-mechanical tunneling in the presence of an electric field in charge-density---wave condensates is calculated. This process gives rise to an additional electric conductivity strongly nonlinear in the electric field, which may account in part for the a…
Polyurethane rigid foam is widely used as a thermal insula tion material in low temperature service because of its low thermal conduc tivity. This paper describes the results of laboratory studies on various aspects of this application such as maintenance of insulation efficiency, corrosion protection, and friability.…