Materials Literature
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It is shown that the anomalous elastic behaviour of Invar alloys is due to the contribution f the exchange energy. Using a molecular field approximation the exchange contributions is given in terms of the first and second derivatives of the effectives fo the effective exchange integral J(r). These parameters are corre…
A new mechanism for sound absorption in disordered solids is proposed. The mechanism combines the following two effects: (i) A sound wave modulates the frequencies of the thermal phonons (phonons of frequency $\frac{\mathrm{kT}}{h}$). (ii) In a disordered solid, phonons are elastically scattered by the disorder. Becau…
Generalized x-ray scattering factors have been extended to include a 3d Slater-type atomic orbital. The new scattering functions include deformations that represent octapole and hexadecapole atomic charge distributions. These terms are suitable for charge density analysis of atoms with high site symmetry. For a reason…
Photoemission spectra for $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\le}11.7$ eV were measured from thin CsI films at 77\ifmmode^\circ\else\textdegree\fi{}K. The distribution of emitted electrons is interpreted in terms of optical excitation from a valence band comprising three branches of Bloch bands derived…
We report measurements of the magnetic susceptibility, Knight shift, and nuclear spin-lattice relaxation rates in the pure compounds Au${\mathrm{Ga}}_{2}$ and Au${\mathrm{In}}_{2}$ and an alloy of nominal composition ${\mathrm{Au}}_{0.95}$${\mathrm{Pd}}_{0.05}$${\mathrm{Ga}}_{2}$. Measurements were made in both the so…
The kinetics of energy transfer from antimony sensitizer to manganese activator in fluorophosphate phosphors has been studied. The transfer mechanism is identified as an exchange interaction by a comparison of the manganese concentration dependence of experimental quantum yield and emission decay curves with theoretic…
A novel electro-optic effect has been observed in thin homeotropic nematic layers. Electrodes, such as a pair of parallel lines, are located on a planar surface in contact with the liquid. Deformation of the homeotropic ordering occurs when the applied field exceeds a threshold strength. Induced optical birefringence…
The qualitative features of the bulk and surface energy bands of ionic transition-metal perovskite crystals such as SrTi${\mathrm{O}}_{3}$, BaTi${\mathrm{O}}_{3}$, KTa${\mathrm{O}}_{3}$, and BaZr${\mathrm{O}}_{3}$ are discussed. The linear-combination-of-atom orbitals (LCAO) method is used in combination with a genera…
We consider classical transition-state theory of collinear atom-diatom reactions. There are (many) potential surfaces for which this theory is exact provided all trajectories with energy above some fixed value are disregarded; the energy cutoff of course depends on the surface. We develop a simple criterion for recogn…
The dielectric relaxation study of glass-forming liquids show the presence of two relaxation regions at temperatures above TQ. The low frequency relaxation is attributed to the cooperative rearrangement of molecules. The high frequency relaxation, which continues to exist in the glassy state, is suggested to arise fro…
The point-multipole model, together with the Sawatzky model for overlap effects, has been used to calculate the electric field gradient tensors at the two nonequivalent ferric sites in Ca 2 Fe 2 O 5 . Good agreement with Mossbauer results has been obtained if alpha D and alpha Q , which have been considered as variabl…
Normal incidence reflectivity spectra using polarized light have been measured with E perpendicular to c as well as E//c for the layer type crystals of transition metal dichalcogenides WS 2 , WSe 2 , alpha -MoTe 2 , NbS 2 and NbSe 2 at 78 K and 300 K. Reflectivity peaks observed in the spectra of two polarizations are…
The magnetization of single crystals of Eu, Sm, Nd, Pr, and Pr-Nd alloys has been measured in fields up to 37 T (370 kG). The results give new information on the magnetic properties of these metals. Of particular interest is a first-order transition from a nonmagnetic to a metamagnetic phase in double-hexagonal close-…
A method is described for the direct measurement of the shear-alignment angle in a nematic liquid crystal. Results of such measurements are reported for the nematic phases of three compounds: PAA ($p$, ${p}^{\ensuremath{'}}$-azoxydianisole), MBBA ($p$-methoxybenzylidene-${p}^{\ensuremath{'}}\ensuremath{-}n$-butylanili…
An x-ray photoemission study of evaporated Al films has been performed in ultrahigh vacuum. The striking similarity of the valence-band spectrum with computed density of states allows a straightforward interpretation of the results. Core level spectra reveal structures which can be attributed to either inelastically s…
Abstract The behaviour of the ½a<111> screw dislocation core in the presence of an external shear stress on {110} planes has been studied for a variety of effective interionic potentials, each representing a stable b. c. c. lattice. The distortion and motion of the core are described using the concept of…
Phonon pulse propagation has been studied in fused silica at frequencies between 0.4 and 2.0 GHz for temperatures as low as 0.1 K. An increase in attenuation, observed as the incident acoustic intensity is decreased, is attributed to resonant scattering by two-level "tunneling states" intrinsic to glasses.
Reactivity and compatibility studies were carried out on some vanadium base alloys with ceramic fuel materials. The vanadium base alloys studied were V-20%Ti, V-15%Ti-7.5%Cr and V-5%Cr. The fuel materials with which these alloys were put in contact were UC, UN, (U, Ce)N and (U,Ce)(C,N). Experiments were carried out at…
Abstract Cotton sateen fabric was found to react with the 1 : 2 adduct of phosphorus trichloride and N,N‐dimethylformamide (DMF) in DMF or DMF—chloroform solutions at room temperature. During this reaction, the fabric acquired flame resistance. The introduction of as little as 1.2% phospohorus and 0.4% nitrogen, achie…
Silicone rubber rods covered by a polyester fiber mesh were implanted adjacent to either a femoral or carotid artery in 13 dogs. The rods were pulled out eight to ten weeks later and a segment of the carotid or femoral artery was excised and replaced by the newly formed tissue tube. Angiographic studies confirmed the…