Materials Literature
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The variation with composition of the electronic structure of polycrystalline sodium tungsten bronzes Na x WO 3 (0<x<1) has been studied using a combination of high-resolution electron spectroscopic techniques. Samples on either side of the metal-nonmetal transition (x approximately 0.25 from conductivity data)…
For pt.I see ibid., vol.16, p.6129 (1983). Proton second moment, T 1 H .T 1 rho H and T 1 11B measurements over the temperature range 330K>T>46K are reported. At low temperatures tunnelling of the protons of the NH 3 group influences the second moment and T 1 rho H results seriously. An analysis of the results h…
The results of an X-ray diffraction investigation of powdered H 3 N.BH 3 are reported. A first-order rotational order-disorder phase transition has been observed at 225K. In the high-temperature tetragonal phase the space group permits twelvefold reorientations of GH 3 and NH 3 groups. The cell parameters are linear f…
For the amorphous alloy of nominal composition Co53Fe5Ni10Si11B16 magnetic properties such as the anisotropy energy, the initial susceptibility, the coercive field, and the remanent magnetization are investigated at room temperatue as functins of an applied tensile stress. From an analysis of the magnetization process…
The heat capacity (C), lattice constant (a), density (d), and electrical conductivity (σ) of RE monosulphides LnSx (Ln = La, Pr, Nd, and Gd) are studied in the homogeneity range (up to x = 0.80). A vacuum adiabatic calorimeter is used to measure C between 2 and 300 K. A systematic analysis of the experimental densitie…
It is shown in this work that the room-temperature excitation spectra of as-grown crystals of LiF, NaF, NaCl, KCl, and KBr doped with ${\mathrm{Mn}}^{2+}$ reveal the existence of double excitation peaks. These peaks are related to the formation of precipitated phases containing ${\mathrm{Mn}}^{2+}$ in the alkali halid…
Arsenic-doped triglycine sulfate single crystals show an enhancement in pyroelectric coefficients and the pyroelectric figures of merit p/K and p/√K by a factor of 2.2 over those of pure triglycine sulfate single crystals at the most desirable operating temperature of the pyroelectric sensors, ≂25 °C. The crystals are…
Thermoelectric power measurements on a group of tetramethyltetrathiafulvalene ${(\mathrm{TMTTF})}_{2}X$ salts show a wide variety of behavior. In the range of temperatures $300\ensuremath{\ge}T\ensuremath{\gtrsim}100$ K several of the salts ($X=\mathrm{B}{\mathrm{F}}_{4}, \mathrm{Cl}{\mathrm{O}}_{4}, \mathrm{N}{\mathr…
The central-force network dynamics model for glasses is extended to treat networks involving small regular rings of bonds. In particular, band-limit formulas are obtained for an ${A}_{2}{X}_{3}$ glass consisting of regular puckered six-membered ${A}_{3}{X}_{3}$ rings. The special case of planar rings is compared with…
The vortex–electrohydrodynamic instability occurring in thin freely suspended layers of some nematic liquid crystals is investigated. The vortex pattern is observed both in the anisotropic and in the isotropic phase of the nematic liquid crystal. In this paper, we study the behavior of the vortex pattern when dc and a…
Electrical resistivity measurements are reported for a variety of ${({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x})}_{2}{\mathrm{O}}_{3}$ and ${\mathrm{V}}_{2(1\ensuremath{-}y)}{\mathrm{O}}_{3}$ systems, with $0\ensuremath{\le}x<0.06$ and $0\ensuremath{\le}y<0.01$, in the range 20-300 K. The metal---antiferro…
The optical transmittance spectra of polypyrrole perchlorate have been measured at various stages in the reduction to neutral polypyrrole at 300 and 120 K and at high pressure. Analysis of the results suggests that the polypyrrole chain is composed of conjugated segments of various lengths. The optical conductivity sp…
The dynamical process of the diffusion of tagged particles in a one-dimensional concentrated lattice gas is investigated. The particles are noninteracting except that double occupancy is forbidden. The mean-square displacement of a tagged particle is calculated for all times by an approximate theory and compared to re…
A recently developed method, which uses piezoelectrically generated pressure steps for the determination of electric-field profiles in dielectrics, has been applied to electron-beam-charged polyfluoroethylenepropylene (FEP) and polyethyleneterephthalate (PETP) electrets. The results indicate that the technique can be…
A thin film quasiadiabatic calorimeter has been applied to the measurement of the stopping power for electrons, under conditions of small angle scattering, in Al, Ni, Cu, Ag and Au in the energy region 1 keV to 10 keV. Results are presented with an estimated precision of 15%. Corrections are included for the multiple…
The detection of appreciable concentrations of ferric iron in a synthetic green glass equilibrated at an oxygen fugacity of 10 −11 atm prompted a Mossbauer spectral study of pristine emerald‐green glass spherules carefully handpicked from regolith sample 15426. No Fe 3+ ions were detected in this lunar sample or in a…
The crystal and magnetic structure of Rb 2 CrCl 4 , a compound that exhibits two-dimensional ferromagnetism with nearly easy-plane behaviour, has been investigated using single-crystal neutron diffraction at 5.5, 77 and 300K. Selected Bragg reflections have also been examined at temperatures up to 573K. At all tempera…
A free energy formulation of localised canting in substituted magnetic oxides is described. In contrast with earlier attempts at mathematical formulations of localised canting, quantities which may be replaced by average values and those which must be considered on a site-to-site statistical basis are clearly delineat…
Optical reflectivity and magneto-optical polar Kerr effect measurements in the photon energy ranges from 0.006 to 12 eV and 0.5 to 5 eV, respectively, are reported for magnetite and for Li and Mg ferrites. The diagonal and off-diagonal elements of the dielectric tensor are derived. From a comparison of the experimenta…
The electronic structure of Mo and Mo oxides has been studied using ultraviolet and X-ray photoelectron spectroscopy. The valence band spectrum of Mo(100) is compared with calculations of the density of states (DOS). A fairly good agreement of the characteristic peak positions with the DOS maxima is obtained. The Mo 3…