Materials Literature
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Data concerning the thermal decomposition of lanthanide, yttrium, and scandium oxalates and carbonates are surveyed. The complexity of the process, the large number of stages involved, and the dependence of the composition of the intermediates in the thermal transformations on the experimental conditions is noted. Cer…
The authors investigate the temperature renormalisation of the magnetic excitations in FeCl 2 , where, owing to the low value of the spin, a careful treatment of its large anisotropic effects appears to be necessary. A self-consistent renormalised theory which is not affected by kinematic inconsistencies is presented…
We report the microwave conductivity of a single crystal of the superionic conductor hollandite (${\mathrm{K}}_{1.54}$${\mathrm{Mg}}_{0.77}$${\mathrm{Ti}}_{7.23}$${\mathrm{O}}_{16}$). The charge carriers are potassium ions which propagate along channels. Transport is determined by thermally activated hopping of the po…
The melting behaviour for finite size clusters is calculated in the framework of positional disorder theory. It is shown that the 'melting anomalies' observed in a variety of absorbate systems, such as H 2 O in porous Al 2 O and N 2 or Ar on TiO 2 , are consistent with the melting characteristics of small clusters. In…
X-ray photoelectron spectra of Ag, O, and Cs and quantum yield distributions from surfaces prepared by evaporating Cs onto Ag oxidized in ultrahigh vacuum have been measured. The structure of this surface determined from these measurements consists of silver particles dispersed in a matrix of ${\mathrm{Cs}}_{2}$O with…
Abstract A formal derivation of the sink strengths to be used in point defect rate theory is presented. Previous models that have been invoked for the approximate evaluation of these parameters are discussed. It is shown that the effective medium approach, as introduced earlier by us, constitutes the best available ap…
The magnetic and crystallographic nature of the compounds NiMn1−tTitGe (0 ≦ t ≦ 1) are studied by X-ray and neutron diffraction and magnetometric measurements. It is shown that the solid solutions arise for 0 ≦ t ≦ 1, with the crystal structure of the NiTiSi type. A magnetic phase diagram is constructed: for 0 ≦ t ≦ 0…
A theory of the fractional glow technique (FGT) for an arbitrary heating regime and first-order recombination kinetics is developed. In order to describe a trap distribution function (TDF) its characteristics: (i) the mean activation energy, (ii) the mean frequency factor, (iii) the recombination intensity, (iv) the F…
An experimental and theoretical investigation of the electronic structure of a ternary semiconductor, ${\mathrm{Tl}}_{3}$As${\mathrm{Se}}_{3}$, is reported. The total valence-band density of states has been measured by x-ray photoelectron spectroscopy (XPS). A simple prescription, utilizing atomic term values, is sugg…
The self-consistent-phonon (SCP) formalism has proved valuable in calculating the anharmonic contributions to lattice-dynamic properties. It is a numerical iterative procedure for obtaining the equation of state and other thermodynamic functions. Replacing the sums over frequencies in the SCP formalism by appropriate…
Dispersion relations are obtained by two different methods for surface plasmons (in the nonretarded limit) propagating on the surface of a dielectric medium on which a large-amplitude grating has been ruled. The first method is based on the Rayleigh hypothesis; the second method is based on the extinction-theorem form…
The saturation magnetization per Mn atom P s at 4.2 K was obtained with a relation P s =3.8 y µ B for y c < y <0.35 and P s =2.8 y µ B for y < y c in Mn 0.5 V 0.5- y Al y . Here y c ≈0.2 which corresponds to the concentration at the boundary between B2 and L2 1 (Heusler) structures. The 55 Mn NMR frequency at 4.2 K al…
The infrared reflectivity and transmission on the quasi-one-dimensional structure Hf${\mathrm{S}}_{3}$ of light with polarizations both parallel and perpendicular to the chains are measured. They are compared with the frequencies already observed in Raman scattering indicating that the interchain coupling is very weak.
Polarized Raman spectra of ZnCl2 were obtained in the liquid phase near the melting point (T = 598 K), and in the glassy phase (T = 293 K). Measurements were performed down to a very low frequency shift (2 cm−1) from the exciting line. Our analysis of the Raman data provides an interpretation of the collision-like con…
Optical absorption and emission spectra are reported for the cubic Cs2NaHoCl6 elpasolite system. Detailed energy and intensity analyses of the high-resolution, variable-temperature spectra allow characterization of the crystal field energy level structure associated with eleven of the Ho3+ term levels. The term levels…
Anomalous thermal expansion of FeNi alloy is calculated on the basis of Liberman-Pettifor's virial theorem and the full single site approximation in the functional integral method. Results explain well the Invar effect. In general, the electronic contribution to the thermal expansion consists of three terms, i.e. the…
Angle-resolved photoelectron spectroscopy coupled with the polarized continuum of synchrotron radiation has been used to identify unambiguously a large enhancement in the photoexcitation from A(100) due to the surface photoeffect. This large enhancement in the cross section occurs only when the excitation field has a…
A theory for the coexistence problem of the spin density wave (SDW) and superconductivity (SC) in highly anisotropic materials is presented. On the basis of a simplified electronic band model a Hartree-Fock approximation is applied. It is concluded that the SDW state is precluded when the SC state developes at a highe…
The dielectric and elastic properties of cyano-substituted nematic liquid crystals are investigated. The results are discussed in terms of molecular properties and molecular association.
Electron spin resonance signals due to isolated Zn vacancies decreased in intensity and new signals ( A 1 and A 2 ) increased as electron-irradiated ZnS containing Cl impurity was kept at room temperature. The features of the new signals are as follows: For the A 1 signal g // =2.0545 and g ⊥ =2.0264, where g // is ta…