Materials Literature
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Energy band structures of Gd-pnictides, GdX(X=N, P, As and Sb), known to show a transition from a semiconductor to a metal in the series from GdN to GdSb, are calculated using the APW method. It is found that the energy bands depend sensitively on a choice of the one-electron potential. Then, the calculation is carrie…
Abstract Infrared spectroscopy was used for the quantitative determination of the degree of crystallinity of semicrystalline crosslinked polymeric films with particular application to the characterization of poly(vinyl alcohol) (PVA) networks. The intensity of the 1141 cm −1 band of the IR spectrum of PVA is sensitive…
The experimental evidence for heat transport by magnons in magnetic insulators is reviewed. It is noted that in a thermally isolated system, the magnon temperature comes to equilibrium with the phonon temperature with a finite relaxation time ${\ensuremath{\tau}}_{\mathrm{mp}}$. Since a conventional thermal-conductivi…
The Rietveld profile-analysis refinement procedure [Rietveld, J. Appl. Cryst. (1969), 2 , 65–71] is here applied to microdensitometer-measured Guinier–Hägg X-ray powder film data (strictly monochromated Cu K α 1 radiation). Various functions for describing the profile form of an individual reflection are tested; the m…
Free radical-initiated copolymerization of N-phenyl maleimide (NPMI) with styrene (St), vinyl acetate (VAc) and methyl meth-acrylate (MMA) at 35°C in benzene solution initiated by AIBN was studied. The copolymerization of NPMI and St yields a “nearly equimolecular” alternating copolymer, irrespective of monomer feed.…
A simple model for a nematic liquid crystal is presented, in which the short-range intermolecular repulsions are represented by repulsions between hard spherocylinders, and the (anisotropic) intermolecular attractions are treated self-consistently in the mean field approximation. Using scaled particle theory, an expre…
A survey of the literature on the subject of treeing in solid dielectrics is presented. The purpose is to provide an introduction to the subject, some background for the current research work, and a list of references to some of the more rigorous treatments which in most cases have a narrower scope. The trees which gr…
It is well known that space charge accumulation has a great influence on both the short-time and long-time breakdown strengths of plastic insulation systems operating under direct voltages. In this paper, dc treeing phenomena initiated from the tip of a needle electrode inserted into a polyethylene specimen have been…
Abstract The electrical conductivity and Hall coefficient perpendicular to the c ‐axis of hexagonal MoS 2 , MoSe 2 , and WSe 2 are measured over the temperature ranges 120 to 1170 K and 140 to 820 K, respectively. The derived temperature‐dependent carrier densities are described by n ∼ exp ( –E/kT ) for temperatures l…
Abstract Hydrotalcite-like compounds [Mg I − x Al x (OH) 2 ] x + [A 2− x /2 , m H 2 O] x − , where A 2− is SO 4 2− or CrO 4 2− and x ≇ 0.25, were prepared by a coprecipitation method and their physico-chemical properties were studied by X-ray diffraction, thermal analysis, i.r. absorption spectra and acidity-basicity…
A computer program has been written with the aim of calculating powder patterns without the use of crystallographic tables. This has been achieved by deriving all symmetry information such as general equivalent positions from the Hermann-Mauguin space-group symbols, by calculating automatically the multiplicities of s…
A review is given of the nonlinear optical properties of 20 uniaxial crystals: KDP, DKDP, ADP, CDA, DCDA, RDA, RDP, LiIO 3 , LiNbO 3 , Ag 3 AsS 3 , Ag 3 SbS 3 , AgGaS 2 , AgGaSe 2 , ZnGeP 2 , CdGeAs 2 , GaSe, CdSe, HgS, Se, Te. Typical applications of these crystals are indicated.
The thermal conductivity, kappa , has been measured as a function of temperature between 2K and 100K of polycarbonate (PC), polyvinyl chloride (PVC) isotactic polypropylene (PP), polyoxymethylene (POM), and polyethylene terephthalate (PET). For the latter three systems the variation of kappa on extrusion has also been…
Transient nuclear magnetic resonance (NMR) measurements on 3He, generated by β decay and contained in aging titanium tritide (TiH1.8), have been carried out. The experiments were conducted over a period of about three years during which the rate of helium evolution from the sample abruptly increases. Qualitative analy…
Multiple-order Raman scattering was observed in CsI doped with Mn$\mathrm{O}_{4}^{}{}_{}{}^{2\ensuremath{-}}$. The Raman spectra consist of a series of sharp, equally spaced lines due to multiple-order scattering from the totally symmetric mode of Mn$\mathrm{O}_{4}^{}{}_{}{}^{2\ensuremath{-}}$. Each sharp line in the…
Generalized susceptibilities, ${\ensuremath{\chi}}^{0}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}})$, have been obtained for the $1T$ polymorphs of both Ta${\mathrm{S}}_{2}$ and Ta${\mathrm{Se}}_{2}$ from their Korringa-Kohn-Rostoker band structures. Peaks are found which correspond to the charge-density-wave (CDW…
From Knudsen effusion mass spectrometric examination of reactions of the type M(g)+MO(g) =M2O(g), 2MO(g) =M2O2(g), and 2MO(g) =MO2(g)+M(g), the atomization energies ΔH°0 (kcal/mole) of the following new species have been estimated: Eu2O(g), 174±12; Gd2O(g), 236±10; Tb2O(g), 243±12; Ho2O(g), 216±14; Lu2O(g), 266±14; Eu…
The heat capacity of $\ensuremath{\beta}$-alumina containing Li, Na, K, Rb, and Ag as the diffusing ion is found to be a strong function of the ion at temperatures between 1.3 and 40 K. The excess heat capacity above a Debye contribution for the host lattice of Al and O ions is compatible with the low-frequency modes…
In ionic charge-transfer salts which have segregated stacks of organic donor ($D$) and acceptor ($A$) molecules, the major feature of the classical electrostatic interactions is the strong repulsion between like charges along the stacks. Two ways are described by which the magnitude of this repulsion may be decreased:…
Electron drift mobilities have been observed in ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ crystals along the molecular direction by transient photoconductivity techniques. The mobility is 1.0 ${\mathrm{cm}}^{2}$/V sec, independent of temperature from 207 to 465 K. This result is consistent with a trend among inorganic and…