Materials Literature
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The electrical conductivity and thermoelectric power of the superionic conductor Ag 3 SBr were measured in the temperature range from 293 K to 493 K. Considerable deviations from the Arrhenius law was observed in the results of the ionic conductivity. The temperature dependence of the thermoelectric power of this syst…
57 Fe and 19 Sn Mossbauer investigations of the antiferromagnetic compound FeSn are reported from 77K to well above its magnetic transition temperature. The observation of a single nuclear Zeeman pattern from 1(a) Sn sites implies that the spin ordering in the basal plane is collinear. The 57 Fe Mossbauer studies show…
A pattern of driven vortices can be observed in the shear layer created in a fluid by a rotation movement. We present such an experiment where a liquid membrane is used to close a thin experimental volume of air thus forming a wall with the following properties : — The parallel component of the fluid velocity does not…
Abstract The dependence of the first order Raman scattering efficiency of CaF 2 , SrF 2 , BaF 2 and diamond on photon energy ω L has been measured with different techniques. We find that in the visible these cross‐sections increase with ω L much faster than ω . This result has important implications as CaF 2 , for ins…
Abstract The stage dependences of the Raman spectra of potassium, rubidium and cesium graphite intercalation compounds are reported. The spectra of each set of compounds are found to be qualitatively and quantitatively consistent with the ‘nearest layer’ model for the carbon intralayer E vibrations of intercalation co…
It is shown theoretically that the superconducting state coexisting with charge-density wave (CDW, its wave vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{Q}}$) is characterized by the spatially varying periodic order parameter $\ensuremath{\Delta}(Q)$ in addition to the ordinary uniform order parameter $\ensurem…
Polished polycrystalline specimens of Si, Sic, and Si 3 N 4 were heated to high temperatures and the rate of thermal etching was measured. Grain‐boundary grooving occurred on silicon by surface diffusion, with a surface‐diffusion coefficient given by image Silicon carbide surfaces became extremely rough and very littl…
The reaction of [Au8L8](NO3)2(L = PPh3) with the phosphine scavenger [RhCl(C8H14)2]2 yields [Au8L7]-(NO3)2, X-ray analysis of which reveals the Au skeleton to be a fragment of the centred icosahedron; the cluster to be a fragment; the cluster is an intermediate in the reactions of [Au9L8]3+, and its 197 Au Mössbauer s…
The oxidative cleavage of disulphide bonds to form the sulphonic acid derivatives is shown to be an important reaction of AuX4–(X = Cl, Br) with proteins and peptides; the implications of this reaction for the toxicity of gold compounds are discussed.
Adsorption isotherms and i.r. spectra of CO2 on the perovskite-type oxide LaCoCO3 are given. Coverages at 50 mmHg are above half a monolayer. At 195 K the B.E.T. multilayer adsorption isotherm fits the data satisfactorily while at 623–673 K the Freundlich isotherm is obeyed. At lower temperatures (195–373 K) mainly ph…
A single-crystal X-ray structural investigation of the material previously known as ‘Ag2O II’ has shown the correct empirical formula to be Ag3O.
Surface oxidation of La, Ce, Sm and Tb metals has been investigated by He(II) ultraviolet photoelectron spectroscopy (u.p.s.) and X-ray photoelectron spectroscopy (X.p.s.). Oxidation of La gives rise to La2O3 on the surface. While Ce2O3 appears to be the stable oxide on the surface, we find evidence for formation of C…
Dielectric permittivities were measured on compounds having different smectic phases in broad temperature intervals. Both the parallel and the perpendicular component of permittivity are given and the variationsare interpreted. The intensity of the low frequency dielectric dispersion is interpreted by Bordewijk's form…
Abstract The high temperature modifications β -SnS and β -SnSe crystallize in the orthorhombic TlI-type structure [ Cmcm , No. 63; SnS at 905 K: a = 4.148(2), b = 11.480(5), c = 4.177(2) Å; SnSe at 825 K: a = 4.410(6), b = 11.705(7), c = 4.318(4) Å]. For the λ -type phase transition α → β from the GeS-type (B16) to th…
Various parts of several plants were tested for their performance in protecting steel and aluminium against corrosion under immersed conditions. Argemone mexicana, calotropis procera, carrot and garlic were found to be good inhibitors for steel in neutral media, while tobacco, black pepper, castor seed, acacia gum and…
Sulfide corrosion cracking of linepipe steel was studied from metallurgical and environmental standpoints using laboratory and full size tests. Sulfide corrosion cracking can be classified into hydrogen induced cracking (HIC) and sulfide stress cracking (SSC). HIC initiates at an elongated inclusion and tends to propa…
In the past ten years there have been significant advances in the theoretical and experimental analysis of high-voltage gas breakdown and surface flashover of insulators in compressed gases. This has probably been fostered by the recent growth in the design and application of gas-insulated high-voltage equipment. The…
abundance and water vapor partial pressure on refractivity have been combined into a simplified equation for the refractivity of air, and estimates have been made of uncertainties in calculated refractivity. Under ambient conditions typical of metrology laboratories, the agreement between the simplified equation and E…
It is found theoretically and experimentally that a linear relationship between capacitance and reciprocal voltage of a nematic liquid crystal cell of homogeneous alignment. From this slope, the ratio of elastic constants K33/K11 can be acculatly obtained.
The general features of the a-c impedance at a metal-electrolyte interface as a function of frequency are depicted, and recently developed measurement techniques are described. It is established that at low and very low frequencies, down to the millihertz domain, relaxation phenomena are found in those cases where the…