Materials Literature
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Published information on the chemistry of oxygen compounds of iron — the ferrates(VI, V, IV) — has been reviewed briefly. The methods of preparation, chemical properties, thermal decomposition in air and in O2, the kinetics and mechanism of decomposition in solution, methods of analysis, structural, spectroscopic, and…
The adiabatic elastic constants of single crystals of neon at 24.3 K and of argon at 82.0 K have been determined by Brillouin scattering. For argon the values are ${C}_{11}=2.33\ifmmode\pm\else\textpm\fi{}0.08$, ${C}_{12}=1.49\ifmmode\pm\else\textpm\fi{}0.06$, ${C}_{44}=1.17\ifmmode\pm\else\textpm\fi{}0.07$, in units…
The magnetic structures of metallic samarium have been determined from neutron-diffraction data on a single crystal of $^{154}\mathrm{Sm}$. Anomalies in a number of physical properties of this metal at 106 and 13.8\ifmmode^\circ\else\textdegree\fi{}K are associated with ordering of the moments on the hexagonal and cub…
We report observation of bound-polaron hopping in pure NiO single crystals. The observed activation energy is $\ensuremath{\approx}0.7$ eV, the bandwidth $J\ensuremath{\approx}{10}^{\ensuremath{-}2}$ eV, and the binding center is suggested to be the ${\mathrm{Ni}}^{+2}$ vacancy.
The monoxides of the rare earth metals are currently receiving attention because of the possibility of their being ‘n’ or ‘p’ type semiconductors [6]. Unlike the R2O3 type sesquioxides whose structures and existence have been well established, very little details regarding the existence, structure, and defect substruc…
In the creep process a metal transition to the superconducting state is accompanied by a sharp increase in the strain rate. This increase however does not start simultaneously with the transition but in some time (relaxation time or delay time). Experiments proved this time to be strongly dependent on the temperature…
L'étude comparative des spectres de photoélectrons X de composés de cuivre I et II, ainsi que l'examen des modifications apparaissant au niveau des raies du cuivre et de l'oxygène dans les composés de cuivre I suite à l'action de gaz actifs (O2, H2O), indiquent que la structure satellite adjacente aux raies du cuivre…
The mechanism of microhardness print forming in diamond-structure crystals is considered to be the result of a local phase transition under the indenter with the formation of a metallic phase due to the high hydrostatic pressure generated in this case. It is shown that at the temperature T < 0.3 to 0.4 Tml, where the…
The crystal structure of caesium oxotetrafluorovanadate(V) has been solved and refined to an R-value of 0.070 using diffractometer measurements. The cell dimensions are: a = 548.4(2) pm, b = 634.2(2) pm, c = 1403.4(3) pm. The space group is Pnma (No. 62) with four formula units per cell. Each vanadium atom lies 32.6 p…
The thermal and electrical conductivities of six single crystals of tin with cadmium (cadmium content ranging from 0.24 to 0.97 at.%) have been measured from 4.2 to about 80 K. The lattice thermal conductivity was deduced for three of these samples of cadmium content in excess of 0.70 at.%, oriented close to 78\ifmmod…
A neutron diffraction study of L-lysine monohydrochloride dihydrate, C6H15N202. C1.2H20, has been carried out. The structure is monoclinic, space group P2~ with Z = 2. Cell parameters are: a = 7492 (1), b = 13.320 (4), c= 5.879 (1)/~, fl= 97.79 (1) ° [Wright & Marsh, Acta Cryst. (1962), 15, 54]. Least-squares refineme…
Electron paramagnetic resonance (EPR) studies of defect centers produced by x or γ irradiation of the hydrogen-bonded ferroelectrics KH2AsO4, KD2AsO4, RbH2AsO4, RbD2AsO4, and CsH2AsO4 and of the antiferroelectrics NH4H2AsO4 and ND4D2AsO4, are presented. The spectra, observed over 300–4.2°K, are characterized by a very…
Direct near-normal-incidence reflectance spectra were measured for MnO, CoO, and NiO between 3 and 27 eV at room temperature and below, and the corresponding dielectric response functions, $\ensuremath{\epsilon}={\ensuremath{\epsilon}}_{1}+i{\ensuremath{\epsilon}}_{2}$, were obtained by Kramers-Kronig inversion. Therm…
The infrared spectra of porphin and its metal complexes with 64Zn, 68Zn, Cu, and Ni have been obtained from 4000 to 100 cm−1. Normal coordinate analyses have been carried out on the D4h model of the porphin complexes with 64Zn, 68Zn, Cu, and Ni. Only the eighteen in-plane vibrations have been calculated. The results i…
We attempt to determine the binding energy and the wave function of the ground state of an electron that is attracted to the surface of an ionic crystal by its image potential and is repelled from the interior of the solid. For ionic crystals, such as LiF, the electrostatic theory is inadequate and the solid must be t…
A simple device for use with open shell SCF computations is proposed. This method eliminates the nonphysical elements in the usual method and leaves a simple operator which is easily computed or approximated.
A detailed experimental and theoretical study of the defect-induced far-infrared and first-order-Raman spectra of the NaCl: ${\mathrm{Ag}}^{+}$ system has been made. New low-temperature Raman data revealed many singularities pertaining to pure and perturbed phonons. Only a few of the singularities could be assigned to…
The first observation of surface-phonon-surface-plasmon coupling in small particles is reported. Thin layers of semiconducting CdO microcrystals with various free-carrier concentrations were used as samples. The coupling manifests itself in the infrared-absorption spectra through two absorption maxima corresponding to…
The cubic pyrochlores Cd 2 Nb 2 O 7 , Cd 2 Ta 2 O 7 , Sn 2 Nb 2 O 7 , Sn 2 Ta 2 O 7 . Cd 2 Sb 7 O 7 , Ca 2 Sb 2 O 7 , Mn 2 Sb 2 O 7 , Pb 2 Sb 2 O 7 , and related compounds were prepared and investigated by a number of methods. On heating above 700°. Ca 2 Sb 2 O 7 (pyrochlore) transformed to Ca 2 Sb 2 O 7 (weberite), w…
The crystal structure of trehalose dihydrate has been solved by direct methods and refined to an R index of 0-057 using anisotropic refinement. The space group is P212121 and four formula units of C12HzzOz~.2HzO are contained in the unit cell of dimensions a= 17.90, b= 12.21 and c= 7.586 A. The two glucopyranose resid…