Gypsum burning in one or several phases by suspension in a hot gas
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Crystallographic fast Fourier transforms
This paper presents methods for incorporating crystallographic symmetry properties into complex Fourier transforms in a form particularly well suited for use with the Cooley-Tukey fast Fourier transform algorithm. The crystallographic transforms are expressed in terms of a small number of one-dimensional special cases…
Solid State Electronic Devices
D V Morgan and M J Howes London: Wykeham Publications 1972 pp xii + 190 price £2·25 This book aims to give a qualitative understanding of the basic principles of operation of the most important solid state devices. It is written for first year undergraduate students and has the great merit of being readable and of hav…
Interband Magnetoreflection of ZnO
Abstract In magnetic fields up to 50 kOe and for photon energies greater than the band gaps for light polarized with E ⊥ c and E ‖ c oscillatory changes of reflectivity are observed on ZnO‐crystals at helium temperatures. The anisotropic reduced masses and hole masses and the energy gaps are deduced from the shift of…
Spectroscopic Properties of Organic Azo Compounds
Abstract Azo compounds are characterized by a low‐energy 1 (n,π * ) electronic state, which gives rise to a weak band at long wavelengths in the absorption spectrum. Coupling of this state with other low‐lying molecular states is responsible for the high intensity of the “azo band” compared to other forbidden transiti…
Metal-Insulator Transitions in Pure and DopedV2O3
The addition of ${\mathrm{Ti}}^{3+}$ and ${\mathrm{Mg}}^{2+}$ to ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ leads to the suppression of the antiferromagnetic insulating phase; whereas the addition of ${\mathrm{Ti}}^{4+}$, ${\mathrm{Zr}}^{4+}$, and ${\mathrm{Fe}}^{3+}$ results in a first-order transition from a metallic to a…
Optical Constants of Water in the 200-nm to 200-μm Wavelength Region
Extinction coefficients k(lambda) for water at 25 degrees C were determined through a broad spectral region by manually smoothing a point by point graph of k(lambda) vs wavelength lambda that was plotted for data obtained from a review of the scientific literature on the optical constants of water. Absorption bands re…
Antiferroelectricity among compounds with spinel structure?
Recent re-evaluation of diffraction data from cubic spinel compounds has suggested that in many cases the crystal structure is properly referred to the noncentrosymmetrical space group F43m. This symmetry provides the possibility of antiferroelectric behaviour which may resolve previous theoretical difficulties concer…
Exhaust Catalysts: Appropriate Conditions for Comparing Platinum and Base Metal
There are fundamental differences in the behavior of alumina-supported samples of a platinum and a copper-chromium catalyst for oxidation of carbon monoxide in a simulated automotive exhaust stream. Ignoring such differences can result in inappropriate comparisons between oxidation catalysts for automotive application.
Magnetic exchange energy contribution to the elastic constants and its relation to the anomalous elastic behaviour of invar alloys
It is shown that the anomalous elastic behaviour of Invar alloys is due to the contribution f the exchange energy. Using a molecular field approximation the exchange contributions is given in terms of the first and second derivatives of the effectives fo the effective exchange integral J(r). These parameters are corre…
Contribution to Sound Absorption in Disordered Solids at Low Temperatures
A new mechanism for sound absorption in disordered solids is proposed. The mechanism combines the following two effects: (i) A sound wave modulates the frequencies of the thermal phonons (phonons of frequency $\frac{\mathrm{kT}}{h}$). (ii) In a disordered solid, phonons are elastically scattered by the disorder. Becau…
Electron population analysis with generalized x-ray scattering factors: Higher multipoles
Generalized x-ray scattering factors have been extended to include a 3d Slater-type atomic orbital. The new scattering functions include deformations that represent octapole and hexadecapole atomic charge distributions. These terms are suitable for charge density analysis of atoms with high site symmetry. For a reason…
Photoemission from CsI: Experiment
Photoemission spectra for $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\le}11.7$ eV were measured from thin CsI films at 77\ifmmode^\circ\else\textdegree\fi{}K. The distribution of emitted electrons is interpreted in terms of optical excitation from a valence band comprising three branches of Bloch bands derived…
Nuclear Magnetic Resonance, Magnetic Susceptibility, and Lattice Constants of Solid and Liquid AuGa2,Au0.95Pd0.05Ga2, and AuIn2
We report measurements of the magnetic susceptibility, Knight shift, and nuclear spin-lattice relaxation rates in the pure compounds Au${\mathrm{Ga}}_{2}$ and Au${\mathrm{In}}_{2}$ and an alloy of nominal composition ${\mathrm{Au}}_{0.95}$${\mathrm{Pd}}_{0.05}$${\mathrm{Ga}}_{2}$. Measurements were made in both the so…
Energy Transfer between Antimony and Manganese in the Fluorophosphate Phosphors
The kinetics of energy transfer from antimony sensitizer to manganese activator in fluorophosphate phosphors has been studied. The transfer mechanism is identified as an exchange interaction by a comparison of the manganese concentration dependence of experimental quantum yield and emission decay curves with theoretic…
Transverse field effects in nematic liquid crystals
A novel electro-optic effect has been observed in thin homeotropic nematic layers. Electrodes, such as a pair of parallel lines, are located on a planar surface in contact with the liquid. Deformation of the homeotropic ordering occurs when the applied field exceeds a threshold strength. Induced optical birefringence…
d-Band Surface States on Transition-Metal Perovskite Crystals: I. Qualitative Features and Application to SrTiO3
The qualitative features of the bulk and surface energy bands of ionic transition-metal perovskite crystals such as SrTi${\mathrm{O}}_{3}$, BaTi${\mathrm{O}}_{3}$, KTa${\mathrm{O}}_{3}$, and BaZr${\mathrm{O}}_{3}$ are discussed. The linear-combination-of-atom orbitals (LCAO) method is used in combination with a genera…
On transition-state theory and the classical mechanics of collinear collisions
We consider classical transition-state theory of collinear atom-diatom reactions. There are (many) potential surfaces for which this theory is exact provided all trajectories with energy above some fixed value are disregarded; the energy cutoff of course depends on the surface. We develop a simple criterion for recogn…
Intrinsic mobility of molecular glasses
The dielectric relaxation study of glass-forming liquids show the presence of two relaxation regions at temperatures above TQ. The low frequency relaxation is attributed to the cooperative rearrangement of molecules. The high frequency relaxation, which continues to exist in the glassy state, is suggested to arise fro…
Electric field gradient calculations in dicalcium ferrite
The point-multipole model, together with the Sawatzky model for overlap effects, has been used to calculate the electric field gradient tensors at the two nonequivalent ferric sites in Ca 2 Fe 2 O 5 . Good agreement with Mossbauer results has been obtained if alpha D and alpha Q , which have been considered as variabl…