Dissolution kinetics of calcium carbonate in sea water; IV, Theory of calcite dissolution
RELATIVE EFFICIENCY OF CARBONATE DISSOLUTION AND PRECIPITATION DURING DIAGENESIS: A PROGRESS REPORT ON THE ROLE OF SOLUTION CHEMISTRY
Materials Literature
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Plastic flow and strength of uranium and its alloys
The mechanical behavior of uranium and its alloys is reviewed with special emphasis on plastic flow behavior of polycrystalline materials. The strength of uranium is influenced by crystal structure as well as by point, planar, and volume defects; wit these factors in mind, texture hardening, strain hardening, solute h…
The magnetic structure of Mn3O4Hausmannite between 4.7K and Neel point, 41K
A neutron diffraction study has been made on the magnetic structure of single crystalline Mn 3 O 4 from liquid helium temperature to the Neel point, 41K, and the nuclear structure at room temperature has been refined.
The work function of rubidium
Films of rubidium were deposited on quartz substrates by evaporation at pressures of less than 10−10 Torr. The work function of the films was determined photoelectrically, and at 140 K was found to be (2.261 ± 0.015) eV. Warming the film to room temperature caused an irreversible reduction of about an order of magnitu…
Luminescent transitions and conductivity in zinc oxide
Thermally and IR-stimulated luminescence and conductivity of Cu and Li doped ZnO single crystals have been investigated in the temperature range from 5 to 100 K. It is shown that the stimulation of the green emission is related to the generation of free charge carriers, while the yellow emission is produced mainly by…
Elastic energy and line directions of grown-in dislocations in KDP crystals
The orientation factor, K, of elastic dislocation energy is calculated for dislocations in KDP (space group I42d) with Burgers vectors b = 〈100〉, [001], 〈110〉, 〈011〉, and 1/2〈111〉. As a result of elastic anisotropy, for dislocations with b = 〈110〉, K has an absolute maximum in pure screw orientation. The preferred lin…
Effect of heat treatment on the photoelectric properties of class I CdS single crystals
The photoelectronic properties of virgin CdS platelets, sublimed and cooled in an N2–H2S atmosphere, were altered by heat treatment in ultra-high vacuum. The untreated crystals showed a strongly structured spectral distribution of the photoconductivity (SDP) at liquid nitrogen temperature (LNT), having maxima (Class I…
The metastable phase Ni2Mo and the initial stages of ordering in NiMo alloys
The initial stages of ordering in Ni3Mo and Ni4Mo have been investigated by transmission electron microscopy and diffraction. The development of long-range order in Ni3Mo is associated with decomposition into the two metastable phases Ni2Mo and Ni4Mo, which are eventually replaced by the equilibrium Ni3Mo at a later s…
Segregation in alkali halide crystallization from aqueous solutions
Segregation from solutions and melts is compared theoretically. It is shown from thermodynamic arguments that equilibrium solution segregation is more effective. Segregation coefficients k0 are calculated for aqueous alkali halide systems, based upon theoretical heat of dissolution values (solid solution) and solubili…
Measurements of hyperpolarizabilities for some halogenated methanes
dc Electric-field induced optical second-harmonic generation has been measured for CH4, CH3F, CH2F2, CHF3, CF4, CClF3, and CBrF3. For CH4 and CF4 the third order hyperpolarizability χ(−2ω; 0,ω,ω) is obtained directly. For the other (dipolar) molecules, a bond additivity estimate for χ(−2ω; 0,ω,ω) is used to extract th…
Raman scattering inTi2O3-V2O3alloys
Raman scattering of single crystals of ${({\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{V}}_{x})}_{2}{\mathrm{O}}_{3}$ with $0\ensuremath{\le}x\ensuremath{\le}0.3$ has been measured between 80 and 700 \ifmmode^\circ\else\textdegree\fi{}K. All seven Raman-active phonons of the ${D}_{3d}^{6}$ space-group symmetry were found…
Relative effect of extra-atomic relaxation on Auger and binding-energy shifts in transition metals and salts
The relation between shifts in Auger energies and shifts in electron binding energies is explored. The prediction of Auger energies in metals from one-hole and two-hole optical energies as well as from electron binding energies in metals is described, with proper accounting for final-state coupling, relaxation, and re…
Mechanism of fast surface flashover in vacuum
Insulator samples of Plexiglas and alumina ceramic in vacuum have been subjected to high-voltage pulses with rise times of a few nanoseconds. Breakdown paths were inclined to the electric field in the presence of a magnetic field normal to the insulator surface, analogous to the Hall effect for bulk conduction. These…
Electronic structure and optical properties of layered dichalcogenides: TiS2and TiSe2
The electronic-energy-band structure of the layered dichalcogenides Ti${\mathrm{S}}_{2}$ and Ti${\mathrm{Se}}_{2}$ has been determined using the Korringa-Kohn-Rostoker (KKR) method. Crystal potentials were constructed from overlapping atomic charge densities in the muffin-tin approximation for both full Slater exchang…
Dielectric Properties of Di-n-Heptyl Azoxybenzene in the Nematic and in the Smectic-APhases
We report the dielectric constants of $p$, ${p}^{\ensuremath{'}}$-di-$n$-heptyl azoxybenzene in the nematic and in the smectic-$A$ phase. Around the nematic-smectic transition ${\ensuremath{\epsilon}}_{\ensuremath{\parallel}}$ decreases with decreasing temperature while ${\ensuremath{\epsilon}}_{\ensuremath{\perp}}$ i…
Divergence of Cholesteric Pitch near a Smectic-ATransition
We have measured the detailed temperature dependence of the cholesteric pitch in cholesteryl nonanoate near the smectic-$A$ transition. The data show a power-law behavior with an exponent $\ensuremath{\nu}=0.675\ifmmode\pm\else\textpm\fi{}0.025$, in agreement with theoretical prediction and with elastic-constant measu…
The Silica-Alumina System: Stable and Metastable Equilibria at 1.0 Atmosphere
Diffusion couples, consisting of sapphire and fused silica, which were annealed in the temperature range from 1678 degrees to 2003 degrees C and analyzed by electron beam microprobe, have provided data on the stable phase equilibrium of the silica-alumina system. Under stable equilibrium conditions, the intermediate c…
Optical characteristics of twisted nematic liquid-crystal films
A twisted nematic liquid crystal is shown by theory and experiment to rotate incident plane-polarised light by π/2 only at specified wavelengths. At other wavelengths, elliptically polarised light is produced. This action determines the contrast ratio of some twisted nematic devices.
Re-examination of the High-Temperature Resistivity Anomaly in ( Cr 0.01 V 0.99 ) 2 O 3
We report heat-capacity, x-ray, electrical-conductivity, and Seebeck-coefficient measurements in the range $200<T<900$ K, which indicate that there exist two high-temperature, band-type phases in ${({\mathrm{Cr}}_{0.01}\phantom{\rule{0ex}{0ex}}{\mathrm{V}}_{0.99})}_{2}$${\mathrm{O}}_{3}$. The electrical anomaly…
Temperature dependence of methyl group tunnelling rotation frequency
The temperature dependence is measured from 4 to 40 K of the frequency of tunnelling rotation of methyl groups in free radicals in gamma -irradiated methyl malonic acid crystals. Above 25 K the frequency, while remaining well defined, declines sharply with increasing temperature.