Materials Literature
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The structure of alpha -phase potassium nitrate (KNO 3 ) has been determined at room temperature (25 degrees C) and closer to the alpha to beta transition temperature at 100 degrees C, from three-dimensional neutron diffraction data. The present results indicate that the potassium atoms experience small but significan…
The first stages of oxidation of niobium (NbOx) have been studied by electon microscopy. Two phases, called NbOxI and II were detected. A study of NbOz will be published elsewhere. Niobium has been oxidized by a wet argon flow on thin foils or powders, heated at temperatures from 350 up to 400°C. NbOxI, which has the…
The phase diagram and crystal structure of vanadium–deuterium alloys have been studied by means of neutron and X-ray diffraction as well as heat capacity measurements. In addition to a disordered solid solution (α-phase), the following three ordered phases have been found at relatively low temperatures, i.e. a β-phase…
The results of measurements on the conductivity of single crystals of SnS2 in a direction parallel to the c-axis are given. Prior to forming, space charge injection is shown to be the predominant mechanism and subsequently for the formed crystal the relation between current and voltage is I ∝ Un where n may be as high…
Differential thermal analysis and thermogravimetric analysis of sodium azide diluted with sodium chloride both show one major peak followed by a second minor one. This is interpreted as indicating the occurrence of two distinct decomposition processes. The activation energy of the first, major process was 36 kcal/mol,…
A complete diagonalization of the matrices for the electrostatic, spin-orbit, and crystal field interactions for Sm3+ in LaCl3 has been carried out using a truncated set of basis vectors containing 42 of the 73 LS states. This diagonalization allowed many new assignments to be made. Corrections of some of the centers…
The lattice dynamics, second- and third-order elastic constants, and the anisotropic thermal expansion of hexagonal titanium are worked out using Keating's approach. The ten third-order elastic constants are calculated using five third-order parameters. The experimental measurements on the pressure derivatives of the…
Several substituted pentaerythritol compounds [R—C(CH2OH)3, where R = COOH, CH3, NO2 and NH2] have been found to undergo phase transitions to plastic crystals. With the exception of R = NH2 (which has only one detectable diffraction line in the plastic state), the crystals are f.c.c., a ≃ 8.9 Å.
The drift mobility of excess holes has been investigated in undoped NiO crystals using a transient technique with electron-beam excitation. Specimens with low-impurity content were grown epitaxially from the gas phase. At room temperature ${\ensuremath{\mu}}_{h}$ lies between 20 and 50 ${\mathrm{cm}}^{2}$ ${\mathrm{V}…
Lithium metavanadate is monoclinic with a = 10.158(2), b = 8.4175(9), c = 5.8853(9) Å, β = 110.48(2)° and probable space group C2/c. The structure, refined by least-squares to a ωR = 0.033 using 851 reflections, is isotypic with LiAlSi 2 O 6 (spodumene) and LiFeSi 2 O 6 . Bands of Li—O edge-shared octahedra run parall…
The paramagnetic behavior of localized states in amorphous chalcogenide alloys and the tetrahedrally coordinated amorphous germanium has been studied by ESR experiments. No signal has been detected in any of the chalcogenide glasses, prepared by quenching from the melt, with a sensitivity of about ${10}^{11}$ spins/G…
Experimental values of the $g$ and hyperfine components of ${{X}_{2}}^{\ensuremath{-}}\ensuremath{-}{V}_{K}$ centers and ${{Y}_{2}}^{\ensuremath{-}}\ensuremath{-}{V}_{K}$-type centers ($X, Y=\mathrm{F},\phantom{\rule{0ex}{0ex}}\mathrm{C}\mathrm{l},\phantom{\rule{0ex}{0ex}}\mathrm{B}\mathrm{r},\phantom{\rule{0ex}{0ex}}…
Infrared reflectivity and absorption measurements have been made on single-crystal epitaxial GaN on (0001) $\ensuremath{\alpha}\ensuremath{-}$${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ crystals. Analysis of the normal-incidence reflectance data on low-carrier-concentration layers using the Kramers-Kronig technique and diel…
The diffraction patterns of both silica and germania glasses are consistent with a structure in which nearly all of the atoms belong to tridymite-like regions of up to about 20 angstroms or more that are bonded efficiently together in a manner analogous to that found in twinned crystals.
SUMMARY In situ tensile straining was carried out in the 1 million volt electron microscope in an attempt to clarify the mechanism(s) of superplasticity in the Zn/Al eutectoid alloy. The dynamic microstructural observations in the 1 MV microscope at 100°C at an m value of ∼0.3 were consistent with 100 kV observations…
Abstract In order to study thermal degradation of copolymers and homopolymer mixtures of methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and styrene mild pyrolysis on a hot filament, followed by gas chromatography, was used. For each of the eight monomer pairs, at least eleven…
Thirty‐two years after the addition of high rates of potassium to two Illinois experiment fields, the largest gain in soil K was in the acid‐insoluble form. Cation exchange capacity of the soil clays had decreased with the increasing addition of K, presumably due to fixation of potassium in the interlattice positions…
The characteristics of secondary electron emission from glass surface by Ar+ ions were investigated experimentally. The yields of glass and quartz microsheets were larger than that of stainless steel. It was first observed that Field Enhanced Emission and Self Sustained Emission were caused by the surface charge. Beca…
The effect of the grain size on the irradiation-induced expansion of diamond has been experimentally shown. Under the similar irradiation conditions (integral neutron flux of 1.4. 1019 n/cm2 E > 75 eV, temperature 130°C) 200 μm and 0.1 μm diamond powers expand up to 0.67 and 1.72% respectively.
The relation between lamellar spacing λ and growth rate v has been studied from the energetic considerations for the lamellar eutectic growth. Three free energy sinks were considered; namely, the kinetic process for solidification, diffusion and solid phase boundary formation. The free energy for the kinetic process w…