Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
The normal tungstates (R2O3·3WO3) of all rare-earth elements have been prepared as well as the 1:1 oxytungstates (R2O3·WO3) of all except Sc and Ce. Physical properties were studied with particular emphasis on luminescence.
An applied field of 105 V/cm produces electron emission from apparently smooth surfaces at room temperature. It is found experimentally that this prebreakdown emission is independent of emitter temperature up to 1000°K. Using a shadow electron microscope, projections about 2 μ high capable of producing field enhanceme…
It is shown that the bond length of an SO bond and the bond angle of an SO 2 group may be very satisfactorily correlated with the SO stretching frequency. The bond-length – stretching-frequency relationship is used to predict some bond lengths that have not been measured and the OSO angles in some sulphuryl compounds…
The "shell model" of an alkali halide is extended to take into account short-range forces between both first- and second-nearest neighbor atoms in the crystal, the polarizability of both ions, and the possibility that the ionic charge may be less than one electronic charge. The arbitrary parameters of the model have b…
The disordered structure above the Curie temperature (about 160°C) of NaNO 2 was studied by the X-ray diffuse scattering. The observed diffuse scattering, the satellites or the diffuse maxima and the plate-like diffuse scattering normal to the b * axis around them, can be interpreted on the basis of a certain disorder…
The relative phosphorescence to fluorescence quantum yields and phosphorescence lifetimes of naphthalene have been measured in a number of glassy media, some of which contain perturbing atoms of large atomic number. The intersystem crossing process S′→T is very sensitive to external heavy-atom perturbation. It is show…
Abstract The growing interest in the use of CO2 in crude oil recovery increases the need for data on the effect of CO2 on hydrocarbon physical properties. Data are presented on the solubility of CO2 in various dead oils, the swelling changes in CO2 -oil solutions and the effect of CO2 on dead oil viscosity. This later…
Abstract Differential thermal analysis was applied for the investigation of melting and crystallization behavior of high polymers. The heats of fusion of crystalline regions were obtained as follows: 45.6 cal./g. for nylon 6, 46.8 cal./g. for nylon 66, 47.9 cal./g. for nylon 610, 54.1 cal./g. for nylon 11, 58.7 cal./g…
Abstract Kinetic studies have been made of the thermal decomposition of precipitated calcium carbonate, powdered calcite, and regular fragments of calcite crystals. The powdered materials were examined in the form of pellets, which were prepared by compacting the powder to about 70% of its theoretical density. The wor…
Earlier work in this laboratory on tracer diffusion of solutes in βTi, which resulted in abnormally low values of activation energy and frequency factor, has been extended to higher temperatures. Diffusion coefficients for the solutes Nb, Mo, Cr, Mn, Fe, Co and Ni have been measured over the whole available temperatur…
Structures of silicon and germanium (111) surfaces produced at room temperature by the Gobeli—Allen cleavage technique have been studied by low-energy electron diffraction. Both have a rectangular unit mesh which measures √3×1 with respect to the parallel threefold symmetrical substrate mesh. Thus three domain orienta…
X-ray and optical data have been obtained on vaterite single crystals grown by ionic diffusion in aqueous solution. These data indicated that vaterite has hexagonal symmetry with a prominent pseudo-cell where a' =4.13, c'= 8.49 ~, Z' =2. Five weak superstructure reflections have also been observed. These show the true…
To account for spherulitic crystallization from the melt, one must explain the origins (i) of fibrous crystal habits in the absence of appreciable temperature gradients and (ii) of profuse noncrystallographic branching. Attention is drawn to properties held in common by spherulite-forming melts of various types and, i…
Cross-linking is a process of considerabie commercial as well as biological importance. It gives useful properties to a wide variety of polymers; some, such as rubber would be almost useless if it did not occur. The facilitate of cross-linking for commercnai purposes, however, usually entails the use of heat or certai…
A series of small cation molybdates, MgMoO(4), MnMoO(4), FeMoO(4), CoMoO(4), NiMoO(4), and ZnMoO(4) with the wolframite structure characteristic of the corresponding tungstates have been synthesized at high pressure and temperature. The high-pressure compounds revert to the ambient pressure modifications if heated in…
Abstract An earlier paper (Bowden & Chadderton 1962) has described the damage produced by uranium fission fragments in the lattices of stable crystals. There is evidence that the lattice disarray is caused by both displacement and ionization processes. This paper deals with damage in thermally unstable crystals. T…
The temperature dependence of the cation-distribution parameter η, the lattice constant a, and the oxygen-position parameter u, for Mg1.06Fe1.94O3.97 has been established for quench temperatures between 410° and 1100°C. The fraction of magnesium ions on tetrahedral sites, η, increases from 0.12 to 0.28 in this tempera…
The vaporization of lithium and sodium metaborate has been studied mass spectrometrically. The vapors of these compounds consist principally of the monomers LiBO2 and NaBO2, with some dimer and a very small amount of trimer also present. Heats of vaporization of the two metaborates and of boron oxide were determined w…
The dynamic behavior of oxygen vacancies associated with the solid solution of CaO in Th${\mathrm{O}}_{2}$ is treated using an 8-position nearest neighbor model. This treatment predicts an internal friction peak characterized by a single relaxation time and a dielectric loss peak with a single relaxation time equal to…
The vapor pressures of lithium oxide, boric oxide, and lithium metaborate have been measured by the torsion—effusion method. For lithium oxide, the magnitude of the observed pressure indicates vaporization largely to lithium oxide molecules. The boric oxide measurements yield an entropy for B2O3(g) that is consistent…