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 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…
The 1s, 2s, 2p, and the four equivalent 3d hydrogen-atom wavefunctions were expanded as linear combinations of functions of the form, exp ( —ar2), without the use of spherical harmonic functions to give angular dependence. The Gaussian functions were located at different points in space in order to give the proper orb…
A regular domain pattern has been observed to form in nematic liquid crystals when an electric field is applied. The domains are visible in unpolarized light by either transmission or reflection. Both ac and dc fields produce similar domain patterns and these appear at a rather sharp threshold field of about 1000 V/cm…
Extensive deposits of kaolinite in Florida are formed by transformation of montmorillonite during low-temperature supergene weathering. The transformation occurs by intracrystalline leaching of interlayer cations and tetrahedral silica layers. Interposition of stripped layers within montmorillonite creates a regular 1…
The presence of limited amounts of water appears to improve the quality of anhydrous oxalic acid single crystals grown from acetic acid solutions. Water concentrations in the saturated solutions which allow crystallization of the anhydrous acid have been determined from the phase study of this ternary system. Near 50…
Magnetic and structural properties of the tetragonal phase of ternary Cu (0–12.5 at%)–Mn(55–42.5 at%)–Al(45 at%) alloy have been studied in relation to binary 45Al-Mn alloy. The substitution of Cu to Mn-Al alloy reduces the tetragonality c/a of the tetragonal phase from 1.30 of the 45Al-Mn to 1.20 of the 10 at% Cu all…