Materials Literature
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A piezoelectric ceramic material having low dielectric constant, high thickness coupling factor, high mechanical quality factor, high stability, and high operating temperature, has been prepared from PbTiO3 incorporated with 2.5 mol% of LaO12 and 1.0 mol% of MnO2. Typical electromechanical constants of this material a…
Abstract The validity of boron as a salinity index has been established by numerous studies over the past 2 decades. It is known that all the major clay minerals may contain boron which can be correlated with paleosalinity. However, under given conditions, illites will contain the most boron and kaolinites the least.…
Thermal quenchings of +3 rare-earth line emissions were measured for excitation into the 4fn emitting states. These quenchings differ from corresponding quenchings reported by Wickersheim and Buchanan for band-gap excitation. For Tb+3, Tm+3, and possible Pr+3, the quenchings from the 4fn emitting states are attributed…
Abstract One-g samples of a montmorillonite, a metabentonite, an illite, two kaolinites, and three halloysites were treated with 50 ml of hydrochloric acid (6·45 N, 1: 1), acetic acid (4·5 N, 1: 3), sodium hydroxide (2·8N), sodium chloride solution (pH 6·10; Na = 35‰; Cl = 21·5‰), and natural sea water (pH 7·85; Na =…
Some fundamental aspects of electromigration phenomena as they have been studied in "bulk" metallic conductors are reviewed. In an electric field atoms are subjected to a force due to the field, and to a force which results from the motion of electrical carriers, electrons, or holes. In bulk samples, and at high tempe…
The effect of variations of the area of two metals in a galvanic couple is discussed for three common cases. In Case 1, it is assumed that the only significant process on the more active metal (A) at the galvanic potential (ϕg) is metal oxidation (dissolution), while the only significant process on the more noble meta…
The effects of temperature and hydrostatic pressure on the ferroelectric (FE) properties of PbTiO3 and on certain properties of BaTiO3 which have not been treated or emphasized earlier were investigated. For PbTiO3, the FE-paraelectric (PE) transition is of first-order, and the transition temperature, Tc, decreases wi…
The x-ray scattering by two different rutile crystals, within a hemisphere of reciprocal space having radius (sin θ) /λ=1.02 Å−1, was measured at 298°K with PEXRAD. The integrated intensities of 780 reflections from each crystal were determined, resulting in 136 symmetry independent Fmeas from Crystal 1 and 122 Fmeas…
Machine learning (ML) is transforming all areas of science. The complex and time-consuming calculations in molecular simulations are particularly suitable for an ML revolution and have already been profoundly affected by the application of existing ML ...Read More
The effect of salinity on the temperature-depth relations of a brine of constant composition, enclosed in a vein system, but freely connected to the surface, and everywhere at the boiling point for the hydrostatic head, was calculated by using a mathematical model. The Na-Ca-K-Cl brines which are found in thermal spri…
Study of the time dependence of physical properties in the transformation range of glass is complicated by the “memory effect” and the inherent nonlinearity which are characteristic of structural relaxation. A multiparameter model of structural relaxation is presented that differs from earlier models in that it takes…
The review considers methods for the determination of tautomeric composition from NMR spectra and gives a systematic account of the results of studies on keto–enol tautomerism. The bibliography includes 160 references.
Abstract A detailed proton nuclear magnetic resonance study has been made of the influence of temperature and water content upon the nature of water adsorbed on collagen fibres. A refinement of a previously reported analysis of time-averaged tensor properties of the water molecule with respect to the fibre axis suppor…
Abstract Crystalline 9-cyanoanthracene undergoes photodimerization to give the trans dimer which is unexpected on the basis of the topochemical preformation theory. The possibility that the reaction occurs at defects is investigated; and the nature of the structural imperfections are described, as are also the types o…
Electric-field-induced scattering by normally Raman-inactive LO phonons is observed in the IV-VI-compound (NaCl structure) semiconductors PbTe and SnTe with Pb films on $p$-type samples to induce energy-band bending. The observed Raman peaks correspond to unscreened $q\ensuremath{\approx}0$ LO phonons. A discussion of…
For a duration of several times ${10}^{\ensuremath{-}12}$ sec, TO modes are excited to an occupation number exceeding the equilibrium value (at 300\ifmmode^\circ\else\textdegree\fi{}K) by more than thirteen orders of magnitude. The relaxation times of these phonos are measured directly and found to agree with the know…
A precision study has been made of the temperature dependence of the Hall effect and resistivity in five carefully selected natural semiconducting diamonds. The donor and acceptor concentrations in each sample have been calculated from the Hall effect data, and the acceptor concentrations are shown to correlate excell…
The thermal diffusivity of BN has been measured from 100 K-800 K using a 'flash' method; published specific heat data has been used to evaluate the thermal conductivity. Over a limited temperature range the results have been confirmed by steady state measurements. The thermal conductivity parallel to the deposition pl…
A short study of the anomalous wavelength dependence of photoresponse in insulating single crystals of GaSe is given. This anomaly can be roughly related to the number of structure defects in the crystal. From the nature of the effects it is concluded that the origin of the anomaly differs somewhat from the situation…
The phosphorescence spectra of benzaldehyde-h6, −1d1, −4d1, −3, 5d2 and −d6 have been studied optically in close packed matrices (acetophenone and methyl benzoate) and relaxed matrices (methylcyclohexane and perfluoro-n-hexane) at 4.2°K. All the spectra were sharp and could be analyzed vibrationally. In the close pack…