Materials Literature
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It is pointed out that the absorption lines of the lanthanides that are peculiarly sensitive to changes in the ligands are consistent with the selection rules for quadrupole radiation within the 4f shell. A number of sources for this sensitivity are examined, and it is concluded that it owes its origin to the inhomoge…
Abstract The X‐ray diffraction patterns of two crystalline forms of isotactic polypropylene, the β‐ and γ‐forms distinct from the α‐form described by NATTA 1 , have been recorded. The β‐form, previously observed only as single spherulites 6 has now been obtained in a well crystalline polymer, practically free of α‐for…
Abstract A technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter‐comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activati…
Abstract Changes in ultra-violet absorption spectra have been measured for nitrates and nitrites of the alkali metals and for ammonium, silver and thallous nitrates, in relation to thermal transformations in these solids. A gradual shift of absorption bands is found to accompany thermal expansion of all the crystals.…
Abstract Ultra-violet absorption spectra of ions in crystals are sensitive to their environment of neighbouring ions. This fact is utilized to study melting processes in nitrates and nitrites, with particular reference to changes in the average shell of nearest neighbours around any ion, on passing from crystal to mel…
We have measured with precision the temperature and pressure dependence of the Co59 nuclear resonance chemical shift (σ) in the octahedral cobalt complexes Co(NH3)63+, Co(CN)63—, and Co(NO2)63— in aqueous solution. The pressure and temperature range was 1 to 10 000 kg/cm2 and 3° to 80°C, respectively. From the pressur…
Measurements of the electronic properties of a wide variety of organic salts formed from the anionradical of tetracyanoquinodimethan (TCNQ) and various cations have been made. The results indicate that in the highest conductivity salts, which have conductivities of the order of 100 Ω—1 cm—1, the electrons are degenera…
The optical reflection spectra from 12 500 to 50 000 cm—1 were studied for a series of coprecipitated chromia—alumina samples calcined between 500° and 1400°C. The Melamed theory was employed to obtain extinction coefficients from these spectra. The Racah parameter B and the wavenumbers of the two visible transitions…
The well-known equation of Davies and Jones for the pressure dependence of the glass transition temperature, dTg/dP=Δβ/Δα=TgVΔα/ΔCp, depends on two independently testable hypotheses: that a one-parameter description of the excess thermodynamic functions is adequate, and that the glass transition occurs when some one t…
Magnetic susceptibility measurements have been carried out on a wide variety of organic salts based on the anion radical of tetracyanoquinodimethan (TCNQ). A correlation between the magnetic and electrical properties has been observed. Salts which exhibit the higher conductivities also exhibit a temperature-independen…
The dispersion relation for the normal modes of vibration propagating along the [$\ensuremath{\zeta}00$], [$\ensuremath{\zeta}\ensuremath{\zeta}\ensuremath{\zeta}$], and [$0\ensuremath{\zeta}\ensuremath{\zeta}$] directions in a single crystal of pure gallium arsenide at 296\ifmmode^\circ\else\textdegree\fi{}K has been…
The thermoelectric power ($\ensuremath{\alpha}$) of $p$-type SnTe has been measured between room temperature and 450\ifmmode^\circ\else\textdegree\fi{}C for apparent hole concentrations (${p}^{*}=\frac{1}{e{R}_{300}}$) between 1\ifmmode\times\else\texttimes\fi{}${10}^{20}$ and 1.8\ifmmode\times\else\texttimes\fi{}${10…
We determined the viscosity of rhyolite glass at temperatures between 350° and 850°C, water pressures between zero and 68.9 bars, and water content between 0.1 and 3 weight per cent. Our technique was to construct a compaction rate curve for the rhyolite glass under known conditions of temperature, water pressure, and…
The rare-earth ions may exist in the divalent state in suitable host crystals such as CaF2. All of the trivalent ions from Ce to Yb (and probably also La) are reduced in situ to the divalent state in CaF2 by gamma irradiation. The spectra of most of these ions show that the ground and first few excited states derive f…
An analysis of thermal conductivity is presented which differs from that of Klemens and of Callaway in that it considers explicitly the conduction by both transverse and longitudinal phonons. This approach is then used to provide a very good fit to the data on silicon from 1.7 to 1300\ifmmode^\circ\else\textdegree\fi{…
Experiments on clotting, both in vitro and in vivo, showed that a colloidal graphite surface, when rinsed with a cationic, surface-active agent, was capable of bonding heparin. The resistance of this graphite-heparin surface to the formation of clots was far greater than plastic or silicone surfaces in comparable stud…
Copper, shown to be present in significant amounts in monoethanolamine, MEA, scrubber solutions, is an active catalyst for the serious degradation of the amine. Makeup water, drawn from the ship's potable water supply, appears to be a major source of this metal. The recommended substitution of battery-grade for potabl…
A nonlinear differential equation describing the steady-state operation of a current instrument transformer is formulated based upon a Rayleigh hysteresis loop approximation of the magnetic core effects. Using a harmonic-balance technique, a suitable approximate solution of this equation provides expressions for the R…
The high‐temperature energy relations in some alkaline‐earth and lead borate glasses and compounds of the same compositions are reported. The data obtained with a continuous high‐temperature calorimeter and by solution calorimetry in 2 N nitric acid were combined to give heat content versus temperature curves from 25°…
Studies of the physical and chemical forms of I131 fallout following the USSR nuclear tests of late 1961 and the United States and USSR studies of 1962 have shown that the fraction existing in the gaseous state varied from about 10 to 90 per cent. Very little of the gaseous I131 appeared to be in the elemental or HI f…