Materials Literature
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A new paramagnetic center was produced by 550-kV electrons in hexagonal boron nitride. It is shown that this center is a three-boron center and consists of an electron trapped in a nitrogen-ion vacancy ($F$ center). The hyperfine interaction was found to be anisotropic with ${A}_{\ensuremath{\perp}}=40.0\ifmmode\pm\el…
A detailed study of changes in the internal fields at Mn, Fe, and Si nuclei in the solid solutions of ${\mathrm{Fe}}_{3\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Si}$, $0\ensuremath{\le}x\ensuremath{\le}1.6$, as a function of composition has been made by spin-echo NMR at 1.28 K and in zero external magnetic field. Reson…
At about 810\ifmmode^\circ\else\textdegree\fi{}C niobium dioxide undergoes an apparently second-order transition between a high-temperature (HT) rutile structure and a low-temperature (LT) phase whose structure is slightly distorted from rutile. The primary order parameters of the transition are the amplitudes of sinu…
Electrical properties of amorphous evaporated electrochromic (molybdenum trioxide) films were studied in various ambients. It is shown that at a given applied voltage there is a "humidity threshold" below which coloration does not occur. The transient behavior of the current and remnant voltage in low humidity (precol…
Abstract The XPS studies of chromia–alumina catalysts were carried out to elucidate the surface of these catalysts. Photoreduction was found to occur during the XPS measurements. Therefore, all spectra were measured rapidly to prevent any photoreduction. It was found that the information about the spin-orbit splitting…
Longitudinal and transversal magnetostrictions of rapidly quenched amorphous alloys in (Fe_<1-x>Co_x)_<80>P_<13>C_7 and (Fe_<1-x>Co_x)_<75>-Si_<15>B_<10> systems were measured in the saturation magnetization region at room temperature. Forced magnetostrictions of these alloys were also measured in the magnetic field u…
Both Raman scattering and infrared reflectivity measurements have been performed to determine the optic-mode spectrum of orthorhombic ${\mathrm{KNbO}}_{3}$ at room temperature. Pincipal-axis phonons and oblique phonons were observed with a combination of 90\ifmmode^\circ\else\textdegree\fi{} scattering, back scatterin…
Transient charge and discharge currents in oriented PET films (Melinex) were measured over a wide range of temperature and electrical stresses. Some limited studies of the nature of these current transients were also made by varying parameters such as electrode material and the sample thickness. Isochronal characteris…
Some electrochemical aspects of the stress corrosion cracking (SCC) behavior of ASTM A517 Grade F steel in liquid ammonia environments at 25 C have been studied. Electrode potentials were measured during SCC tests by means of thallium/saturated thallous chloride/ammonia reference half cell. The effects of controlled a…
The large and small subunits of Escherichia coli glutamate synthase were isolated. The small subunit catalyzes the NH(3)-dependent synthesis of glutamate. The large subunit exhibits glutaminase activity.
The spontaneous magnetization and principal susceptibilities of the rare-earth orthochromites ${\mathrm{TbCrO}}_{3}$ and ${\mathrm{PrCrO}}_{3}$ are studied in the temperature range $4.2\ifmmode^\circ\else\textdegree\fi{}\mathrm{K}\ensuremath{\le}T\ensuremath{\le}{T}_{N}$. For the case of ${\mathrm{PrCrO}}_{3}$ the fie…
Cotton fibers blended to give three levels of fiber maturity were mercerized in anhydrous liquid ammonia and in sodium hydroxide solution, slack and under tension. Both reagents produced similar changes in the cottons, but to differing degrees. Both ammonia and caustic treatments produced changes in morphology (swolle…
A computer-oriented strategy has been developed for simultaneous evaluation and correlation of thermodynamic data on groups of chemically related species. A general empirical equation for the temperature dependence of the heat capacity of a species and derived functional relations for entropy, enthalpy, free energy, e…
The optical absorption spectra in 2-butanol have been studied. The position of the absorption peak which is attributed to surface plasmons of small alloy particles depends on the composition of the alloy. The spectra obtained are qualitatively in agreement with those calculated by Mie's equation.
Sonolysis of water at 447 kHz causes a decrease in the pH. The products formed depend to some extent on the nature of the dissolved gases; products observed are hydrogen peroxide, nitrous and nitric acid. The yield of hydrogen peroxide follows the order O 2 > air > Ar > N 2 . In the case of total acid (nitrou…
Abstract Mössbauer and i.r. spectra of a series of nontronites show that Fe 3+ and Al 3+ are distributed between tetrahedral and octahedral sites. The Mössbauer results have reaffirmed the occupation by Fe 3+ of octahedral sites at which these ions are coordinated to pairs of OH groups in both cis and trans configurat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal .sigma.-hydrocarbyls, MRn. Stoichiometry, structures, stabilities, and thermal decomposition pathwaysPeter J. Davidson, Michael F. Lappert, and Ronald PearceCite this: Chem. Rev. 1976, 76, 2, 219–242Publication Date (Print):April 1, 1976Publication History Published on…
A scale factor γ, to convert from the relative to the absolute/relative intensity scale, is readily calculated during computer simulation of powder patterns. Previously used scale factors are related to γ. The Reference Intensity Ratio, I/Ic (c = corundum), is obtained from μ, ρ, and γ for the sample and for corundum.…
The existence of optical second harmonic generation has been shown to be a highly reliable and sensitive physical test for the detection of crystalline non-centrosymmetry. A second harmonic analyzer has been constructed which can resolve space group ambiguities arising from Friedel's Law with a confidence level greate…
Abstract The solubility, permeability, and diffusion time lag for carbon dioxide in polycarbonate are reported at 35°C for pressures ranging from 1 atm to 23 atm. The solubility data are very well described by the dual sorption mechanism model, Henry's law plus Langmuir adsorption, proposed for glassy polymers. Both t…