Materials Literature
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It is pointed out that in potential theory the validity of the Glauber approximation for high-energy scattering from a composite system implies a high degree of cancellation in the multiple-scattering series for the same process: The off-shell contribution to double scattering must be precisely cancelled by the sum of…
Carbonados are porous aggregates of mostly xenomorphic diamond crystallites ranging in diameter from a fraction of a micron to over 20 microns. Crystalline inclusions (up to 3 percent) occur in the pores of the crystallites and consist mainly of orthoclase and small amounts of other igneous, metamorphic, and secondary…
It is shown theoretically that the motion of liquid crystals through capillaries may resemble that of a plug, the velocity profile being flat rather than parabolic.Received 16 June 1969DOI:https://doi.org/10.1103/PhysRevLett.23.372©1969 American Physical Society
The electrochemistry of copper, silver, gold, gallium, indium, thallium, and their ions, and of chlorine and bromine in fused AlCl 3 –NaCl–KCl was investigated by electromotive force (e.m.f.) and voltam-metric techniques. Univalent oxidation states were observed for all the metals. In addition, copper was further oxid…
Polarized Raman spectra of an anhydrous single crystal of LiNO3 have been obtained under optimum experimental conditions. The internal vibrations of the nitrate ion are observed as follows: ν4(Eg) = 735.4, ν1(A1g) = 1071.0, and ν3(Eg) = 1384.6cm−1; these frequencies are essentially independent of the cation in the hos…
Neutron-diffraction measurements made on powder samples of the intermetallic compounds, DyPt3 and DyIn3, show that these compounds exhibit antiferromagnetic ordering below Néel temperatures of 13.2° ± 0.3°K and 24° ± 0.5°K, respectively. The magnetic reflections from DyPt3 can be indexed on a doubled chemical cell of…
The low-temperature thermal transport properties of an insulating crystal with an arbitrary concentration of randomly located phonon scattering centers are found for slab geometry. The phonon distribution function, the distribution of temperature, the Kapitza resistance at the boundaries, and the heat flux are evaluat…
Ammonium fluoride II and III have been recovered at 100°K and atmospheric pressure and examined by x-ray powder diffraction and by thermal analysis. The structure of phase III is closely related to that of cesium chloride. Phase II when heated from 100°K at atmospheric pressure transforms to a new phase, designated V,…
The results of an analysis of the energy transfer and two-step excitation in LaF3:Yb,Er are presented. The physical model assumes that the Yb3+ and Er3+ ions are tightly coupled and transfer occurs both ways. The simple model used is able to explain the experimentally observed time dependence and radiant efficiency pr…
The infrared and Raman spectra for the three alkali-metal nitrates LiNo3, NaNO3, and KNO3 have been measured in the region from 1600 to 30 wavenumbers, and a normal-coordinate analysis has been made for these compounds with a special emphasis on the rotational and translational lattice modes in the crystal. All three…
A mathematical solution to predict the properties of the strain waves generated when an explosive detonates inside a spherical cavity in an infinite medium is presented. In the case of commercial explosives in rock, the strain pulse is a highly damped oscillating wave train the characteristics of which depend on the p…
Magnetic-susceptibility measurements on cerium magnesium nitrate covering frequencies from dc to 200 Hz indicate that it undergoes an antiferromagnetic phase transition in the millikelvin range.Received 11 June 1969DOI:https://doi.org/10.1103/PhysRevLett.23.308©1969 American Physical Society
Abstract Octaäthylporphin (OÄP) wird mittels H 2 O 2 und konz. Schwefelsäure “oxidativ umlagert”: Neben dem Gemini‐monoketon 1 werden die Gemini‐diketone 3–7 , sowie die Gemini‐triketone 8 und 9 isoliert und mittels NMR identifiziert. Danach wird ein 2‐Stufen‐Verfahren zur Herstellung von 9 entwickelt: Behandlung von…
Magnetomechanical ratios for four Fe-Co alloys were measured by the Einstein-de Haas method. Previous measurements of Fe, Co, Ni, and Fe-Ni and Co-Ni alloys are reviewed, thus completing magnetomechanical determinations for the binary alloys of these three ferromagnetic elements. Magnetomechanical ratios for these bin…
The ultraviolet-absorption spectra of europium and ytterbium ions in Ca${\mathrm{F}}_{2}$ crystals have been measured at room and liquid-nitrogen temperatures. Their spectra are similar to each other in the general location of their absorption bands. Both spectra consist of: (i) $4f\ensuremath{\rightarrow}5d$ bands, b…
Shocked Bamle enstatite partly transforms to disordered enstatite. Debye-Scherrer patterns of some shocked material are almost identical to those of disordered enstatite from portions of various enstatite achondrites. No disorcdered single crystals have been found.
The recently characterized " white " allotropic form of carbon has been produced at high temperature and low pressure during graphite sublimation. Under free-vaporization conditions above approximately 2550 degrees K, the white carbon forms as small transparent crystals on the edges of the basal planes of graphite. Th…
Photoemission measurements on the magnetic semiconductors EuO, EuS, and EuSe show emission from $4{f}^{7}$ states which lie in the gap above the top of \ensuremath{\sim}2- to 3-eV-wide valence bands. These measurements, together with optical data, indicate semiconductor energy gaps of 4.3, 3.1, and 3.1 eV for EuO, EuS…
The results of measurements of the spin-lattice relaxation properties of mixed single crystals of chromium and aluminium acetylacetonate are reported. Measurements were made at microwave frequencies (9·3 GHz) in the range of liquid helium temperatures. In dilute crystals, where the investigation was primarily concerne…
EPR spectra differing in hyperfine splitting have been reported for Mn (II) ions in Ν,Ν-Dimethylformamide (DMF) when using Mn (ClO 4 ) 2 and MnCl 2 . The difference in the reported spectra is shown to be due to the species MnCl 4 2⊖ by a mole ratio plot. The presence of MnCl ⊕ is also indicated by a mole ratio plot. T…