Materials Literature
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The mixing action of two crossed ultrasonic beams has been studied. The theoretical treatment of Taylor and Rollins is extended to include the all-pure-mode cases for the prosess $L ({\ensuremath{\omega}}_{1})\ensuremath{-}T\left\{{{\ensuremath{\omega}}_{2}}{{\ensuremath{\omega}}_{1}\ensuremath{-}{\ensuremath{\omega}}…
Finite ultrasonic velocity changes at the structural phase transition in SrTi${0}_{3}$ are observed for different modes. They are interrelated and correlated by theory. No critical effects are observed.
Heterojunctions of nZnSe–pGe switched from a high impedance to low in 100 nsec when a threshold voltage is exceeded. Resetting occurs in the opposite bias direction in 10 nsec after sufficient current is applied. Either state is maintained with all bias removed for a minimum of two weeks.
A sum rule is constructed which relates the third moment of the imaginary part of the dielectric function at zero wave vector to an integral of the product of the Laplacian of the crystal potential and the fluctuation of the electron density. This sum rule, though rigorous, will be of real use only when the real solid…
All the one-loop graphs of the dual-resonance model are explicity calculated. These graphs fall into three categories:planar, nonorientable, and orientable nonplanar. Using the properties of various elliptic functions, we are able to generalize the renormalization procedure, obtained previously for the planar diagrams…
The preparation and measurement of magnetic properties of cobalt-samarium permanent magnets prepared by liquid-phase sintering are discussed. Energy products in excess of 15×106 G Oe were observed. Long time exposure to air at 150°C did not degrade the samples.
The optical-phonon spectrum of ZnSi${\mathrm{P}}_{2}$ has been investigated by polarized Raman scattering at 6328 \AA{}. The results are compared with phonon modes in related tetrahedrally coordinated compounds and with a set of symmetry coordinates. The low-frequency dielectric constants are estimated from the Lyddan…
It has been suggested that two types of second sound, "drifting" and "driftless," are possible in dielectric crystals. The conditions for the existence of these two types of second sound are obtained, both from a heuristic analysis of the problem and from an exact solution of the complete linearized Boltzmann equation…
High-temperature powder x-ray diffraction photography and differential thermal analysis give 1643 K for the rhombohedral-to-cubic transition temperature of PrAl${\mathrm{O}}_{3}$; for NdAl${\mathrm{O}}_{3}$, this transition temperature is estimated to be 2020 K. The 800 K transition temperature of LaAl${\mathrm{O}}_{3…
Optical nonlinearities in crystals are for the first time analyzed from the rotational-invariance point of view. Several previous theoretical results are discussed on the basis of the decomposition of a tensor into irreducible parts. A proportionality between the spontaneous polarization and the vector parts of the no…
The observed degeneracy of mutually exclusive infrared- and Raman-active modes in MoS2 is traced by means of group theory to the weak van der Waals interaction between layers.Received 29 June 1970DOI:https://doi.org/10.1103/PhysRevLett.25.362©1970 American Physical Society
Measurements of the lifetime for positron annihilation in metals show a temperature dependence which has been ascribed to the trapping of positrons at vacancies. An explanation of this trapping process is presented in terms of an effective potential well, whose depth is the difference between the bottom of the positro…
Abstract The solubility behaviour of CuI was studied in KI‐acetone media in the concentration range of approximately 0.05 to 0.2 M. Within this range of iodide concentration, Cul 2 − was the only complex species found to occur in the liquid as well as in the solid phase. Conductometric studies also indicated the exist…
Potonie emend., is distally baculate and proximally smooth. Matonisporites Couper emened., has thicker corners, membraneous Y-rays and smooth exine. Callispora Dev emend., is characterized by having incipiently thickened angles and punctate exine. Boseisporites Dev emend., possesses two-layered exine, the outer layer…
The fatigue crack propagation behavior of Zircaloy-2 subjected to various environmental conditions was examined within the framework of linear elastic fracture mechanics. It was found that the fatigue crack growth rate increased with increasing levels of cold work, increasing temperature, and exposure to a water envir…
Abstract Release of potassium by extraction with solutions containing sodium tetraphenyl boron or by leaching with 0·1 N barium chloride seemed to be related to the nature of the mica layers in the interstratified minerals studied. The rate of potassium release was lower when the calculated Si/Al IV ratio of the mica…
Abstract Polyoxymethylene was successfully grafted with styrene, butadiene, and acrylonitrile by the mutual irradiation method in the monomer containing 18% of dimethyl formamide. The CO 2 and water vapor permeabilities and diffusivities were determined in the case of the butadiene‐ and acrylonitrile‐grafted products.…
The chemical and physical properties of cotton fabrics treated with formaldehyde in the presence of an acid catalyst (HCl) under aqueous (Form W) and essentially nonaqueous (Form D) conditions were investigated. Physical properties (tear strength, breaking strength, and crease recovery), functional group content (acid…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntermediates in the titanocene-promoted fixation-reduction of molecular nitrogenEugene E. Van Tamelen, Douglas A. Seeley, Stewart W. Schneller, H. Rudler, and W. CretneyCite this: J. Am. Chem. Soc. 1970, 92, 17, 5251–5253Publication Date (Print):August 1, 1970Publication Hi…
Abstract Synthesis of the first totally organic spiro polymer was accomplished by the reaction of 1,4‐cyclohexanedione and pentaerythritol in benzene plus a trace of p ‐toluenesulfonic acid to produce the polyspiroketal. The polymer did not melt, but began to decompose at 350°C. Although it was insoluble in most commo…