Materials Literature
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Exact and approximate methods for determining the momentum distribution of electronic systems from Compton scattering measurements are presented. The method used previously to analyze Compton scattering measurements, the impulse approximation (IA), is derived from first principles, and its accuracy is compared with th…
Misfit dislocations are often transported to the interface between crystals by glide. In materials with the diamond or sphalerite structures, glide is inhibited by the Peierls stress. The aim of this paper is to present a theory for misfit accommodation which includes the effect of the Peierls stress. It is used to ex…
Raman spectra are reported from single crystals of graphite and other graphite materials. Single crystals of graphite show one single line at 1575 cm−1. For the other materials like stress-annealed pyrolitic graphite, commercial graphites, activated charcoal, lampblack, and vitreous carbon another line is detected at…
Abstract Poly(2,6‐diphenyl p ‐phenylene oxide) exists in at least two crystalline modifications. One modification can be obtained by crystallization from solution or by thermal crystallization of undiluted polymer. The other modification, however, can only be obtained by crystallization from solution. The solvent, e.…
Magnetically "dead" layers, previously observed in iron films at room temperature, are observed in nickel. From the temperature dependence of this effect it is deduced that two dead layers persist at $T=0$, independent of the film thickness. Existing theories of magnetic thin films are unable to account for these obse…
We present a calculation of the dielectric correlation function in glasses showing how the assumption of short correlation length for normal modes breaks the momentum selection rules and leads to expressions for the first-order Raman-scattering intensity in terms of the density-of-states functions and known frequency-…
Abstract The stress-strain curves of Cu and Cu + Zn alloys containing alumina particles have been measured as a function of temperature, strain rate, composition, volume fraction and radius of the particles. Around room temperature the stress-strain curves of the Cu alloys are strongly temperature dependent and there…
Abstract Electron microscope studies of deformed single crystals of Cu and Cu + Zn alloys of various compositions containing small alumina particles show that the dislocation structures generated and associated with the particles consist generally of prismatic loops, Orowan loops as well as prismatic loops in some bra…
Unlike other ferroelectric perovskites, PbTi${\mathrm{O}}_{3}$ displays temperature-dependent Raman spectra consisting of underdamped modes, including the "soft" transverse-optical (TO) modes. Moreover, the softest TO mode shows linewidth divergence at the ferroelectric-to-paraelectric transition. Also in contrast to…
On the basis of the classical assumption of interatomic central forces, a method is proposed for the computation of the structure and energy of a grain boundary: It is applied to the particular case of symmetrical tilt boundaries around [100] in Al and Cu. The resulting curve shows that the interfacial energy is almos…
The influence of deviations from stoichiometry and titanium additions on the flow stress of polycrystalline Ni3Al has been determined in the temperature range — 196 to 1000 °C. The flow stress is found to be sensitive to small composition changes within the phase field. In particular, aluminium-rich deviations from st…
Experimental measurements of the low field d.c. conduction in both polycrystalline and single crystal yttria-stabilized zirconia are presented. Comparison shows that conduction in the single crystal material is little different from the polycrystalline counterpart. Results were obtained on a range of polycrystalline s…
Solid solutions in the system YPO4–YVO4, with and without 2 mol% of Tb3, were studied to determine the reason for the total inactivity of Tb in YVO4. The comparison of the diffuse reflectivity of Tb-containing solutions with that of Tb-free ones shows a uv absorption at energies below the absorption edge of YVO4 in ma…
Magnetic susceptibility and low-temperature specific-heat measurements have been made on several specimens of polycrystalline high-purity titanium, and in the case of the former measurement, on four single crystals. The calorimetric results are in good agreement with previously published data. A critically assessed av…
The quantum yield of a semiconductor thin-film photocathode, operating in the transmission mode, has been derived from the continuity equation and light multiple reflections within the film and the substrate. The fit between experiment and theory is good for hv<1.7 eV. The differences between experiment and the…
The optical constants of amorphous Ge films formed under well-defined conditions have been determined in the 0.1-25.0-eV spectral range. In the 0.1-1.8-eV range they were determined by analysis of precise reflectance and transmittance data ($\mathrm{RT}$), and in the 0.1-25.0-eV range by a Kramers-Kronig analysis of n…
Crystals of lactate dehydrogenase (LDH) were frozen by equilibration in a sucrose-ammonium sulfate solution, and then dipping into liquid nitrogen. The rate of radiation damage for frozen crystals was tenfold less than for crystals at room temperature. The physical properties of frozen crystals are discussed. Analysis…
Aluminum spheres were fired vertically into dry quartz sand in the light-gas gun facility at the NASA Ames Research Center. A velocity of 6.37 km/sec and a chamber pressure of 150 μ were used for all shots. Using an estimated impact pressure of 500 kb, heating of the target was computed to be 26% of the initial projec…
Abstract The morphology of porous anodic oxide films formed on aluminium in phosphoric acid electrolytes at constant current density or voltage, and under changing electrical or electrolytic conditions, has been studied quantitatively by electron microscopy. Replicas from film sections and from both film interfaces ha…
Using de Vries's model, we predicted theoretically that phase matching of optical third-harmonic generation can be achieved in cholesteric liquid crystals. The prediction was verified by measurements of third-harmonic generation from a mixture of cholesteryl chloride and cholesteryl myristate.