Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Crystallographic studies of Ba 2 NaNb 5 O 15 have shown that the possible space groups are D 6 2 , C 11 2v and D 19 2h . The coincidences between the infrared and Raman spectra support the conclusion, based on the ferroelectric properties of the crystal, that the space group is C 11 2v . The anomalous tantalum compoun…
The dielectric properties of annealed single crystals of SrTi${\mathrm{O}}_{3}$ have been measured over the temperature range from 5 to 300 \ifmmode^\circ\else\textdegree\fi{}K. At temperatures below 50 \ifmmode^\circ\else\textdegree\fi{}K, electric double hysteresis loops are observed and associated changes in weak-f…
Laser-excited Raman spectra have been observed in single crystals of Y2O3, Y2O3(Eu3+), Er2O3, and YB2O3 at 10, 80, and 300 K. In Y2O3(Eu3+) the symmetries of the excited levels have been determined. The optically active phonons can be separated into two groups; in one group (above 300 cm−1) the internal vibrations of…
The formalism is developed for determining the band-structure contributions to the first- and second-order elastic shear constants of hexagonal close-packed metals in terms of the normalized energy-wavenumber characteristic of the optimized model potential theory. A method of calculating the internal strain or inner d…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCyclic carboxylic monoimidesMichael K. Hargreaves, J. G. Pritchard, and H. R. DaveCite this: Chem. Rev. 1970, 70, 4, 439–469Publication Date (Print):August 1, 1970Publication History Published online1 May 2002Published inissue 1 August 1970https://pubs.acs.org/doi/10.1021/cr…
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…