Materials Literature
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Sputtered films of ferroelectric Bi4Ti3O12 have been prepared by using targets containing excess Bi to compensate for loss of Bi in the deposition process. Epitaxial growth has been achieved on MgO and epitaxial Pt substrates. Studies of dielectric properties suggest that the sputtered films are suitable for use in hi…
The phonon dispersion curves of Si are calculated from the dielectric screening theory using approximations based on Phillips's bond-charge model for covalent crystals. The off-diagonal ($K\ensuremath{\ne}{K}^{\ensuremath{'}}$) elements of the inverse dielectric function ${\ensuremath{\epsilon}}^{\ensuremath{-}1}(\mat…
The luminescence of Tb3+-activated CeF3, CePO4, CeBO3, and CeAlO3 has been investigated. Energy transfer from the Ce3+ host lattice to the Tb3+ ion occurs by Ce3+–Ce3+ and Ce3+–Tb3+ transfer. From a study of the Ce3+ luminescence in the analogous La compounds it can be concluded that the probability of the former tran…
An Auger electron spectrometer for studies of solid surfaces which is considerably more sensitive than currently used instruments has been developed. The greatly improved signal-to-noise ratio of the spectrometer made it possible to display the 0–1000 eV Auger spectrum on an oscilloscope at a scanning rate of 20 000 V…
A luminescence band with a half-width of about 0.6 eV at liquid-nitrogen temperature, which can be excited by uv light and x rays, has been observed in irradiated and additively colored MgO crystals at 3.13 eV. By combining ESR and optical studies, this emission band has been identified as due to ${F}^{+}$ centers (ox…
The fluorescence and absorption spectra of trivalent europium ions in glass were measured and compared with the spectra of single crystals of ${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$: Eu. It was determined that there is a great similarity between the optical properties of the rare-earth glasses and rare-earth sesquioxide…
The absorption spectrum of cerium-doped Ca${\mathrm{F}}_{2}$ has been observed at several temperatures. When the cerium is reduced to the divalent state at room temperature, the absorption spectrum of ${\mathrm{Ce}}^{2+}$ is found to be unstable against thermal decay or bleaching by visible light; furthermore, this sp…
Two structural phase transitions in PrAl${\mathrm{O}}_{3}$ have been observed at 205 and 151\ifmmode^\circ\else\textdegree\fi{}K, and determined to be of first and second order, respectively. The electric and magnetic susceptibilities, measured as a function of temperature, exhibit a step discontinuity at the 205\ifmm…
The magnetic moments in the ordered Y${\mathrm{Co}}_{5}$, ${\mathrm{Y}}_{2}$${\mathrm{Co}}_{7}$, and Y${\mathrm{Co}}_{3}$ intermetallic compounds with closely related crystal structures have been investigated on single crystals using the polarized-neutron-diffraction technique. By assuming that only the cobalt atoms h…
It is shown that Fowler's hypothesis to explain photoemission from metals is not necessary to obtain a spectral dependence of quantum yield near threshold that varies as ${Y}^{\frac{1}{2}}\ensuremath{\propto} (h\ensuremath{\nu}\ensuremath{-}e\ensuremath{\varphi})$. It is not possible to distinguish between a Fowler di…
A calculation is presented of the dissipative part of the wave-number-dependent, high-frequency dielectric tensor of a free-electron gas. The calculation, which is exact to lowest order in ${k}^{2}$ and ${r}_{s}$, includes dynamical correlational (screening) effects which lie outside the random-phase approximation (RP…
The paramagnetic resonance of two tetragonal nickel spectra in the cubic phase of SrTi${\mathrm{O}}_{3}$ has been investigated below the structural phase transition at 105\ifmmode^\circ\else\textdegree\fi{}K. Both spectra show the same rotation angle measured from the tetragonal directions as the iron-oxygen vacancy c…
The effect of pressure up to \ensuremath{\simeq}45 kbar on the N\'eel temperature ${T}_{N}$ of magnetite (${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$) was measured. ${T}_{N}$ increases linearly over this range with slope $\frac{\ensuremath{\partial}{T}_{N}}{\ensuremath{\partial}p}=2.05\ifmmode\pm\else\textpm\fi{}0.10\ifmmod…
A MEANS OF REINFORCING THE DECK CONCRETE FOR CONTINUITY AND CRACK CONTROL IS AUXILIARY PRESTRESSING. PART OR ALL OF THE DECK REINFORCEMENT IS REPLACED BY LONG PRECAST PRISMS OF CENTRALLY PRESTRESSED CONCRETE. WHEN THIS IS DONE, LIMITED PAST EXPERIENCE HAS SHOWN THAT THE CAST-IN-PLACE CONCRETE SURROUNDING THE PRECOMPRE…
A class of galactose-resistant mutants has been derived from strains of Salmonella typhimurium which are defective in uridine diphosphoglucose-4-epimerase. Resistant strains are phenotypically similar to parent organisms but do not lyse in the presence of galactose. Low levels of functional epimerase can be detected i…
EPR data were determined at 4.2°K for Ru3+ impurities located at the octahedral sites of two lutetium garnets and yield the following g values: g‖ = 3.161, g⊥ = 1.136 in LuGaG and g‖ = 2.907, g⊥ = 1.286 in LuAlG. From these data the dependence of the trigonal field parameter υ on polar angle is derived and represented…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal and neutron irradiation effects on the rate of racemization of d-K3Cr(C2O4)3.2H2O in the solid stateDhirendra M. Chowdhury and Gordon McLeod HarrisCite this: J. Phys. Chem. 1969, 73, 10, 3366–3369Publication Date (Print):October 1, 1969Publication History Published o…
An empirical relation, θD = 32·37 (Ws/MV 2/3)1/2, connecting the Debye temperature (θD) and the formation energy of Schottky defects in alkali halides (Ws ), is found and this relation is used for predicting the formation energy of Schottky defects in various alkali halides. The predicted values for Ws are compared wi…
Abstract Die Phasendiagramme PbSPbJ 2 , PbBr 2 und PbCl 2 wurden röntgenographisch und mittels Differentialthermoanalyse untersucht. Bei den Systemen mit PbJ 2 bzw. PbBr 2 handelt es sich um pseudobinäre peritektische Systeme mit den ternären Verbindungen Pb 5 S 2 J 6 bzw. Pb 7 S 2 Br 10 . Einkristalle davon wurden…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotolytic rearrangement and halogen-dependent photocylization of halophenylnaphthalenes. IIWilliam Arthur Henderson Jr., R. Lopresti, and Arnold ZweigCite this: J. Am. Chem. Soc. 1969, 91, 22, 6049–6057Publication Date (Print):October 1, 1969Publication History Published on…