Materials Literature
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It has been reported that SrTiO₃/ becomes ferroelectric below about 50 deg K. When SrTiO₃ is compared with well known ferroelectrics such as BaTiO₃, remarkable contrasts are found in their dielectric properties. The dielectric constants are examined in three directions: STA110!, STA111!, and STA100!. (W.D.M.)
The density, refractive index, molar refractivity, and infrared absorption spectra of soda aluminosilicate glasses containing up to 34.8 wt% alumina have been determined. Changes in these properties with composition can be explained by existing theories which assume that the aluminum ions form only A10 4 tetrahedra wh…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTHE ADSORPTION-FLOCCULATION REACTIONS OF A POLYMER WITH AN AQUEOUS COLLOIDAL DISPERSIONThomas W. Healy and Victor K. La MerCite this: J. Phys. Chem. 1962, 66, 10, 1835–1838Publication Date (Print):October 1, 1962Publication History Published online1 May 2002Published inissue…
The possibility of the rotation of a subgrain with respect to its neighbors as a natural process during recrystallization is analyzed thermodynamically and kinetically. It is found that it is energetically possible if the direction of rotation favors the elimination of low-angle boundaries over that of high-angle boun…
Static pressure apparatus has been developed which is capable of pressures up to 200 kbar and transient temperatures up to about 5000°K, using an electric flash‐heating technique. At pressures above about 125 kbar and temperatures in the 3000°K range it is found that graphite spontaneously collapses completely to poly…
Abstract An investigation has been made of the friction and wear of hard solids such as sapphire (Al2O3), rutile (TiO2), TiC, SiC, diamond and fused silica (SiO2) sliding on metal surfaces at very high speed (700 m/s). It is shown that hard solids can undergo extensive wear when rubbed against metals of much lower har…
The process of variable transmission in silicate glasses has been accomplished by optically pumping color centers by electron transfer from europium (II) or cerium (III) which absorb sunlight at higher energies than the color center. Absorbed energy quickly pumps the visible color center band to a maximum. Upon remova…
Reported values of the $K$ x-ray fluorescence yield of argon lie in two distinct groups, viz., low values (about 0.07) and high values (about 0.13). A new measurement herein reported gives 0.14\ifmmode\pm\else\textpm\fi{}0.014. This measurement was made from the "escape peak" in the pulse-height distribution of a flow…
Two photosensitive electron paramagnetic resonance signals A and B are found in self-activated ZnS phosphors of polycrystalline form. Both these signals appear at 77°K when illuminated with uv light, and can be quenched with visible light of longer wavelength. The center responsible for the A signal is a hole trap and…
An appreciable number of magnetic materials with the spinel structure exhibit tetragonal symmetry, rather than cubic, in their x-ray diffraction patterns. Because of the distortion, five different nearest-neighbor exchange interactions are possible, so that four ratios ($t, u, v, \mathrm{and} w$) amongst these interac…
Using the specific heats of completely crystalline polyethylene as a basis, the vibrational spectrum is discussed. The vibrational spectrum is found to consist of three completely separate parts. (A) The high-frequency CH2-stretching vibrations between 2850 and 2930 cm—1 which contribute little to the specific heat be…
Data for the specific heat of polyethylene as a function of crystallinity are collected from 1° to 420°K. Specific heats, entropies, and enthalpies of the completely amorphous and crystalline polyethylene are extrapolated. The glass transition is located for the amorphous at 237°K with a ΔCp of 2.1 cal deg—1 (mole CH2…
A study has been made of the photoemission from metal films evaporated on a freshly cleaved silicon surface, the silicon-metal junction acting as a collector. Plots of the photoemission as a function of photon energy yield values for the height of the potential barrier at this junction of 0.795\ifmmode\pm\else\textpm\…
Observations of the freezing behavior of droplets of a linear polyethylene (Marlex-50) suspended in an inert medium have been made. It is possible to cool such suspensions of molten droplets to 85°—87°C before the majority of the droplets freeze, provided precautions are taken to minimize nucleation by the vessel wall…
The photoconducting compound SbSI was found to be ferroelectric with a Curie point at 22\ifmmode^\circ\else\textdegree\fi{}C. It has a high spontaneous polarization of ${P}_{s}=25\ensuremath{\mu}\mathrm{C}/{\mathrm{cm}}^{2}$ and a small coercive field strength of ${E}_{c}=100$ V/cm at 0\ifmmode^\circ\else\textdegree\f…
The s urface pressure-area isotherms at 24.5 C a re r eported for poJy (et hylene adipate) , poly(trimethyle ne adipate) , and poly(propylene adipate), spread as monolaye rs at a iraqueous interfaces. The monolayers were spread on di st ill ed water a nd 0.01 N I-I Gl, using b enzene, chlorofor m, and acetone a s sp r…
A new band system in ZnH, with its corresponding analogue in ZnD, at 2426.46 Å (0, 0 band) has been observed and analysed. The analysis showed that the transition is of the C 2 Σ → X 2 Σ type. The rotational lines observed (in absorption) are very diffuse and therefore it is concluded that the upper state is predissoc…
An experimental study on the thermal glow luminescence in plastically deformed KCl crystals has been carried out. The thermal glow curves of plastically deformed crystals become simple and similar irrespective of the origin of crystals, in contrast with the case of “as-cleaved” crystals. In the case of ultra violet il…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal Analysis of Phosphor Raw Materials.R. C. Ropp and M. A. AiaCite this: Anal. Chem. 1962, 34, 10, 1288–1291Publication Date (Print):September 1, 1962Publication History Published online1 May 2002Published inissue 1 September 1962https://pubs.acs.org/doi/10.1021/ac60190…
The nuclear quadrupole coupling constant of Na 23 in sodium nitrite. NaNO 2 . has been investigated between 18 °C and 215 °C. Below the transition temperature (163 ± 2)°C the asymmetry parameter η= (φ xx — φ yy )/φ zz decreases with increasing temperature and goes to zero at the transition point. Above 163 °C η is neg…