Materials Literature
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Measurements of the pressure and temperature dependences of the soft-mode Raman spectra of potassium dihydrogen phosphate (KDP) in both the paraelectric (PE) and ferroelectric (FE) phases are reported. The soft-mode response is overdamped throughout the PE phase at atmospheric pressure, but can be made underdamped wit…
Abstract The dielectric functions ϵ | arid ϵ ⟂ of graphite were redetermined by electron energy loss spectroscopy. At 11 eV a strong maximum in Im (ϵ | )is obtained, which is in accordance with earlier electron energy loss experiments, but in disagreement with recent reflectance measurements. A detailed discussion of…
Abstract The luminescence lifetimes in K2Pt(CN)4·3H2O, BaPt(CN)4·4H2O and MgPt(CN)4·7H2O were measured at 1 atom. and higher hydrostatic pressures up to 7.2 kbar at room temperature. Two longer components lengthen anomalously by a factor of ∼ 30 with a decrease in the Pt–Pt distance from 3.50 to 3.16 Å.
Abstract Poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,2‐ethendiyl) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5 diyl‐1,2‐ethenediyl) have been prepared by condensation polymerization using fuming sulfuric acid and different quantities of terephthalic acid (T), fumaric acid (F), and hydrazine sulfate (HS). Homopolymers of F and T a…
SrSiO 3 occurs in two distinct modifications, shown by selected-area electron diffraction to be polytypes. The thermodynamically more stable form, SrSiO 3 (30 Å), has a geometrically near-rhombohedral unit cell, with a = 7.16, c = 30.36 Å on the pseudohexagonal axes, and is an analogue of SrGeO 3 . The other polytype,…
Abstract The crystal structure of sodium hexahydroxoantimonate (V), NaSb(OH)6, has been refined. The previous structure given by Schrewelius was confirmed, but the positional parameters of oxygen atoms were shifted significantly. Both antimony and sodium atoms are surrounded by six oxygen atoms octahedrally. The inter…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNonexponential luminescence decay in hexaureachromium(III)Francesco Castelli and Leslie S. ForsterCite this: J. Am. Chem. Soc. 1975, 97, 22, 6306–6309Publication Date (Print):October 1, 1975Publication History Published online1 May 2002Published inissue 1 October 1975https:/…
A detailed semiempirical molecular orbital calculation is presented for computing the energy levels of various luminescent centers in the antimonates. In order to interpret the excitation spectrum of the nondoped compounds, the MO calculations are carried out on two clusters: (SbO6)7− and (SbO6)9−. In the first one, t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLow-melting nematic phenyl 4-benzoyloxybenzoate liquid crystalsJ. P. Van Meter and A. K. SeidelCite this: J. Org. Chem. 1975, 40, 20, 2998–3000Publication Date (Print):October 1, 1975Publication History Published online1 May 2002Published inissue 1 October 1975https://pubs.a…
In many of their compounds the transition metals have covalence 9, forming nine bonds with use of nine hybrid spd bond orbitals. A set of maximum-valence single-bond radii is formulated for use in these compounds. These radii are in reasonably good agreement with observed bond lengths. Quadruple bonds between two tran…
Abstract Full and reduced charge smectite saturated with Na(I), Ca(II), Cu(II), or tetralkylammonium ions were swollen by a series of solvents of various bulk physical properties. In the full charge smectites, swelling occurred in all solvents regardless of the exchange ion or the initial water content. Charge differe…
The electric field induced second harmonic coefficient has been measured in glass. We have concluded that the nuclear contribution is significantly smaller than the electronic contribution, and that this third order effect in glass cannot be neglected when measuring the molecular hyperpolarizabilities of most organic…
A new, general and convenient technique is presented for determining the burgers vectors of (DSC) grain boundary dislocations and it is applied to hexagonal lattices. A general rotation between two hexagonal lattices may be expressed as a disorientation by a suitable reindexing of the two lattices, and it is shown how…
Abstract We report that aliphatic primary and secondary amines completely solubilize crosslinked silicone resins and rubber compositions at room temperature. The solubilization is attributed to nucleophilic cleavage of SiO bonds by amines, which apparently occurs selectively at crosslinking sites. The selectivity may…
The anodic behavior of AISI 304 stainless steel in 1M hydrochloric acid solution at 25 C has been studied at different electrode potentials under static conditions and during straining at 40%/minute. From the potential-time curves, current-time curves, and net anodic current densities, it is concluded that a film form…
Davies and Jones have shown that if the configurational state of a liquid is determined by two or more order parameters that freeze in at the glass transition temperature Tg(P), the Ehrenfest relation, r=ΔβΔCp/TV (Δα)2=1, valid if there is one such parameter, is converted to an inequality r?1. DiMarzio has shown corre…
Abstract The changes in conformation undergone by α‐gelatin molecules on quenching aqueous solutions to below the temperature at which they can gel have been monitored by nuclear magnetic resonance and dielectric relaxation techniques. The relative rates of these conformational transitions are compared with changes in…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRearrangement of N-substituted porphyrins. Preparation and structure of homoporphyrinsH. J. Callot and Theophile TschamberCite this: J. Am. Chem. Soc. 1975, 97, 21, 6175–6178Publication Date (Print):October 1, 1975Publication History Published online1 May 2002Published iniss…
Abstract The kinetics of initiation of the polymerization of 2,2,5,5‐tetramethyl‐1‐oxa‐2,5‐disilacyclopentane ( 2 ) with sodium phenyldimethylsilanolate 1a and two of its phenyl substituted derivatives was investigated as model reaction for studying the initiation and crosspropagation steps in anionic polymerization o…
R. H. Ritchie, C. J. Tung, V. E. Anderson, J. C. Ashley, Electron Slowing-Down Spectra in Solids, Radiation Research, Vol. 64, No. 1, Symposium on the Distribution of Secondary Electrons from Ionizing Collisions (Oct., 1975), pp. 181-204