Materials Literature
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Abstract Blends of poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPO) and atactic polystyrene (PS) have been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments. Three different compositions were studied by the dynamic mechanical and DSC techniques. T…
Superconductivity persists in several, layered, transition metal dichalcogenide superconductors when the layers are spread apart to accommodate organic molecules between them. These materials are of interest not only because of their two-dimensional character but also because they may provide a means for examining hyp…
Second-order displacive transitions of a type often observed in crystals of perovskite structure are analyzed by means of a phenomenological model employing optical soft-mode and elastic-strain coordinates. Relations connecting spontaneous distortion, soft-mode vibrational frequencies, and elastic constants of a tetra…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical and electron paramagnetic resonance studies of metalloporphyrins and their electrochemical oxidation productsAlexander Wolberg and Joost ManassenCite this: J. Am. Chem. Soc. 1970, 92, 10, 2982–2991Publication Date (Print):May 1, 1970Publication History Publis…
Abstract The nonvolatile products in thermal‐oxidized polypropylene sheet have been quantitatively identified by infrared analysis and chemical reaction. The molecular weight changes with oxidation have been studied by gel‐permeation chromatography. It was determined that there is a functional group at each end of a c…
Hydrostatic-pressure measurements have shown that in PbZr${\mathrm{O}}_{3}$ the antiferroelectric (AFE)-paraelectric (PE) transition temperature ${T}_{a}$ increases ($\frac{d{T}_{a}}{\mathrm{dP}}=4.5\ifmmode\pm\else\textpm\fi{}0.3\ifmmode^\circ\else\textdegree\fi{}\mathrm{K}/\mathrm{kbar}$) whereas the extrapolated Cu…
The X-ray diffraction patterns of the nematic phase of bis-(4′-n-octyloxybenzal)-2-chloro-1, 4-phenylenediamine show major maxima at two diffraction angles. The ones at the larger angle are due to the interaction of neighboring, parallel molecules and the average distance between the long axes of the molecules can be…
1,l0-Phenanthroline-5,6-quinone is prepared from 1,l0-phenanthroline via 5-nitro-1,l0-phenanthroline and 5-amino-1,l0-phenanthroline. It is converted by standard methods into 4,5-diazafluoren-9-one, 4,5-diazafluoren-9-ol,4,5-diazafluorene, and the new heterocyclic system dipyrido[3,2-a:2',3'-clphenazine. These four co…
A relaxation-type calculation of the structure of the dislocation core has been made for the ½ 〈111〉 screw dislocation in b.c.c. crystals, using a variety of central-force potentials. Two stable configurations were found, corresponding to the centre of the dislocation being along either the left-hand or the right-hand…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphorus ligand exchange equilibriums on zerovalent nickel. Dominant role for steric effectsChadwick A. TolmanCite this: J. Am. Chem. Soc. 1970, 92, 10, 2956–2965Publication Date (Print):May 1, 1970Publication History Published online1 May 2002Published inissue 1 May 1970h…
Electron spectra from an extensive series of sulfur compounds have been studied. A correlation has been established between the observed position of inner electron lines of sulfur and structure. The influence of structure on the electron binding energies is discussed in terms of a calculated atomic charge, based on th…
Neutron diffraction measurements and Mössbauer experiments on two Mg ferrites with slightly different cation distribution are reported. A comparison of the magnetic moments of the sublattices measured at 27 °K with the values expected on the basis of the Néel model leads to the conclusion that deviations from this mod…
There is evidence to indicate that some diffusely scattering substances are essentially highly defective lattices rather than made up of small domains diffracting incoherently with respect to each other. Equations have been derived for the diffraction profiles from such lattices; they are of a Cauchy type. Highly defe…
The Raman scattering of polytetrafluoroethylene has been studied as a function of temperature. The 575-cm−1 band is strong below the 19°C transition but weakens above 19°C, while the 595 band is absent below 0°C and increases in intensity with temperature. The 575- and 595-cm−1 bands are attributed to transplanar and…
The absorption spectrum of Tm3+:LaF3 was measured in the region 0.2–2.0 μ which encompasses all but one of the excited states in the 4f12 configuration. Centers of gravity of the observed crystal-field components of each level were computed and used as the basis for determining the free ion energy level parameters. In…
A first-principles self-consistent orthogonalized-plane-wave (SCOPW) energy-band calculation has been performed for cubic BAs using a nonrelativistic formalism and Slater's free-electron exchange approximation. These are the first fully self-consistent energy-band solutions reported for BAs. The imaginary part of the…
Infrared and Raman spectra have been recorded for room-temperature-phase, powdered samples of LiNO 3 , NaNO 3 , KNO 3 , RbNO 3 , CsNO 3 , AgNO 3 , and TlNO 3 . For the trigonal systems, the nitrate pairs LiNO 3 , NaNO 3 and RbNO 3 , CsNO 3 give almost identical spectra. For the orthorhombic systems, AgNO 3 and TlNO 3…
A continuum theory of elastic dielectrics including polarization gradient is obtained as the long-wave approximation of a theory of lattice dynamics for the shell model of cubic ionic crystals. The additional energy associated with the formation and relaxation of a free surface is obtained by considering the unbalance…
Raman spectra of small single crystals of both the trigonal and tetragonal forms of germanium dioxide have been obtained. Frequencies and symmetries of the Raman-active optical phonons are given, and comparison is made with isomorphic $\ensuremath{\alpha}$ quartz and rutile. The temperature dependences of the spectra…
ETTRINGITE (Ca6[Al(OH)6]2(SO4)3.26H2O) occurs as a natural mineral, and is technically important as a hydration product of Portland and supersulphated cements and in its use, as satin white, for coating paper. It forms hexagonal, prismatic crystals which in synthetic material are often highly elongated. Bannister, Hey…