Materials Literature
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The elastic constants of the cubic perovskite KZnF 3 have been measured from 4 to 300 K. Heat capacity data, C p , and elastic constants have been analysed and compared with the predictions from the lattice dynamics within a rigid-ion model. Phonon dispersion curves at different temperatures, heat capacity and Debye t…
Abstract Crystal structures and electrical properties of radical‐cation salts of the chiral organic donor TMET ( S , S , S , S ,‐bis‐(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf , AsF , SbF , I (incommensurate), and 3:2 with tetrahedral anions BF − 4 ,…
Copolymers of azo dye substituted acrylic monomer and methylmethacrylate are synthesized and their third-order nonlinear optical susceptibility χ(3) is evaluated using the third harmonic generation Maker fringe method. The χ(3) is 1.26×10−12 esu at 25.9 mol % azo dye monomer content in the copolymer. It is also shown…
The predominance of nickel and vanadium porphyrins, over other metalloporphyrins in the geosphere may be explained by taking into account four factors: the abundances of the metals, and their environment within the sediments and/or the water column, the stability of the nitrogen-metal bonds, and the lability of the br…
Lamellar eutectics only grow in steady state over a small range of melt compositions between the two solidus lines of a binary phase diagram. Outside this range their growth exhibits a rich dynamical behavior. A random-walk model is constructed to simulate eutectic solidification of a thin film and applied to study th…
Polyurethanes have become the most valuable implantable elastomers for uses requiring toughness, durability, biocompatibility and biostability. They are inherently stable in the body environment. However, physical and chemical changes may be effected by conditions of processing, fabrication, use or interactions with o…
The response to electron bombardment of highly stressed Kapton-HTM, TeflonTM (polytetrafluoroethylene), and linear high-density polyethylene is investigated. Evidence is presented for electron induced crack initiation and crack growth. Calculations show that the electron exposures used in these experiments are suffici…
The effects of electron radiation and elevated temperature on the matrix dominated, cyclic response of standard T300/934 and a chemically modified T300/934 graphite-epoxy are characterzed. Both materials were subjected to 1.0 x 10 10 rads of 1.0 MeV electron ir radiation, under vacuum, to simulate 30 years in geosynch…
This paper deals with the irradiation effects on the thermal shock resistance Δ = σtk/Eα (σt : tensile strength, k: thermal conductivity, E: Young's modulus, α: thermal expansivity) and the thermal shock fracture toughness ∇=KIck/Eα (KIc : fracture toughness value of mode I) in addition to other mechanical properties…
It is shown that accurate x-ray photoemission spectroscopy values of the valence band offsets ΔEv for Ge/GaAs(110), GaAs/ZnSe(110), and Ge/ZnSe(110) vary linearly with the minimum band-gap difference and obey the simple scaling relation, ΔEv/ΔEg(min)=3/4. This empirical observation is compared with the predictions of…
Thermal conductivity, specific heat capacity and complex dielectric constant of PSN ceramic have been measured from 0.1 K up to 100 K. The thermal conductivity increases after poling of the sample but no influence of an applied electric field on the specific heat and the dielectric constant has been detected. Below 0.…
Abstract The behaviour of electrical conductivity of four ferrite semiconductor systems viz., Li‐Ni, Mn‐Mg, Co‐Zn and Ni‐Zn having different compositions has been studied in the vicinity of magnetic transformation temperature. Contrary to the predictions of an empirical formula (P ARKER 's) all the ferrites under inve…
Abstract A molecular theory for small‐angle neutron scattering from polymer mixtures is reviewed and extended to consider multiphase polymer systems such as block copolymers and their blends with homopolymers. Methods are developed for the isolation of scattering functions for individual components in these blends. Th…
Abstract Thermodynamic information is utilized to study the width of the zinc ferritemagnetite phase field, and to establish the oxygen fugacity in equilibrium with this solid solution. Information is provided for the specification of the phase boundaries and for the particular oxygen fugacity that corresponds to the…
We employ mean field theory to study the phase behaviour of nematics in the presence of arbitrary electric and magnetic fields. A rotationally invariant pseudopotential is used. If the molecules have cylindrical symmetry, the most general situation is equivalent to perpendicular electric and magnetic fields. The numer…
Abstract The influence of diluent composition on the internal structure of porous copolymers of 1,4‐di(methacryloyloxymethyl)naphthalene (1,4‐DMN) and divinylbenzene (DVB) was studied. A set of copolymers containing 0.5 mole fraction of 1,4‐DMN and 0.5 mole fraction of DVB obtained in the presence of various amounts o…
The need for more efficient transformer core materials, due to increased recognition by electric utilities of the costs of system losses, has spurred the development of amorphous alloy usage in power transmission and distribution transformers. Amorphous alloy core fabrication, as it relates to single phase distributio…
Summary. The relationship between environmental archaeology and diatom analysis, a well established technique in palaeoecology, is explored. The development of diatom analysis for palaeoenvironmental reconstruction is briefly considered and flow diagrams are presented to illustrate laboratory techniques. Examples of r…
Surface Raman scattering (SRS) by electron-hole pairs at metal surfaces has been analysed theoretically and experimentally. Our analysis, performed for a planar surface, predicts for the SRS intensity a broad peak at low temperatures, due to the excitation of e-h pairs by the polariton field penetrating into the metal…
Abstract This study is concerned with some kinetic features of the reaction of n‐butyl isocyanate with poly(vinyl alcohol) without any catalyst and using triethylene diamine as catalyst. The structure of the resulting polymers was determined by means of IR, 1 H‐ and 13 C‐NMR spectroscopy as well as by chemical analysi…