Materials Literature
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Molecular dynamics calculations have been used to study structural relaxation and dynamical correlations near the glass transition in the system [Ca(NO3)2]0.4[KNO3]0.6. As in a typical molten salt, the overall structure is determined by charge ordering. However, the radial distribution function for Ca2+ ions is unusua…
The electronic structures of NiMnSb and CrO 2 were calculated using a spin-polarised scalar relativistic linear muffin-tin orbital (LMTO) method. The self-consistent calculations were performed for the observed experimental lattice constants. Cubic NiMnSb (MgAgAs-type structure) and rutile-structure CrO 2 are found to…
Both magnetization and thermal expansion measurements have been made on the same samples of Fe x Co 1- x Si alloys. The magnetization data is analyzed on the basis of the spin fluctuation theory developed by Takahashi to obtain information on the nature of spin fluctuations of this system. We found that concentration…
Detailed measurements of the complex dielectric function ε=ε′−iε″ as functions of frequency between 45 MHz and 20 GHz and concentration c are presented and analyzed for LiCl/H2O solutions. In this frequency range, the dielectric response is due to free water molecules and the response of the bound water occurs at lowe…
The crystal structure of the compound, bis(piperidinium)tetrabromocuprate(II) [(pipdH${)}_{2}$${\mathrm{CuBr}}_{4}$] is monoclinic, space group P${2}_{1}$/c, with a=8.487(2) A\r{}, b=17.225(3) A\r{}, c=12.380(2) A\r{}, and \ensuremath{\beta}=99.29(2)\ifmmode^\circ\else\textdegree\fi{}. The structure consists of isolat…
The c-axis resistivity (${\ensuremath{\rho}}_{c}$) and its temperature dependence of highly oriented pyrolytic graphite have been studied in connection with the characteristic stacking-fault structure. In order to account for the observations, the pioneering theory of Ono on the tunneling conduction through the stacki…
The cyclic process of biosynthesis and degradation of poly(3-hydroxyalkanoate) (PHA) was studied in Alcaligenes eutrophus under conditions of nitrogen-limitation of growth. A. eutrophus cells, which had accumulated poly(3-hydroxybutyrate) (PHB) of 55 wt% content within cells from butyric acid, were transferred into a…
We use simple arguments to fix the range of density of randomly distributed defects over which π electrons in a graphite sheet are strongly localized, but the underlying two-dimensional carbon network remains connected. This ‘‘defeated graphite’’ construct leads to simple structural models of both hydrogenated and unh…
We present valence effective Hamiltonian (VEH) calculations on the optical absorptions of a series of phthalocyanine compounds: the metal-free phthalocyanine molecule, a model system for the lithium phthalocyanine molecule, the metal-free phthalocyanine dimer, and model systems for the lutetium diphthalocyanine and th…
Electron emitters in vacuum microelectronic devices need sharp tips in order to permit electron emission at moderate voltages. A method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm. These tips are formed by oxidation of 5-μm-high silicon cones through exploitation of a kn…
Abstract Owing to enthalpy relaxation, values of the glass transition temperature ( T g ) for partially reacted polymers may depend on the thermal history of samples and the heating rate used for measurements. Use of theoretical relations between T g and the extent of reaction ( x ) of a thermoset must take this fact…
The first measurements are reported for the frequency-dependent (ac) conductivity (real as well as imaginary parts) for various compositions of the bismuth-vanadate glassy semiconductors in the frequency range ${10}^{2}$--${10}^{5}$ Hz and in the temperature range 77--420 K. The behavior of the ac conductivity is broa…
The occurrence of ferroelectricity in smectic-C liquid crystals is discussed and it is suggested that, for this phenomenon to occur, the requirement that the molecules must be chiral is an over-constraint.
Magnesium fluoride(MgF2) and Magnesium aluminate spinel(MgA1204) ceramics for 3-5 micron IR transmission have been developed by a powder processing technique. Their optical, physical, mechanical, and thermal properties have been measured and compared with each other. The transmittance and flexural strength related wit…
In order to provide an accurate basis for the interpretation of the physical properties of this complex incommensurate system, the structure of the room temperature quasi-commensurate phase of barium sodium niobate is determined by taking into account, for the first time, the satellite reflections present in the diffr…
We have measured the effect of pressure on the solid phase epitaxial growth rate of Ge(100) into self-implanted amorphous Ge by using in situ time-resolved infrared interferometry in a high-temperature, high-pressure diamond anvil cell. In the temperature range 300–365 °C, a rate enhancement of more than a factor of 1…
We have imaged for the first time the atomic structure of a quasicrystal using a scanning tunneling microscope. The structure of the decagonal ${\mathrm{Al}}_{65}$${\mathrm{Co}}_{20}$${\mathrm{Cu}}_{15}$ quasicrystal is described by a pentagon-center-decorated pentagonal quasilattice giving strong evidence for a tilin…
In shape-memory alloys a first-order martensitic phase transition is responsible for pseudo-elastic and for ferro-elastic stress-strain relations. To describe this behaviour a modified Landau theory is proposed in which the free energy of the crystal depends on the temperature and on the full strain tensor. The energy…
Abstract Effects of E / P ratio of the EPDM rubber on the flow behavior and morphology of the crosslinkable polyethylene and EPDM blends have been studied as a function of shear rate and processing temperature. High‐ E / P ‐ratio EPDM rubber exhibits high viscosities within the temperature range studied but the extrud…
Abstract New thermoplastic elastomers (TPEs) consisting of a central rubbery polyisobutylene (PIB) and glassy outer cyclopolyisoprene (cy‐PIP) segments have been prepared by living carbocationic polymerization by sequential monomer addition. First the homopolymerization of isobutylene (IB) and isoprene (IP) have been…