Materials Literature
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We propose an approach to the calculation of the cohesive and the structural properties of solids. This approach is based on the second theorem of Hohenberg and Kohn and allows one to obtain directly the charge density and the total energy without determining, at the same time, the band structure of the system. The me…
The electronic structures, the charge-density distribution, and the total energies of boron nitrides (BN) in the hexagonal, cubic, and wurtzite structures are studied by first-principles self-consistent local-density calculations. For the ground-state properties, the band structures, the equilibrium lattice constants,…
We report on the first spin- and momentum-resolved photoemission studies on epitaxial f.c.c.-cobalt films above the Curie temperature. In order to obtain a thorough characterization of the electronic states, the photoelectrons have been excited by circularly polarized VUV synchrotron radiation and a vectorial spin ana…
The dielectric, pyroelectric and thermal properties of ferroelectric Bi 2 VO 5.5 (Bi 4 V 2 O 11 ) ceramic have been studied over a temperature range of 300-780 K. The sign of the pyroelectric coefficient is positive at room temperature. The dielectric constant, pyroelectric coefficient and specific heat exhibit anomal…
Self-trapping of holes and excitons in the bulk and on the surface of MgO has been simulated using the self-consistent semi-empirical intermediate neglect of differential overlap method within an embedded molecular cluster model. The authors results suggest that, while holes are not self-trapped in the bulk of MgO, th…
Infrared absorption spectra are presented for freshly evaporated lead phthalocyanine, oxygen doped lead phthalocyanine and material which has been vacuum annealed. The spectra allow characterization of films for utilization in gas sensors and FET structures.
A new phosphor, K 2 Ca 2 (SO 4 ) 3 :Eu, which is more sensitive than the widely used CaSO 4 :Dy has been recently reported. In this paper the authors present results which demonstrate the effect of various preparation procedures on thermoluminescence sensitivity, including the valence state of the impurity and its pos…
The authors give solutions for spin-lattice relaxation in NQR due to magnetic interactions, generalized for non-axial crystal fields with eta not=0. They find analytic expressions for I=3/2 and give numerical solutions for I=5/2, 7/2 and 9/2. They find that the relaxation curves change considerably with eta . Specific…
The authors present a method for the calculation of the scattering of light by a periodic two-dimensional array of spherical particles adsorbed on a uniform dielectric slab. Multiple scattering of light between the particles of the overlayer and between the overlayer and the substrate is taken fully into account. The…
In this paper we report computer simulation results for bulk Gay-Berne fluids with anisotropy parameters κ = 3 and κ′ = 5. Using molecular dynamics simulations in the NVT ensemble, we identify isotropic fluid, nematic and smectic B phases. We observe that the nematic phase is only stable for reduced temperatures T* >…
Abstract A specially designed and characterized oil-free cryogenic UHV experimental system has been used to irradiate pre-thinned orientated copper and molybdenum single crystals at 4.2 and 78 K with very high doses (5 x 1012 to 5 x 1015 ions cm-2) of low-energy (0.2-20 keV) self-ions and xenon ions. Populations of di…
Abstract Constitutive equations are developed that characterize the multiple-slip behaviour of crystalline materials at low temperature. A matrix of instantaneous hardening moduli that relate the rate of hardening on each slip system to all slip-rates is proposed based upon well-known observations and the latent harde…
The frequency-dependent conductivity of glasses is explained in a treatment spanning the range of frequencies, 0< omega < nu ph approximately=10 12 Hz. A large spread of individual relaxation times is assumed. The connection between low frequency AC conduction and DC conduction is their common origin in non-local rela…
It is found that the TiO2 ultrafine particles (UFP) coated with a layer of stearic acid radicals had a significant red shift of their absorption band edge and clear photoluminescence at room temperature (RT), which are in contrast with that of bulk TiO2 and naked TiO2 UFP. It was concluded that these results are relat…
Two 2D quasiperiodic tilings with generalized tenfold symmetry are derived from the lattice A 4 R , the reciprocal of the root lattice A 4 . Both tilings are built from four tiles, triangles in one case, rhombi and hexagons in the other. After a brief description of the tilings and their structures, the authors introd…
ABSTRACT Pertamina/MAXUS Southeast Sumatra Petroleum, Inc. is the largest offshore oil producer in Indonesia. CaCO3 and CaSO4 scaling in and around the submersible pumps of Pertamina/MAXUS' Farida/Zelda reservoir wells led to premature pump failures and costly workovers to bring the wells back into production. Twenty-…
Abstract The mechanical properties such as elastic modulus and stress‐relaxation and spin‐spin relaxation time T 2 from pulse NMR were measured for surface‐oxidized carbon‐black‐filled natural rubber. The extent of reinforcement increased with CB volume percent in the range of 0–30%. At a given CB percent, this quanti…
Abstract Novel 2,2′,6,6′‐tetrabromo‐3,3′,5,5′‐tetramethyl‐4,4′‐biphenol (TBTMBP), and its epoxy derivatives, were synthesized to incorporate the stable meta‐brominated phenol moiety into epoxy resin systems. In electronic encapsulation and laminate applications, epoxy systems derived from TBTMBP have exhibited superio…
Resonance between beams of x-ray waves and electronic transitions from bound atomic orbitals leads to a phenomenon known as anomalous scattering. This effect can be exploited in x-ray crystallographic studies on biological macromolecules by making diffraction measurements at selected wavelengths associated with a part…
A crystal-chemical study of high-aluminium titanites , where X Al =Al/(Al+Ti+Fe 3+ )≥0.25, has been made using single-crystal X-ray diffractometry on four samples from three different rock-types and localities. The first refinement of a natural pure CaTiOSiO 4 titanite in the P2 1 /a space group is also presented. All…