Materials Literature
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High-resolution electron microscopy shows the coexistence of several distinct core structures for coincident-site lattice boundaries in NiO bicrystals near $\ensuremath{\Sigma}=5, (310)$, and $\ensuremath{\Sigma}=13, (510)$, where $\ensuremath{\Sigma}$ is the reciprocal density of coincident lattice sites. Lattice exp…
The authors consider the relationship between Newman's superposition-model formulae and the recently derived transformation matrices S k ( phi , theta ) for the extended Stevens operators. The coordination factors K k q ( theta , phi ) are shown to be the matrix elements (S k -1 ) 0q . A general expression for K k q i…
The use of solution mixing followed by gelation to make ultrahomogeneous glasses and ceramics of various oxide compositions for laboratory experimentation, with first organic and later principally colloidal inorganic, precursors was developed over 30 years ago. Major technologies that use the solution-sol-gel route ha…
Dipole-relaxation parameters for ${\mathrm{Ce}}^{3+}$-${\mathrm{F}}_{\mathrm{int}{}^{\mathrm{\ensuremath{-}}}}$ centers (${C}_{4v}$ symmetry) in ${\mathrm{CaF}}_{2}$ are calculated using the method of ionic thermocurrents (ITC). The data indicate concentration-dependent effects if analyzed using the traditional ITC eq…
The Raman spectrum of ammonia solid I in the lattice and intramolecular regions has been studied at temperatures between 93.6 and 213.5 K. The three most intense lines in the lattice region, one librational and two translational modes, have frequencies and linewidths whose temperature dependence can be explained by an…
Raman scattering from acoustic phonons in a GaAs/${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Al}}_{\mathrm{x}}$As Fibonacci superlattice is reported. Peaks are observed at a set of frequencies that are found to be in good agreement with theoretical predictions based on an elastic continuum model. The…
The distinct variation of the surface enhanced Raman spectral pattern of piperidine under different applied voltages is analyzed with the Wolkenstein’s approximation to reveal its very molecular implication. The calculated effective polarizability derivatives show that there are both chemical and electromagnetic mecha…
An ion-assisted evaporation process is described for the formation of ITO films on substrates that cannot be heated beyond 150 degrees C. Refractive indices and absorption coefficients were measured in the visible part of the spectrum for some of the films. The resistivity of the films varied between 0.7 and 8 x 10(-3…
Site-selective laser spectroscopy has been used to investigate the defect structure of a 0.1 mol % ${\mathrm{Pr}}^{3+}$:${\mathrm{CaF}}_{2}$ crystal. Twenty-three distinct sites have been identified from the fluorescence spectra. Only three of the sites were found to be single-ion sites while the rest were assigned to…
Static electronic hyperpolarizabilities of alkali halide crystals are computed in a local-density-approximation scheme. It is found that the anion nonlinear susceptibilities are extremely sensitive to the crystalline environment while the cation values are not. Calculations using pseudopotentials to represent overlapp…
Structures and optical-absorption edges of ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ glasses prepared by quenching at various temperatures have been studied. Raman scattering spectra show that the medium-range order decreases in the specimens rapidly quenched from temperatures higher than the glass-transition temperature,…
Stable microbubbles are a ubiquitous feature of natural waters, acting as sites for mechanical and acoustical cavitation and nucleii for bubble growth at low gas super‐saturations. Stable microbubble populations that have been determined acoustically in the past are not well explained by existing models of bubble stab…
An exact field theory is presented to describe a system of self-avoiding lattice polymer chains with arbitrary regularly branched architecture. Equivalently, the chains can be viewed as linear and as composed of structural units (monomers) having a chosen shape and size and therefore each occupying more than one latti…
Further insight into the structure and dynamics of amorphous water ice, at low temperatures, was obtained by trapping in it Ar, Ne, H2, and D2. Ballistic water-vapor deposition results in the growth of smooth, approximately 1 x 0.2 micrometer2, ice needles. The amorphous ice seems to exist in at least two separate for…
Molecular dynamics simulation of bulk liquid and glass of long-chain molecules has been performed. The system consists of linear chains of up to 50 spherical segments, each subject to forces due to bond stretching, bending, and torsion, and to nonbonded interaction, according to a truncated Lennard-Jones potential, be…
The transition of PbS from molecular to bulk form has been observed in polymer films. As the particle size decreases the band gap shifts to the blue and eventually approaches the transition energy of the first allowed excited state, X→A, of a PbS molecule. Discrete absorption bands also appear. The electron-hole-in-a-…
A time of flight pulse technique has been used for the measurement of the ratio of radial diffusion coefficient to mobility (D r / mu ) d for electron swarms in helium, argon, neon and krypton. The experimental range for helium and argon is 56.5<E/N<5650 Td (where E/N is the ratio of electrical field to gas number den…
Magnetic and structural properties of as-cast and melt-spun alloys of the RxFeyTiz system with R≡Sm, Nd and 3≤x≤15, 78≤y≤87, and 3≤z≤13 are presented. Two major anisotropic phases with approximate compositions (RTi0.9)15–17Fe83–85 and (R3Ti0.9)15–17Fe83–85 were found to have anisotropy fields greater than 18 kOe and T…
The core electron satellite spectrum accompanying a 1s ionisation in atomic Ne is studied using monochromatised X-ray excited (1487 eV photon energy) photoelectron spectroscopy. Several new 2s-3s satellites are observed and assigned. The shake-off limits for the 2p-np and 2s-ns series are determined and also the conti…
BaTiO 3 positive temperature coefficient of resistance (PTCR) ceramics were prepared using commercially available BaTiO 3 which was doped with 0.4 mol.% Ho to make it semiconducting. The samples were sintered in air at 1320 degrees C and while cooling to room temperature, different samples were annealed at 1220 degree…