Materials Literature
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The title structure, HgSeO 3 , is isomorphous with those of a series of perovskite-like MSeO 3 compounds and contains corner-sharing HgO 6 octahedra, connecting to form a three-dimensional network, and Se 4+ ions in the cavities of the structure. The octahedron is substantially distorted with Hg-O bond distances betwe…
Ceric potassium nitrate, K 2 Ce(NO 3 ) 6 , was synthesized from the dissolution in nitric acid of active hydrous ceria and potassium nitrate in stoichiometric quantities. Two forms, with hexagonal and monoclinic symmetries, have been isolated. The structures were solved by single-crystal X-ray diffraction analyses. Th…
Dephasing and transient grating experiments in the direct excitonic absorption region of GaSe at low temperatures show that a fast relaxation within the one-dimensionally disordered excitonic band results in band filling being the dominant mechanism of the optical nonlinearity. Correspondingly, we observe a blueshift…
We have performed a systematic theoretical study of the effects of variations in the direction of the incoming electron beam on low-energy electron-diffraction (LEED) intensities for the surfaces Ni{111} and p(2\ifmmode\times\else\texttimes\fi{}2)C-Ni{111}. Large intensity modulations are observed for variations of th…
Photoluminescence (PL) of porous silicon in the redband is studied at temperatures from 15 to 293 K. With increasing temperature, the PL spectrum peak redshifts and the width narrows, while the PL intensity increases until \ensuremath{\sim}70 K and then decreases slightly. At 293 K, the PL at higher emission energy de…
The near-surface regions of high-purity fused silica disks (Corning 7940) were modified by implantation with Bi2+ ions at 160 keV and at room temperature. The glasses implanted with a nominal dose of 6×1016 Bi2+ ions/cm2 at ∼5 μA/cm2 were subsequently annealed in oxidizing and inert atmospheres. The annealing temperat…
Diamonds grown by the temperature-gradient method using a nickel catalyst exhibit a luminescence spectrum that is dominated by a broad band with sharp lines around 2.56 eV. We report optical detection of magnetic resonance of substitutional ${\mathrm{N}}^{0}$ and substitutional ${\mathrm{Ni}}^{\mathrm{\ensuremath{-}}}…
The work function of a single-crystal alumina covered with nanometer-size palladium clusters was measured using the Kelvin probe method. It increases rapidly with coverage and cluster size up to about 2 nm in diameter. The data indicate a formation of interface dipoles caused by charge transfer from ${\mathrm{Al}}_{2}…
Schottky-diode action in thiophene oligomer is investigated by current-density--voltage (J-V) and capacitance-voltage (C-V) measurements. An energy-band diagram is deduced that explains the diode characteristics for both unintentionally and highly doped thiophene oligomers. We conclude that the diode consists of a thi…
We observe a quadratic rise of the absorption coefficient with excitation energy in photoluminescence excitation spectra of porous silicon. Extrapolation to \ensuremath{\alpha}=0 yields an average band gap of microporous silicon about 0.2 eV above the luminescence line. Good agreement is obtained with an estimate of t…
On the basis of phenomenological theory, ferroelectric films with cells finite in three dimensions are studied by considering their practical applications in ferroelectric random-access memory. The lateral size dependence of the Curie temperature and the polarization is obtained and the stability of the ferroelectrici…
Grazing-incidence diffraction from superlattices has been described by a distorted-wave Born approximation. Using the example of a GaAs/AlAs superlattice, the influence of specular interface reflection on the diffraction pattern has been investigated experimentally and well explained by the theoretical treatment. A co…
We report here the magnetic and nonmagnetic electronic-structure calculations of the perovskite oxides LaM${\mathrm{O}}_{3}$ (M=Ti to Ni) and the orthorhombic ${\mathrm{LaScO}}_{3}$ performed using the tight-binding linear-muffin-tin-orbital method. Total-energy calculations for these systems reproduce the magnetic ph…
Advanced spatial light modulators both detect incident light and modulate reflected light. Each pixel may contain multiple photodetectors, a modulator, control circuitry, and signal-processing circuitry. Because each detector and modulator occupies only a fraction of the area of a pixel the optical efficiency of these…
Abstract SiC-SiC composites exhibit a non-brittle behaviour when the fibre-matrix bonding is controlled by the use of an interphase with a layered structure or microstructure, such as pyrocarbon, hex-BN or (SiC-PyC)n multilayers. The best mechanical properties are achieved when there is a balance between the crack def…
The antiferromagnetic state of the title compound has been investigated by the measurements of 1 H-NMR lineshape and nuclear spin-lattice relaxation rate, T 1 -1 , on a single crystal sample. Below the Nèel temperature, T N ∼ 6.7 K, the resonance line was observed to split into three pairs of peaks. The angular depend…
Abstract Perspectives are presented on the development of ceramics and ceramic matrix composites (CMCs) for high-temperature structural components. The emphasis is on design requirements and their role in directing research toward actual products. An important theme concerns the relative roles of fracture toughness an…
In this study a ferroelectric liquid crystal (FLC) monoacrylate (S)-4-(1-ethoxycarbonyl-1-ethyloxy)phenyl 4′-(11-acryloyloxyundecyloxy)biphenyl-4-carboxylate was used. Room-temperature spontaneous polarization of the monoacrylate was measured to be 190 nC/cm2. The monoacrylate was provided with 10% LC diacrylate. Afte…
We have fabricated subwavelength diffractive optical elements with binary phase profiles for operation at 975 nm. The individual surface-relief features of the elements are smaller than the wavelength of light in the material. By modulating the size and spacing of the features we form artificial, gradient, effective i…
The structure of the thermodynamically most stable form of phosphorus pentoxide, o'-(P 2 O 5 )∞, consists of infinite layers built from six-membered rings of three-corner linked PO 4 - tetrahedra, as described in 1964 by Cruickshank [Acta Cryst. (1964), 17, 679-680]. The P― O bond distances and P-O-P bond angles repor…