Materials Literature
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Much more intense ultraviolet (UV) and blue upconversion fluorescence of Tm3+ was observed in a new stable fluoroindate glass compared with other fluoride or oxide glasses. The intense upconversion intensity and high thermal stability of these fluoroindate glasses indicate a high possibility for the realization of a U…
Structural characteristics of liquid silicon (l-Si) have been examined by molecular-dynamics calculations using the Tersoff empirical potential. Generated l-Si possesses a broad distribution of the coordination number dominated by the sixfold coordination. The average bond length increases with the coordination number…
The s,p-d exchange interaction in Cr-based diluted magnetic semiconductors was studied by means of polarized magnetoreflectance and magnetization at T=2 K. The exchange constant ${\mathit{N}}_{0}$\ensuremath{\alpha}-${\mathit{N}}_{0}$\ensuremath{\beta} for four different zinc chalcogenides (${\mathrm{Zn}}_{1\mathrm{\e…
Using a combination of junction capacitance techniques, we measure both the a-${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{C}}_{\mathit{x}}$:H/c-Si conduction- and valence-band offsets in a Schottky diode heterostructure sample composed of a sub-\ensuremath{\mu}m-thick layer of intrinsic hydrogenated…
Using a previously proposed diagrammatic approach for the calculation of the renormalized polarizability of spherical inclusions in a homogeneous matrix we obtain an effective dielectric response of a composite of nonpercolating inclusions taking into account a continuous distribution of sizes of the spheres. We apply…
Using 31 P-nuclear magnetic resonance (NMR), low-energy spin excitations are investigated in both (VO) 2 P 2 O 7 and VO(HPO 4 )0.5H 2 O, in which V 4+ ( S =1/2) ions take ladder and dimer (isolated pair) configurations, respectively. Temperature ( T ) dependences of Knight shift ( K ) and nuclear spin-lattice relaxati…
Polymer dispersed liquid crystal (PDLC) materials based on poly(polyethyleneglycol methacrylate) are prepared by ultraviolet light induced polymerization. Microphase structure of PDLC films is observed by scanning electron microscopy. It reveals that reversed morphology type PDLC is obtained. The liquid crystal (LC) i…
Thick p-type porous 6H SiC layers were fabricated by anodization of p-type 6H SiC bulk crystals in dilute HF. Striking differences are observed in the reststrahl region room-temperature reflectance of these porous layers compared to that of bulk 6H SiC crystals. Instead of the single broad band reflectance spectrum ty…
We present a model of tetrahedral amorphous carbon (with density 3.0 g ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$) obtained from self-consistent plane-wave (Car-Parrinello) methods. This model is closely related to one we presented earlier [Phys. Rev. B 49, 16 415 (1994)], except for an even greater tendency toward ${…
Glass beads were encapsulated by grafted polymers: polybutylacrylate and polystyrene. Grafting was performed by the polymerization initiated from the particle surface with preliminary adsorbed polyperoxide initiator. Grafting procedure and properties of grafted film were studied using model substrates: powders, plates…
We analyzed the photoluminescence (PL) mechanisms of porous silicon, and in particular, the origin of the PL high quantum efficiency (QE) at room temperature. For this we used postformation treatments, anodic oxidation, and hydrofluoric acid (HF) etching (known for their strong QE enhancement effect) correlated with a…
Electrical switching properties of Ge-As-Te glasses have been investigated over a wide range of mean coordination numbers (〈r〉) in a single composition tie line. The results obtained clearly indicate the modulation of the composition dependence of switching fields by network topology. Distinct change is observed in th…
Photothermal deflection spectroscopy (PDS) is used to study subgap optical absorption in chemical vapor deposited (CVD) diamond films. The high PDS sensitivity over a broad investigated spectral range enabled the investigation of the main defect structure in CVD diamond upon changing the deposition conditions. All fil…
Twenty elements were codeposited with carbon in an arc discharge between graphite electrodes. The majority of them were evaporated from composite anodes that contained the elements or their oxides stuffed into central bores in the graphite rods. The deposits, found in the soot at the reactor walls or as slag at the ca…
It is shown that charge transport in SiC ceramics includes atomic mechanisms as well as phenomena which depend on the microstructure of the material. Both aspects are revealed by the analysis of temperature-dependent dc and ac measurements. The complex dielectric function (DF) of boron-doped SiC ceramics with various…
We carry out a calculation of the phonon-drag contribution ${\mathit{S}}_{\mathit{g}}$ to the thermoelectric power of bulk semiconductors and quantum well structures using the balance equation transport theory extended to weakly nonuniform systems. Introducing temperature-, wave-vector-, and mode-dependent phonon rela…
Four aluminum-jacketed, fluorine-doped silica clad optical fibers with silica core materials fabricated by differing technologies were subjected to sequential 60Co-γ ray and fission-reactor irradiations (at ∼20 and 40 °C, respectively), an intervening isothermal anneal (∼20 °C), and a final isochronal anneal (to 600 °…
The isotropic–nematic (I-N) phase transition in hard ellipsoid fluids has been studied by computer simulation, using the Gibbs–Duhem integration technique introduced by Kofke; and theoretically, using Onsager theory and the Parsons–Lee improvement. In the simulations, the I-N coexistence line is mapped out in the P–x…
Polycrystalline Bi4Ti3O12 thin films having layered perovskite structure were fabricated by metalorganic solution deposition technique on both Pt-coated Si and bare Si substrates at a temperature as low as 500 °C. The effects of post-deposition rapid thermal annealing on the structural and electrical properties were a…
Thin films of Si nanoclusters passivated with oxygen or hydrogen, with an average size of a few nanometers, have been synthesized by thermal vaporization of Si in an Ar buffer gas, followed by subsequent exposure to oxygen or atomic hydrogen. High-resolution transmission electron microscopy and x-ray diffraction revea…