Materials Literature
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A review of existing and new structural and Mössbauer data for iron-containing perovskites is presented. A systematic trend between mean M-O bond length and centre shift is determined for Fe2+ and Fe3+ in oxide minerals and silicates, which can be used to determine the valence and site distribution for iron in perovsk…
The presentation gives a brief overview and description of point defects and extended defects that may be considered to arise from clustering or ordering of point defects. Defect chemistry and the relations between defect concentrations and transport properties are exemplified and illustrated by a review of nonstoichi…
A large continuous random-network model with 1296 atoms and periodic boundary conditions has been constructed for amorphous ${\mathrm{SiO}}_{2}$ glass. The atoms in this model are all fully coordinated with an overall small bond length and bond angle distortions. The calculated pair distribution function is in close a…
The effect of steady shear flow on a weakly ordered block copolymer material was examined by in situ small angle neutron scattering. We demonstrate this material undergoes a transition from shear-induced ordering to shear-induced disordering at a fixed temperature above the quiescent disordering temperature. Current t…
The crystal structure of orthorhombic (Pbnm) YAlO3 perovskite has been investigated between 0 and 4 GPa using single-crystal X-ray diffraction in a diamond anvil cell. The compression of the structure is anisotropic with β a = 1.40(4) × 10−3 GPa−1, β b = 1.99(6) × 10−3 GPa−1 and β c = 1.52(5) × 10−3 GPa−1. The dominan…
Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy of Dy2S3-doped As12Ge33Se55 glasses demonstrate that the broad, below-gap PLE mechanism observed previously for rare-earth emissions in Er- and Pr-doped chalcogenide glasses is a general or universal feature of rare-earth-doped chalcogenide gla…
The sulfur vulcanization of polyisoprene accelerated by 2-bisbenzothiazole-2,2′-disulfide (MBTS) was investigated. Rubber compounds were heated in a DSC and removed at various temperatures along the DSC thermal curve. The rubber vulcanizate was analyzed for crosslink density and for residual reactants and extractable…
First-principles electronic structure calculations show that Ga wets the low Miller index surfaces of Al. Consistent with a thermodynamic basis for the observation that Ga causes single-crystal Al to crack along (100) planes, the Ga-covered (100) plane has the lowest surface energy. This represents a compromise betwee…
We review the "Rigid Unit Mode" model that was developed to explain a number of features of framework silicate crystals composed of linked tetrahedral units, but which has implications also for the stability of perovskite structures if the octahedra have some degree of rigidity. The discussion includes the constraints…
Fluorescence dip infrared spectroscopy (FDIRS) is used to probe the effect of a solvent water molecule on intramolecular H-atom tunneling in tropolone. As with the bare molecule discussed in paper I, the FDIR spectrum of the tropolone-H2O complex is recorded in the O–H and C–H stretch regions. Three OH stretch fundame…
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…