Materials Literature
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Optical conductivity spectra of single crystals of the perovskite-type ${3d}^{1}$ metallic alloy system ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{VO}}_{3}$ have been studied to elucidate how the electronic behavior depends on the strength of the electron correlation without changing the nominal number…
The electrical resistivity, magnetization, dilatation and sound velocity have been measured for La 1- X Sr X MnO 3 (0.48≤ X ≤0.90) polycrystals. Observed anomalies in the sound velocity and the dilatation strongly suggest the occurrence of the charge ordering within the Sr concentration range 0.48≤ X ≤0.82. A phase di…
A variety of polyethylenes were investigated over a range of drawing temperatures by the simultaneous measurement of the small- and wide-angle X-ray scattering patterns and the load−extension curve and were all found to undergo a similar sequence of deformation processes under 90 °C. Interlamellar separation was ident…
We predict the formation of GaSe nanotubes from an energetic argument which employs pseudopotential density functional theory methods. The strain energy of GaSe nanotubes is found to be comparable to existing carbon nanotubes. Based on this energetic comparison, we expect GaSe nanotubes with diameters of 40--48 \AA{}…
The effect of noncrystallizable units on the crystallization and melting was studied for two octene copolymers of syndiotactic polypropylene, in an extension of previous investigations on a homopolymer sample with 3% meso diads. Using time and temperature dependent SAXS experiments and DSC, we determined the dependenc…
The transition from microcrystalline to nanocrystalline diamond films grown from Ar/H2/CH4 microwave plasmas has been investigated. Both the cross-section and plan-view micrographs of scanning electron microscopy reveal that the surface morphology, the grain size, and the growth mechanism of the diamond films depend s…
We have studied the electronic structure of Mn impurities in GaAs by Mn $2p$ core-level photoemission spectroscopy. From cluster-model analysis assuming the neutral $({\mathrm{Mn}}^{3+})$ or negatively ionized $({\mathrm{Mn}}^{2+})$ ground state, electronic structure parameters have been obtained. In either case, the…
The layered pnictide titanates ${\mathrm{Na}}_{2}{\mathrm{Pn}}_{2}{\mathrm{Ti}}_{2}\mathrm{O}$, $Pn=\mathrm{Sb}$ and As, display anomalies in the susceptibility and resistivity that have not yet been associated with either magnetic ordering or with structural distortion. Based on local spin-density approximation calcu…
Flyash is an inexpensive material that can reduce the overall cost of the composite if used as a filler for unsaturated polyester resin (PR). Flyash-filled unsaturated polyester resin (FPR) was cast into sheets. The tensile strength, flexural strength, and flexural modulus were determined. Calcium carbonate-filled pol…
Predicted earlier, microcracks on the crystal surface of both finely dispersed $LiYF_4$ powders and single crystals of the Van Vleck paramagnet $% LiTmF_4$ were detected by using the NMR Cryoporometry and Atomic-Force Microscopy technique.
It has been observed that in bulk and polycrystalline thin films of colossal magnetoresistive (CMR) materials the magnetoresistance follows a different behavior compared to single crystals or single crystalline films below the ferromagnetic transition temperature Tc. In this paper we develop a phenomenological model t…
The temperature-dependent electronic structure has been investigated for a single crystal of magnetite $({\mathrm{Fe}}_{3}{\mathrm{O}}_{4})$ by measurements of the optical-conductivity spectrum. Upon the charge-ordering (Verwey) transition ${(T}_{V}=121 \mathrm{K})$, a clear opening of the optical gap (0.14 eV) is obs…
Single crystals of the perovskite-type ${3d}^{1}$ metallic alloy system ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{VO}}_{3}$ were synthesized in order to investigate metallic properties near the Mott transition. The substitution of a ${\mathrm{Ca}}^{2+}$ ion for a ${\mathrm{Sr}}^{2+}$ ion reduces the b…
The optical functions of uniaxial ZnO have been determined using two-modulator generalized ellipsometry, where a single measurement is sufficient to determine the optical functions from appropriately aligned uniaxial crystals. Above the direct band edge $(\ensuremath{\sim}3.3\mathrm{eV}),$ this technique produces the…
The synthesis and structural analysis of a library containing 13 taper- and conical-shaped self-assembling dendrons, 16 dendritic monomers, and their corresponding polymers is reported. Fifteen of these polymers exhibit a well-defined cylindrical shape produced by the self-assembly of their dendritic side groups that…
We report in detail that unlike other materials, carbon nanotubes are so small that changes in structure can affect the Young’s modulus. The variation in modulus is attributed to differences in torsional strain, which is the dominant component of the total strain energy. Torsional strain, and correspondingly Young’s m…
The sol−gel encapsulation of labile biological materials with catalytic and recognition functions within robust polymer matrices remains a challenging task, despite the considerable research that has been focused on this field. Herein, we describe a new class of precursors, based around polyol silicates and polyol sil…
The absence of back scattering in carbon nanotubes is shown to be ascribed to Berry's phase which corresponds to a sign change of the wave function under a spin rotation of a neutrino-like particle in a two-dimensional graphite. Effects of trigonal warping of the bands appearing in a higher order k · p approximation a…
Photoluminescent, undoped ZnO films have been fabricated using spray pyrolysis of zinc nitrate solution. The luminescent films had a polycrystalline hexagonal wurtzite type structure with no preferred orientation. Photoluminescence intensity was critically dependent on substrate temperature during spray pyrolysis and…
Catalytic activities of potassium carbonate and sulfate were studied for the combustion of several carbonaceous grains such as activated carbon, carbon black, graphite, and coal chars (Taiheiyo, Illinoi, and Newlands) by supporting salts either on the carbonaceous surface or a perovskite type oxide. The catalytic acti…