Materials Literature
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The Doi kinetic theory for flows of homogeneous, rodlike liquid crystalline polymers (LCPs) is extended to model flows of nonhomogeneous, rodlike LCPs through a nonlocal (long-range) intermolecular potential. The theory features (i) a nonlocal, anisotropic, effective intermolecular potential in an integral form that i…
We report the characterization of the ceramic SrIn0.1Ti0.9O3 thin film grown by laser molecular-beam epitaxy. The lattice constant is determined to be 0.3948 nm, slightly larger than that of the SrTiO3 substrate. Hall measurement confirms that this film is a p-type semiconductor either below 92 K or above 158 K. X-ray…
The template extraction of two porous clay heterostructures (PCHs), derived from natural montmorillonite (PMH) and synthetic saponite (PSH), has been studied. Extraction in methanol solvent in the presence of cations (H+) removes up to 90% of the templates in a reproducible way without a subsequent calcination step fo…
We have investigated the charge dynamics of the doped carriers in a prototypical double-exchange ferromagnet ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ by reflectivity measurements on cleaved surfaces of the single crystals. Even for wide-band ${\mathrm{La}}_{0.6}{\mathrm{Sr}}_{0.4}{\mathrm{…
The piezoelectric responses of c-axis-oriented Pb(Zr0.53Ti0.47)O3 (PZT) thin films have been studied by measuring the stress-induced charge with an accurate charge integrator. These measurements reveal that the c-axis-oriented PZT films have high values of d33, which are several times those of ceramic materials. The i…
A chemical method has been developed for synthesizing boron nitride nanowires through the reaction of a mixture gas of nitrogen (N2) and ammonia (NH3) over nanoscale α-FeB particles at 1100 °C. Boron content in the product comes from the α-FeB catalyst itself. Transmission electron microscopic image indicates an abund…
The molecular process of crystallization from an oriented amorphous state was reproduced by molecular dynamics simulation for a realistic polyethylene model. The initial oriented amorphous state was obtained by uniaxially drawing an isotropic glassy state at 100 K. By the temperature jump from 100 K to 330 K, there oc…
We report measurements of the thermoelectric power (TEP) S and electrical resistance R of thin films of tangled ropes of single-walled carbon nanotubes. Experiments at 300 K under applied force normal to the plane of the film revealed a $\ensuremath{\sim}10--20 %$ decrease in the four-probe resistance, indicating that…
A systematic Raman study of boron carbonitride (BCN) nanotubes, synthesized by bias-assisted hot filament chemical vapor deposition, is reported. Raman spectra up to the fourth order are observed from the BCN nanotubes. Comparing with pure carbon nanotubes, the Raman bands in BCN nanotubes are broadened and the relati…
La-substituted bismuth titanate [Bi4−xLaxTi3O12(BLT)] films were synthesized using pulsed-laser deposition and ferroelectric fatigue phenomenon was investigated. The internal strain present in the films, which was analyzed through the evaluation of the x-ray diffraction peak, was partially responsible for the fatigue…
Hexagonal polycrystalline boron-nitride (BN) films are synthesized on Si substrates by plasma-assisted chemical-vapor deposition. In the case of BN films thicker than 20 nm, the turn-on electric field of the electron emission decreases with increasing surface roughness. On the other hand, in the case of BN film as thi…
Nematic liquid crystal materials are rod-like molecules that align in a locally common direction called the director. This gives rise to anisotropic properties that are used in electro-optical devices such as displays, which usually consist of a sandwich of material between two substrates. The behavior of the director…
Luminescent Y3Al5O12: Ce3+ [yttrium aluminum garnet (YAG):Ce3+] nanoceramics (5–50 nm) have been prepared through a facile sol-gel pyrolysis route. A blueshift of about 720 cm−1 in the reflectance spectra near the absorption edge can be observed for YAG:Ce3+ nanoparticles (having an average particle size around 5 nm)…
Solid electrolytes with disordered structures, both crystalline and glassy, as well as supercooled ionic melts, exhibit surprisingly similar features in their conductivity spectra, σ(ν). This finding suggests that the dynamics of the mobile ions in the different systems should be governed by similar rules. Examples ar…
BaTiO 3 ( BTO )/ SrTiO 3 ( STO ) artificial superlattices have been made on MgO (100) substrates. The periodicity of the BTO/STO layers in the superlattice was varied from one-unit cell to 125-unit cell thickness. The dielectric constant and its nonlinearity (or voltage tunability) showed similar behavior as the perio…
We propose an analytical interatomic potential for modeling platinum, carbon, and the platinum-carbon interaction using a single functional form. The ansatz chosen for this potential makes use of the fact that chemical bonding in both covalent systems and d-transition metals can be described in terms of the Pauling bo…
Monodispersed ZnS and Eu3+-doped ZnS nanocrystals have been prepared through the co-precipitation reaction of inorganic precursors ZnCl2, EuCl3, and Na2S in a water/methanol binary solution. The mean particle sizes are about 3–5 nm. The structures of the as-prepared ZnS nanoparticles are cubic (zinc blende) as demonst…
Both ``phason'' elastic constants have been measured from Monte Carlo simulations of a random-tiling icosahedral quasicrystal model with a Hamiltonian. The low-temperature limit approximates the ``canonical-cell'' tiling used to describe several real quasicrystals. The elastic constant K2 changes sign from positive to…
Using density-functional theory (DFT) we investigate the incorporation of oxygen directly below the Rh(111) surface. We show that oxygen incorporation will only commence after nearly completion of a dense O adlayer (θ_tot = 1.0 monolayer) with O in the fcc on-surface sites. The experimentally suggested octahedral sub-…
The equilibrium structure and exchange constants of ${\mathrm{CaMnO}}_{3}$ and ${\mathrm{LaMnO}}_{3}$ have been investigated using total-energy unrestricted Hartree-Fock (UHF) and localized orbital configuration interaction (CI) calculations on bulk compounds and ${\mathrm{Mn}}_{2}{\mathrm{O}}_{11}^{14\ensuremath{-}}$…