Materials Literature
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The change of the electronic and magnetic properties as well as the charge-ordering (CO) transition related with lattice dynamics has been systematically investigated for crystals of ${R}_{1/3}{\mathrm{Sr}}_{2/3}{\mathrm{FeO}}_{3} (R=\mathrm{La},$ Pr, Nd, Sm, and Gd) by transmission electron microscopy and measurement…
We have calculated the quasiparticle band gaps of ZnO, ZnS, and ZnSe in zinc-blende structure within the GW approximation using a full random-phase approximation dielectric matrix. The linear muffin-tin orbital basis was used for this calculation and the $3d$ orbitals of the Zn atom were treated as valence band in eve…
Calculations of the electronic structure demonstrate that band gap modification such as opening and closure is easily achieved by radial deformations perpendicular to the tube axis. Deformations open the gap in metallic armchair tubes only if the mirror symmetries are broken, and further distortions greatly enhance th…
Luminescence spectra of lanthanides in the vacuum ultraviolet spectral region have revealed interesting features for ${4f}^{n}\ensuremath{\leftrightarrow}{4f}^{n\ensuremath{-}1}5d$ $(f\ensuremath{-}d)$ transitions. For ${\mathrm{Tb}}^{3+},$ ${\mathrm{Dy}}^{3+},$ ${\mathrm{Ho}}^{3+},$ ${\mathrm{Er}}^{3+},$ and ${\mathr…
This paper described the optical properties of CdSe and CdSe/CdS nanoparticles, synthesized by the microemulsion method followed by refluxing in toluene/methanol (60:1). Both optical spectroscopy and structural characterization (XPS, XRD, and HRTEM) suggested the core/shell structure of CdSe/CdS samples. Most notable…
We analyze the high-electric-field technique designed by Yokoyama and van Sprang [J. Appl. Phys. 57, 4520 (1985)] to determine the polar anchoring coefficient W of a nematic liquid crystal-solid substrate. The technique implies simultaneous measurement of the optical phase retardation and capacitance as functions of t…
Closed cell foams of broad molecular weight distribution commercial polystyrene samples, prepared by expansion of supercritical-CO 2 -swollen specimens, exhibit cell diameters that are ∼3−10 times (19−24 μm) larger than those of foams prepared from polystyrene samples with narrow molecular weight (NMW) distributions (…
We report on the molecular beam epitaxial growth of single-crystalline, stoichiometric ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ and $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ films on MgO(100), using ${\mathrm{NO}}_{2}$ as the oxidizing agent. M\"ossbauer spectroscopy on ${}^{57}\mathrm{Fe}$ probe…
Silicon vapor from a magnetron sputter source was deposited onto highly oriented pyrolytic graphite, resulting in the formation of nanoscale wires. The structures were analyzed by scanning tunneling microscopy. The wires are from 3 to 7 nm in diameter and at least 100 nm long. They tend to be assembled parallel in bun…
The specific heat of $(\mathrm{N}\mathrm{a},\mathrm{C}\mathrm{a}){\mathrm{Co}}_{2}{\mathrm{O}}_{4}$ is measured at low-temperatures to determine the magnitude of the electronic specific-heat coefficient $\ensuremath{\gamma},$ in an attempt to gain an insight into the origin of the unusually large thermoelectric power…
The kinetics of micelle evolution of diblock copolymers from unimers toward the equilibrium state is studied analytically on the basis of consideration of the kinetic equations. The association/dissociation rate constants for unimer insertion/expulsion and micelle fusion/fission are calculated by applying Kramers' the…
In this paper, we propose a mechanism for the formation of single-wall carbon nanotubes (SWCNT's) focusing on the possible transition state when tube formation is initiated. The model explains the generation of SWCNT's from carbon-metal plasmas as well as by the chemical vapor deposition technique. The model qualitati…
The infrared properties of single-wall carbon nanotubes have been measured over 15--5000 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. The sample is a freestanding film composed of purified nanotubes. The temperature dependence of the reflectance is quite small at all temperatures studied (7.8 to 298 K) and no vibration…
We have investigated the dielectric response of a series of {100} fiber-textured (BaxSr1−x)Ti1+yO3+z samples deposited by liquid-source metalorganic chemical vapor deposition onto Pt/SiO2/Si, as a function of the two most commonly varied microstructural parameters: film thickness and Ti nonstoichiometry y. We find tha…
We analyze the influence of defects on conductance, density of states, and localization in ${(N}_{a}{,N}_{a})$ armchair carbon nanotubes within a tight-binding model. Using the transfer-matrix method, we calculate the reflection (related to the conductance) from a sequence of defects and relate its energy dependence n…
We present a noncontact and nondestructive method to measure thermal conductivity in layered materials using micro-Raman scattering. This method was successfully applied to monocrystalline silicon whose thermal conductivity was found to be 63 W/m K at about 550 °C and then applied to porous silicon layers. For a 50 μm…
Infrared reflectance spectroscopy measurements were made on four members of the $M{\mathrm{Fe}}_{4}{\mathrm{P}}_{12}$ family of filled skutterudites, with $M=\mathrm{La},$ Th, Ce, and U. In progressing from $M=\mathrm{La}$ to U the system undergoes a metal-insulator transition. It is shown that, although the filling a…
Laser-arc evaporation of a graphite target has been used to deposit carbon films that exhibit high hardness (45 GPa) and elastic recovery (85%). High-resolution electron microscopy (HREM) and electron energy loss spectroscopy (EELS) were subsequently used to study the microstructure and bonding of the resultant layers…
The low-temperature spin dynamics of doped manganites have been analyzed within a tight-binding model, the parameters of which are estimated by mapping the results of ab initio density-functional calculations onto the model. This approach is found to provide a good description of the spin dynamics of the doped mangani…
Distortions of the oxygen sublattice couple to ${e}_{g}$ orbitals of ${\mathrm{Mn}}^{3+}$ and drive a cooperative Jahn-Teller (orbital ordering) transition in ${\mathrm{LaMnO}}_{3}.$ A simple model for this transition is studied. Without further adjustment, the model predicts the shape and stability of small (anti-Jah…