Materials Literature
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The result of a combined study of the absorption and photoluminescence (PL) from high-optical-quality free-standing porous Si films is presented. These films, which have a scattering loss less than 10%, allow unambiguous, detailed study of the system's absorption edge and, in addition enable us to correlate the absorp…
Several theoretical studies of the stability of (111)-terminated ionic crystals with the NaCl structure have predicted that the crystal Madelung energy can be stabilized by a simple surface reconstruction. However, previous attempts to grow (111)-terminated crystals have resulted in either unreconstructed or faceted s…
Low pressure sputter atom deposition is a commonly used method for coating and trench filling in semiconductor chip manufacturing. In this paper we present a selfconsistent simulation of this process in which both the sputtered atoms and the background gas are computed by means of the Direct Simulation Monte Carlo (DS…
The two-dimensional melting transition of charged polystyrene spheres in aqueous colloidal suspension has been studied by molecular dynamics simulation of a screened Coulomb system. Some central predictions of the Kosterlitz–Thouless–Halperin–Nelson–Young theory of defect-mediated melting are confirmed, such as an app…
We have employed reflection high energy electron diffraction (RHEED) and high resolution transmission electron microscopy (HREM) to study Cu films grown on hydrogen terminated Si(100) and Si(111) substrates by molecular beam epitaxy. X-ray diffraction and RHEED studies indicate 〈100〉Cu growth on Si(100) and 〈111〉Cu gr…
The conformational and thermodynamic behavior of chain molecules tethered to a planar surface are studied for a variety of solvent qualities with a recently developed single-chain mean-field theory. The lateral pressure isotherms calculated from the theory for chains of n=50 segments show very good quantitative agreem…
The electronic structure and properties of the noble-metal monoxides, PdO, PtO, and AgO have been determined by the full-potential linearized augmented-plane-wave (FLAPW) and full-potential linear-muffin-tin-orbital (FLMTO) methods. The calculated band structures show PdO and PtO to be poor metals with very low densit…
Spectroscopic properties, ionization potentials, dissociation energies, and the 1A1−3B1 energy separations were determined for SnX2 and PbX2 (X=Cl,Br,I). The methods of calculations employed were complete active space self-consistent field (CASSCF) followed by multireference single+double configuration interaction (MR…
Pure single crystals of barium titanate have been synthesized and the structure refined using the atomic coordinates of Burbank & Evans [Acta Cryst. (1948), 1, 330-336]. The short Ti-Ti distance in the face-sharing Ti 2 O 9 group was determined to be 2.690 (4) A, which is significantly shorter than in other barium tit…
Metastable liquid water, obtained by heating its hyperquenched glassy state above its glass→liquid transition temperature, crystallizes to cubic ice. Kinetics of this crystallization has been studied by Fourier transform infrared spectroscopy by determining the change in the spectra of stretching vibrations of the dec…
The diffuse scattering of conduction electrons at a rough surface has a considerable contribution to the resistivity of thin films, which is well known as the classical size effect. We have separated this contribution from other scattering mechanisms such as the phonon and bulk defect scattering by the following proce…
The effect of the cluster surface on the ground state electronic properties of CdSe nanoclusters is calculated using a tight-binding method. The calculation of optical matrix elements between selected surface and interior states is described. We find that the density of states is strongly dependent on the nature of th…
Room temperature 31P magic angle sample spinning (MAS) nuclear magnetic resonance (NMR) is used to study the phosphine chalconide species coordinating the surface of CdSe nanocrystallites. Two surface species are identified: trioctylphosphine oxide (TOPO) and trioctylphosphine selenide (TOPSe). The TOPO coordinates Cd…
We present strong experimental evidence suggesting that we have synthesized the \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ phase. This is a material predicted by theory to have bulk moduli comparable to diamond. Thin films containing small crystals were deposited on Si and Ge wafers by rf diode sputtering…
In this paper we show that (1) for graphene tubules an axial magnetic field can induce a semimetal-semiconductor transition periodically at zero bias. This is an Aharonov-Bohm-type effect and is generally true for thin cylindrical conductors; (2) the Landauer approach can be used to estimate the conductance of individ…
Two methods for relating different carbon tubules are described. A single graphene ribbon of infinite length but finite width can be coiled to form an infinite set of tubules, each of which has a unique pitch or helicity. This maps in a one-to-one fashion the translation/rotation operations of the group of each tubule…
Transport properties of direct-gap semiconductors are calculated in order to find the best thermoelectrics. Previous calculations on semiconductors with indirect band gaps found that the best thermoelectrics had gaps equal to ${\mathit{nk}}_{\mathit{B}}$T, where n=6-10 and T is the operating temperature of the thermoe…
The addition of suitable dopants to ${\mathrm{ZrO}}_{2}$ can induce dramatic phase stabilization, and this dopant-induced phase stabilization is the basis of transformation toughening of zirconia-based structural ceramics. We have determined the electronic structure of three phases of ${\mathrm{ZrO}}_{2}$, cubic, tetr…
Based upon the similarities in properties between carbon- and BN-based (BN=boron nitride) materials, we propose that BN-based nanotubes can be stable and study their electronic structure. A simple Slater-Koster tight-binding scheme has been applied. All the BN nanotubes are found to be semiconducting materials. The ba…
Abstract Glycidol has been introduced into isocyanate‐terminated polyurethane to form glycidyl‐terminated polyurethane resin. A series of glycidyl‐terminated polyurethanes, based on PTMEG, PPG, and polyester soft segments, having different molecular weights were synthesized and their adhesion properties on aluminum we…