Materials Literature
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Using the non-empirical Variational Induced Breathing (VIB) model, the thermal properties of periclase (MgO) under high pressures and temperatures are investigated using molecular dynamics, which includes all anharmonic effects. Equations of state for temperatures up to 3000K and pressures up to 310 GPa were calculate…
Adaptive coordinates are shown to be effective in allowing the accurate calculation of structures and interatomic forces for solids containing first-row atoms using relatively small orthonormal sets of basis functions. Several polymorphs of ${\mathrm{SiO}}_{2}$ are studied as illustrative test cases.
Local-density-functional pseudopotential theory is used to investigate native defects in diamond, their structure, electronic, vibrational, and diffusive properties. We find the only truly stable structure for an interstitial atom to be the 〈100〉 split interstitial defect. This conclusion holds in the neutral, -1, +1,…
We have investigated the adsorption and thermal conversion of molecular oxygen (O2) states on the TiO2(110) surface by making use of the distinct photodesorption behavior of each adsorption state. Oxygen chemisorbs at the oxygen vacancy defect sites on the annealed TiO2(110) surface at 105 K to a saturation coverage o…
High-quality, size-selected, nano-size (2--15 nm\ifmmode\pm\else\textpm\fi{}10%) clusters of ${\mathrm{MoS}}_{2}$ have been successfully grown inside inverse micellar cages and their optical properties have been studied. These clusters exhibit (1) large blueshifts in the optical-absorption features with decreasing clu…
Potassium fluoroboratoberyllate KBe2BO3F2 (KBBF) has been revealed theoretically and experimentally as a novel ultraviolet nonlinear optical crystal, but it is found to be very difficult to grow in a large size, because of the weak binding interaction between the (Be2BO3)∞ units, which leads to an apparent layer habit…
We report low-temperature absorption, time-integrated photoluminescence, and resonant-Raman-scattering spectra near the fundamental band gap of ${\mathrm{TiO}}_{2}$ single crystals. The photoluminescence spectrum comprises a first peak at \ensuremath{\Elzxh}\ensuremath{\omega}=3.031 eV, followed by several peaks at lo…
Structural transformations in CdSe nanocrystals are studied using high pressure x-ray diffraction and high pressure optical absorption at room temperature. The nanocrystals undergo a wurtzite to rock salt transition analogous to that observed in bulk CdSe. Both the thermodynamics and the kinetics of the transformation…
The quasiparticle band structure of bulk hexagonal boron nitride is studied within the GW approximation for the self-energy operator. The influence of the interlayer distance on the band structure is investigated both within the local density approximation and the quasiparticle approach, and the importance of an inter…
Abstract The liquefied wood resins obtained by liquefying wood in the presence of phenol using phosphoric acid as a catalyst were applied to prepare the moldings by using hexamine as a hardener. The effects of the molding conditions and the moldings' compositions on flexural properties and water‐sorption kinetics of t…
We propose two different macroscopic dynamics to describe the decay of metastable phases in many-particle systems with local interactions. These dynamics depend on the macroscopic order parameter $m$ through the restricted free energy $F(m)$ and are designed to give the correct equilibrium distribution for $m$. The co…
Erbium surface segregation is observed during growth of Er-doped Si by molecular beam epitaxy on Si(100) at 600 °C. Once a critical Er surface areal density of 2×1014 Er/cm2 is reached, enhanced Er trapping is observed, possibly due to the formation of silicide precipitates. Er segregation on Si(100) is fully avoided…
Silicon samples were implanted with 20 keV He at various temperatures. The damage and the size of the He bubbles created during the implantation were measured with Raman spectroscopy and transmission electron microscopy. Room temperature implantation with 2.5×1017 He atoms/ cm2 produced an amorphized layer with a high…
The magnetic properties of icosahedral Mg 42 RE 8 Zn 50 (RE identical to Gd, Tb, Dy, Ho or Er) quasi-crystals have been investigated. These quasi-crystalline phases have a face-centred icosahedral lattice with a highly ordered Frank-Rasper-type structure as identified by electron diffraction and X-ray diffraction. The…
We report on the structure and composition of codeposited thin Ag and Cu films on a Ru(0001) substrate. All three metals are immiscible in their bulk forms, however, monolayer films of Ag and Cu are observed to alloy on Ru(0001). In the dilute Cu case, preferential formation of the alloy is found. With increasing Cu c…
The magnetoresistance of epitaxial Nd0.7Sr0.3MnOδ thin films has been studied. A giant magnetoresistance, with more than 4 orders of magnitude change in resistance (−ΔR/RH≳106%), was obtained at ∼60 K and a magnetic field of 8 T. This giant magnetoresistance (GMR) ratio is about one order of magnitude larger than the…
${}^{30}\mathrm{Si}$ diffusion was measured in quartz along c axis in the $\ensuremath{\beta}$-phase field, at $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1400$-- $1600\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ by Rutherford backscattering spectrometry and the ${}^{30}\mathrm{Si}(p,\ensuremath{\gamma})^{3…
The role of externally-controlled chemical reactions in the selection of patterns in phase-separating mixtures is presented. Linearized theory and computer simulation show that the initial long-wavelength instability characteristic of spinodal decomposition is suppressed by chemical reactions, which restrict domain gr…
Electroluminescence is obtained from nearly monodisperse CdSe nanocrystallites (quantum dots) incorporated into thin films (1000 Å) of polyvinylcarbazole (PVK) and an oxadiazole derivative (t-Bu-PBD) and sandwiched between ITO and Al electrodes. The electroluminescence and photoluminescence spectra (bandwidths ≤40 nm)…
A numerical study is presented of the motion of two-dimensional, doubly periodic, dilute and concentrated emulsions of liquid drops with constant surface tension, subject to a simple shear flow. The numerical method is based on a boundary integral formulation that employs a Green's function for doubly periodic Stokes…