Materials Literature
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We report on epitaxial growth of ZnO films on Si(111) substrates using an epitaxial GaN buffer layer. A rf magnetron sputtering process has been developed and utilized in growing epitaxial GaN buffers on Si, and then ZnO films on the GaN-buffered Si substrates. X-ray diffraction analysis shows that both the ZnO and Ga…
We have studied the Devonshire-Landau potential underlying the phase transition sequence of ${\mathrm{BaTiO}}_{3}$ using the first-principles effective Hamiltonian of Zhong, Vanderbilt, and Rabe [Phys. Rev. Lett. 73, 1861 (1994)], which has been very successful in reproducing the phase transitions and the dielectric a…
We present the results of a computer simulation of the atomic structures of large-angle symmetrical tilt grain boundaries (GBs) $Σ5$ (misorientation angles $\q{36.87}{^{\circ}}$ and $\q{53.13}{^{\circ}}$), $Σ13$ (misorientation angles $\q{22.62}{^{\circ}}$ and $\q{67.38}{^{\circ}}$). The critical strain level $ε_{crit…
We report that the ternary MgB2-xCx compounds adopt an isostructural AlB2-type hexagonal structure in a relatively small range of nominal carbon concentration, x<0.1. The lattice parameter a decreases almost linearly with increasing carbon content x, while the c parameter remains unchanged, indicating that carbon is e…
We have used x-ray diffraction with subnanosecond temporal resolution to measure the lattice parameters of orthogonal planes in shock compressed single crystals of silicon (Si) and copper (Cu). Despite uniaxial compression along the (400) direction of Si reducing the lattice spacing by nearly 11%, no observable change…
We investigate, through first-principles calculations, the stability and electronic structure of self-interstitials and vacancies in both hexagonal (graphite-like) and cubic boron nitride. We find that the self-interstitials ${\mathrm{N}}_{i}$ and ${\mathrm{B}}_{i}$ in hexagonal boron nitride $(h\ensuremath{-}\mathrm{…
We report the results of an experimental investigation on lasing mechanisms in optically pumped ZnO epilayers at room temperature. High-quality ZnO epilayers grown on sapphire by plasma-assisted molecular-beam epitaxy employing an MgO buffer were used. Free exciton emissions and their phonon replicas dominate the phot…
Monolithically integrated active cooling is an attractive way for thermal management and temperature stabilization of microelectronic and optoelectronic devices. SiGeC can be lattice matched to Si and is a promising material for integrated coolers. SiGeC/Si superlattice structures were grown on Si substrates by molecu…
The lattice thermal conductivity of Ge clathrates is investigated by evaluating the linear response theory heat current correlation functions using molecular dynamics. Clathrate crystals with and without guest atoms in their fullerane cages are studied. In comparison with that of diamond-phase Ge, the clathrate conduc…
We search for general patterns that explain the low field magnetoresistance at low temperatures in the system A(2-x)A'xFeMoO6. The observed linear dependence of the low field magnetoresistance with the saturation magnetization for the series is related to the antisite disorder at the Fe and Mo sites. This is explained…
A triode-type field emission display has been fabricated using carbon nanotube emitters. Purified single walled carbon nanotubes were selectively deposited onto a cathode electrode in a triode-type structure by an electrophoresis. Emission current was modulated with gate potentials of 100–300 V. A high brightness of 1…
We describe in situ synthesis and characterization of single-walled BN nanotubes terminated by fullerenelike structures using electron-cyclotron resonance nitrogen and electron beam boron sources onto polycrystalline tungsten substrates. Detailed comparisons of experimental high-resolution electron microscopy images a…
A transparent oxide semiconductor with delafossite structure, CuInO2, was found to exhibit both p-type and n-type conduction by doping of an appropriate impurity and tuning of proper film-deposition conditions. Thin films of Ca-doped or Sn-doped CuInO2 (optical band gap=∼3.9 eV) were prepared on α-Al2O3(001) single cr…
We report measurements on ropes of single-walled carbon nanotubes (SWNT) in low-resistance contact to nonsuperconducting (normal) metallic pads, at low voltage and at temperatures down to 70 mK. In one sample, we find a 2 orders of magnitude resistance drop below 0.55 K, which is destroyed by a magnetic field of the o…
We present new heat-conduction equations, named ballistic-diffusive equations, which are derived from the Boltzmann equation. We show that the new equations are a better approximation than the Fourier law and the Cattaneo equation for heat conduction at the scales when the device characteristic length, such as film th…
Abstract A model has been developed for calculating the rates of general corrosion of carbon steel and 13%Cr steel in aqueous systems containing carbon dioxide, hydrogen sulfide and other components. The model combines a comprehensive thermodynamic speciation module with electrochemical computations based on the mixed…
Abstract The corrosion of materials by organic acids is complicated by the virtually unlimited number of possible compounds. The corrosion of metals by organic acid is often confounded by trace impurities such as oxygen and metallic salts. This paper concentrates on corrosion by acetic, formic and propionic acids and…
Abstract Tantalum materials have been used in the Chemical Processing Industry (CPI) for over 60 years and continue to be important materials of construction. This paper will discuss tantalum and Ta-2.5W alloy applications that have evolved over the past century to current day applications. Traditional upper limits fo…
Abstract This article first of all summarizes recent changes in the understanding of hydrogen charging and hydrogen stress cracking (HSC) mechanisms : In a completely unexpected manner, hydrogen charging is found to coexist with significant degassing of the metal towards the corrosive medium. The surface reaction 2 Ha…
Abstract The paper describes the synthesis and evaluation of a series of environmentally friendly corrosion inhibitors. These products were designed especially to use in North Sea Oil fields and in other environmentally sensitive areas as green inhibitors of CO2 corrosion. More than thirty peptides, some with random a…