Corundum, a-Al2O3, is the thermodynamically stable phase of coarsely crystalline aluminum oxide, but syntheses of nanocrystalline Al2O3 usually result in g-Al2O3. Adsorption microcalorimetry, thermogravimetric analyses, and Brunauer-Emmett-Teller adsorption experiments, coupled with recently reported high-temperature solution calorimetry data, prove that g-Al2O3 has a lower surface energy than ...

We present state-of-the-art molecular dynamics (MD) simulations of high-density plasma-bombardment of carbon, mimicking plasma–wall interactions at the fusion reactor first wall. Bare and hydrogenated amorphous carbon surfaces with temperatures in the range of 300–800 K are bombarded by a distribution of neutral hydrogen molecules representing well-defined center-of-mass and rovibrational tempe...

Most gas-surface chemical reactions occur via reaction of adsorbed species to form a thermal-energy ( approximately kT) product; however, some instances exist where an energetic projectile directly reacts with an adsorbate in a single-collision event to form a hyperthermal product (with a kinetic energy of a few eV). Here we show for the first time that 30-300 eV F(+) bombardment of fluorinated...

In this letter we present first-principles calculations of the surface energies of rock-salt (B1), zinc-blende (B3) and wurtzite (B4) AlN allotropes. Of several low-index facets, the highest energies are obtained for monoatomic surfaces (i.e. of only either Al or N atoms): [Formula: see text] and [Formula: see text]. The difference between Al- and N-terminated surfaces in these cases is less th...

To gain insight into surface processes in plasma processing, basic ion beam experiments are performed on two representative polyatomic-ion species: hydrocarbon ions CHx 1 for deposition processes and fluorocarbon ions CFx 1 for etching processes (x51,2, . . . ). A single ion species is extracted from an inductive plasma via a mass filter and directed onto aluminum surfaces at energies ,150 eV. ...

The bond-energy bond-order (BEBO) model of chemisorption allows an estimate to be made of the interaction energy between a gaseous specie and a solid surface as a function of either bond length or bond order, i.e., the length or order of either the gas-surface bond being formed or the bond of the gaseous molecule being broken. The relationship between bond energy and either bond length or bond ...

This study tested the following hypotheses: (1) acid-cleaned and passivated unalloyed titanium implants have higher surface energies (which are considered desirable for bone implants) than ethanol-cleaned titanium; (2) higher temperatures of heat treatment of unalloyed titanium result in higher surface energies; and (3) these changes can be related to changes in surface composition and roughnes...

in this paper, the correlation between the surface rumpling and cracking phenomena with twinning mechanism during plastic deformation of hadfield steel has been investigated. the effect of stacking fault energy and the amount of strain are evaluated. the experimental samples with specific amounts of carbon, manganese and aluminum resulting in different stacking fault energies, were produced usi...

Benchmarking DFT surface energies with quantum Monte Carlo S. J. Binnie abc; E. Sola ad; D. Alfè d; M. J. Gillan abc a Materials Simulation Laboratory, University College London, London, UK b Department of Physics and Astronomy, University College London, London, UK c London Centre for Nanotechnology, University College London, London, UK d Department of Earth Sciences, University College Londo...