We explored the B-C-O system at pressures in the range 0-50 GPa by ab initio variable-composition evolutionary simulations in the hope of discovering new stable superhard materials. A new tetragonal thermodynamically stable phase B4CO4, space group I4[combining macron], and two low-enthalpy metastable compounds (B6C2O5, B2CO2) have been discovered. Computed phonons and elastic constants show th...

A first-principles study of the vibrational modes of PbTiO3 in the ferroelectric tetragonal phase has been performed at all the main symmetry points of the Brillouin zone ~BZ!. The calculations use the local-density approximation and ultrasoft pseudopotentials with a plane-wave basis, and reproduce well the available experimental information on the modes at the G point, including the LO-TO spli...

The purpose of this study was to use a tape casting technique to develop an Al2O3 fiber-reinforced Al2O3-based ceramic material (Al2O3-fiber/Al2O3 composite) into a new type of dental ceramic. The Al2O3-based ceramic used a matrix consisting of 60 wt% Al2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of Al2O3-fiber/Al2O3 composite (in which uniaxially aligned Al2O3 fibers were infilt...

High-resolution electron microscopy was employed to characterize the interface structure of a cast Al-Mg-Si-Bi-Pb aluminium(6262)-based composite reinforced by alpha alumina particles with a trace of beta alumina in order to investigate the behaviour of alloying elements in cast composites. Except for a few primary Mg2Si particles, few reaction products were detected at the interface of Al/alph...

Ceria-terbia solid solution nanobelts were prepared by an electrochemical route and tested as catalysts of high activity for CO oxidation.

The water-vapor sorption processes in nanoporous MgO-Al2O3 ceramics are studied with positron annihilation lifetime (PAL) spectroscopy employing positron trapping and positronium (Ps)-decaying modes. It is demonstrated that the longest-lived components in the four-term reconstructed PAL spectra with characteristic lifetimes near 2 and 60-70 ns can be, respectively, attributed to ortho-positroni...

The non-sulfided Ni-PTA/Al2O3 catalyst was developed to produce green diesel from the hydroprocessing of Jatropha oil. The Ni-PTA/Al2O3 catalyst was prepared by one-pot synthesis of Ni/Al2O3 with the co-precipitation method and then impregnanting Ni/Al2O3 with PTA solution. The catalysts were characterized with BET, SEM-EDX, TEM, XRD, XPS, TGA and NH3-TPD. The Ni and W species of the Ni-PTA/Al2...

Nb-B-Al-O nanocomposite films with different power of Al2O3 were successfully deposited on the Si substrate via multi-target magnetron co-sputtering method. The influences of Al2O3's content on structure and properties of obtained nanocomposite films through controlling Al2O3's power were investigated. Increasing the power of Al2O3 can influence the bombarding energy and cause the momentum tran...

ALD high-κ dielectrics and TiN metal-gate were successfully incorporated in both Si and Si0.7Ge0.3 surface-channel pMOSFETs. The high-κ gate dielectrics used included Al2O3 /HfAlOx /Al2O3, Al2O3 /HfO2 /Al2O3 and Al2O3. The Si transistors with Al2O3 /HfAlOx /Al2O3 showed a sub-threshold slope of 75 mV/dec. and a density of interface states of 3×10 cmeV. No obvious degradation of the Si channel h...