Abstract Silicon is of great economic importance for the semiconductor industry as well academic interest because its high-pressure phase transformations. These transformations also occur during indentation silicon. To further investigate these transformations, a modified method using continuous stiffness measurement (CSM) unloading presented in this work. The use CSM signal allows directly cal...

Under high pressure, the phase transition mechanism and mechanical property of material are supposed to be largely associated with the transformation induced elastic strain. However, the experimental evidences for such strain are scanty. The elastic and plastic properties of ZnO, a leading material for applications in chemical sensor, catalyst, and optical thin coatings, were determined using i...

Raman spectroscopy, synchrotron angle-dispersive X-ray diffraction (ADXRD), first-principles calculations, and electrical resistivity measurements were carried out under high pressure to investigate the structural stability and electrical transport properties of metavanadate MgV2O6. The results have revealed the coordination change of vanadium ions (from 5+1 to 6) at around 4 GPa. In addition, ...

Superconductivity in the recently proposed ground-state structures of atomic metallic hydrogen is calculated over the pressure range 500 GPa to 3.5 TPa. Near molecular dissociation, the electron-phonon coupling λ and renormalized Coulomb repulsion are similar to the molecular phase. A nearly continuous increase in the critical temperature Tc with pressure is thus predicted in this range, to ∼35...

1. Introduction High-pressure minerals, produced by shock metamorphism, are common in and around melt veins in highly shocked chondrites [1-8]. These minerals either crystallized from silicate melt in the shock-vein or formed by solid-state transformed from host-rock fragments entrained in the melt or along shock-vein margins [3]. The study of these high pressure minerals can give us a better u...

Structural transformation in gallium arsenide nanocrystals under pressure is studied using molecular-dynamics simulations on parallel computers. It is found that the transformation from fourfold to sixfold coordination is nucleated on the nanocrystal surface and proceeds inwards with increasing pressure. Inequivalent nucleation of the high-pressure phase at different sites leads to inhomogeneou...

We report on the pressure-induced phase transition in a model of paracrystalline silicon ~amorphous silicon with a crystalline grain! using an ab initio constant pressure simulation technique. The paracrystalline model transforms into a high-density amorphous phase at 16 GPa with a discontinuous volume change of ;24%. The transformation of the crystalline grain begins at the boundary and procee...

We predict by first principles a phase transition in alumina at approximately 3.7 Mbar and room temperature from the CaIrO(3)-type polymorph to another with the U(2)S(3)-type structure. Because alumina is used as window material in shock-wave experiments, this transformation should be important for the analysis of shock data in this pressure range. Comparison of our results on all high-pressure...