Compression behavior of GeO2(quartz): possible high-pressure polymorphism

Anomalous anisotropic compression behavior of superconducting CrAs under high pressure.

CrAs was observed to possess the bulk superconductivity under high-pressure conditions. To understand the superconducting mechanism and explore the correlation between the structure and superconductivity, the high-pressure structural evolution of CrAs was investigated using the angle-dispersive X-ray diffraction (XRD) method. The structure of CrAs remains stable up to 1.8 GPa, whereas the latti...

HIGH PRESSURE BEHAVIOR OF KCl: STRUCTURAL AND ELECTRONIC PROPERTIES

The high pressure behavior of the structural and electronic properties of KC1 is studied with use of the density functional pseudopotential method within local-density approximation. Atzero pressure, the rocksalt phase is found to be lower in energy than CsCl structure. However, we predict a phase transition into CsCI structure at a pressure of about 1.5 GPa. The calculated ground state pro...

High Pressure Polymorphism in Silica

Fundamental crystal chemistry and first-principles total-energy calculations are used to examine stable and metastable high-pressure silica structures. We find that a large class of energetically competitive phases can be generated from hcp arrays of oxygen with silicon occupying one-half of the octahedral sites. Calculations for specific structures provide an explanation for a number of recent...

High-Pressure Shock Compression of Condensed Matter

High pressure polymorphism of β-TaON.

The high pressure behavior of TaON was studied using a combination of Raman scattering, synchrotron X-ray diffraction, and X-ray absorption spectroscopy in diamond anvil cells to 70 GPa at ambient temperature. A Birch-Murnaghan equation of state fit for baddeleyite structured β-TaON indicates a high bulk modulus value Ko = 328 ± 4 GPa with K = 4.3. EXAFS analysis of the high pressure XAS data p...