High-pressure polymorph of CoPO: phase transition to an olivine-related structure.

The monoclinic polymorph of CoPO (space group 2/), isomorphic to farringtonite (MgPO) type orthophosphates, was studied up to 21 GPa using synchrotron powder X-ray diffraction and density-functional theory simulations to investigate the influence of pressure in the crystal structure. This study revealed a pressure induced structural phase transition for monoclinic cobalt phosphate, CoPO, and the details of crystal structure of the new high-pressure polymorph were delineated. The evolution of XRD pattern with pressure indicate that the onset of a phase transition occurs around 2.

PbVO under compression: near zero-linear compressibility and pressure-induced change in vanadium coordination.

This study presents evidence that lead metavanadate, PbVO, is a material with zero-linear compressibility, which maintains its crystal size in one crystallographic direction even under external pressures of up to 20 GPa. The orthorhombic polymorph of PbVO (space group ) was studied up to 20 GPa using synchrotron powder X-ray diffraction, Raman spectroscopy, and density-functional theory simulations to investigate its structural and vibrational evolution under compression. Up to this pressure we find no evidence of any structural phase transitions by any diagnostic technique, however, a progressive transformation of the coordination polyhedron of vanadium atoms is revealed which results in the zero-linear compressibility.

Electronic, Vibrational, and Structural Properties of the Natural Mineral Ferberite (FeWO): A High-Pressure Study.

This paper reports an experimental high-pressure study of natural mineral ferberite (FeWO) up to 20 GPa using diamond-anvil cells. First-principles calculations have been used to support and complement the results of the experimental techniques. X-ray diffraction patterns show that FeWO crystallizes in the wolframite structure at ambient pressure and is stable over a wide pressure range, as is the case for other wolframite AWO (A = Mg, Mn, Co, Ni, Zn, or Cd) compounds.

Equations of State and Crystal Structures of KCaPO, KSrPO, and KCe(PO) under High Pressure: Discovery of a New Polymorph of KCaPO.

We have studied by means of angle-dispersive powder synchrotron X-ray diffraction the structural behavior of KCaPO, SrKPO, and KCe(PO) under high pressure up to 26, 25, and 22 GPa, respectively. For KCaPO, we have also accurately determined the crystal structure under ambient conditions, which differs from the structure previously reported. Arguments supporting our structural determination will be discussed.

High-Pressure X-ray Diffraction Study of Orthorhombic CaZrTiO.

The orthorhombic polymorph of CaZrTiO (space group ) has been studied by powder X-ray diffraction under high pressures up to 30 GPa using synchrotron radiation. We have found evidence of a structural phase transition at 12-13 GPa. The phase transition causes an enhancement of the crystal symmetry.

Pressure-induced phase transitions and electronic properties of CdVO.

We report a density-functional theory study of the structural and electronic properties of CdVO under high-pressure conditions. The calculations have been performed by using first-principles calculations with the CRYSTAL program. The occurrence of two structural phase transitions, at 0.

Density-functional study of pressure-induced phase transitions and electronic properties of ZnVO.

We report a study of the high-pressure behavior of the structural and electronic properties of ZnVO by means of first-principle calculations using the CRYSTAL code. Three different approaches have been used, finding that the Becke-Lee-Yang-Parr functional is the one that best describes ZnVO. The reported calculations contribute to the understanding of previous published experiments.

Author Correction: Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell.

The high-pressure and high-temperature structural and chemical stability of ruthenium has been investigated via synchrotron X-ray diffraction using a resistively heated diamond anvil cell. In the present experiment, ruthenium remains stable in the hcp phase up to 150 GPa and 960 K. The thermal equation of state has been determined based upon the data collected following four different isotherms.