Pressure- and temperature-dependent Raman spectra of CaFeO oxygen defect perovskite.

The Raman spectra of CaFeO were investigated up to 21.8 GPa at room temperature and up to 1073 K at ambient pressure, respectively. A phase transition begins around 13.

Raman and X-ray diffraction study of pressure-induced phase transition in synthetic MgTiO.

Synthetic MgTiO qandilite was investigated to 50 and 40.4 GPa at room temperature using Raman spectroscopy and X-ray diffraction, respectively. The Raman measurements showed that cubic MgTiO spinel transforms to a high pressure tetragonal (I4/amd, No.

A Spectral Comparison of Jarosites Using Techniques Relevant to the Robotic Exploration of Biosignatures on Mars.

The acidic sulfate-rich waters of the Meridiani Planum region were potentially a habitable environment for iron-oxidizing bacteria on ancient Mars. If life existed in this ancient martian environment, jarosite minerals precipitating in these waters may record evidence of this biological activity. Since the Meridiani jarosite is thermodynamically stable at the martian surface, any biosignatures preserved in the jarosites may be readily available for analysis in the current surface sediments during the ongoing robotic exploration of Mars.

Electronic structure of carbon dioxide under pressure and insights into the molecular-to-nonmolecular transition.

Knowledge of the high-pressure behavior of carbon dioxide (CO2), an important planetary material found in Venus, Earth, and Mars, is vital to the study of the evolution and dynamics of the planetary interiors as well as to the fundamental understanding of the C-O bonding and interaction between the molecules. Recent studies have revealed a number of crystalline polymorphs (CO2-I to -VII) and an amorphous phase under high pressure-temperature conditions. Nevertheless, the reported phase stability field and transition pressures at room temperature are poorly defined, especially for the amorphous phase.

Equation of state of the postperovskite phase synthesized from a natural (Mg,Fe)SiO3 orthopyroxene.

Using the laser-heated diamond anvil cell, we investigate the stability and equation of state of the postperovskite (ppv, CaIrO(3)-type) phase synthesized from a natural pyroxene composition with 9 mol.% FeSiO(3). Our measured pressure-volume data from 12-106 GPa for the ppv phase yield a bulk modulus of 219(5) GPa and a zero-pressure volume of 164.

Strength and elasticity of SiO2 across the stishovite-CaCl2-type structural phase boundary.

Radial x-ray diffraction experiments were conducted under nonhydrostatic compression on SiO2 to 60 GPa in a diamond anvil cell. This ratio of differential stress to shear modulus t/G is 0.019(3)-0.