Comparative crystal chemistry of silicates beyond 20 GPa

Crystal chemistry of silica - rich barium silicates II : Electron microscopy of barium silicates containing multiple chains

The phases containing multiple chains in the series Ba",+1[Si2mOsm+d those with triple (m = 3), quadruple (m = 4) and quintuple (m = 5) tetrahedral chains were investigated by high resolution transmission electron microscopy. The resulting images could be correlated with the structures. Variations of the chain multiplicity (m) within single crystals were observed as well as faults in the packin...

Comparative Crystal Chemistry of Dense Oxide Minerals

Oxygen is the most abundant element in the Earth, constituting about 43 percent by weight of the crust and mantle. While most of this mass is incorporated into silicates, the next most abundant mineral group in the planet is the oxides. The oxide minerals are generally considered to be those oxygen-based minerals that do not contain a distinct polyanionic species such as OH, CO3, SO4 PO4, SiO4,...

Comparative Crystal Chemistry of Orthosilicate Minerals

Crystal chemistry of hydrous forsterite and its vibrational properties up to 41 GPa

The crystal structure of hydrous pure magnesium forsterite (Mg2SiO4) containing 8900 ppmw H2O, synthesized at 12 GPa and 1250 °C, has been refined. The major hydration mechanism appears to be M1 cation vacancy with protonation of the O1-O2 octahedral edge of M1. Raman spectra up to 41 GPa show strong coupling between the two Ag modes (824.4 and 856.2 cm–1). Mode Grüneisen parameters γi related ...

Single-crystal elasticity and sound velocities of (Mg0.94Fe0.06)O ferropericlase to 20 GPa

[1] The single-crystal elastic properties of high-spin (Mg0.94Fe0.06)O ferropericlase were measured by Brillouin spectroscopy on a sample compressed to 20 GPa with diamond anvil cells using methanol-ethanol-water as a pressure-transmitting medium. At room pressure, the adiabatic bulk (K0S) and shear (m0S) moduli are K0S = 163 ± 3 GPa and m0S = 121 ± 2 GPa, in excellent agreement with ultrasonic...