P - V - T equation of state of stishovite to the mantle transition zone conditions

Placing constraints on phase equilibria and thermophysical properties in the system MgO–SiO2 by a thermodynamically consistent vibrational method

“…Our description is based on V-P-T data of the first three investigations. Nishihara et al (2005) determined the pressure in their experiments from the observed unit cell volume of gold and the equation of state for gold constructed by Anderson et al (1989). However, Fei et al (2004b) showed that existing pressure scales for gold, including that of Anderson et al (1989), show significant differences in pressure calculated from the measured unit cell volume of gold at a specific temperature.…”

“…They established the value 309.9(11) for the isothermal bulk modulus at ambient conditions. Nishihara et al (2005) show that published ambient isothermal bulk modulus data range between 291 and 311 GPa. Considering the uncertainty in the published values this calls for an independent technique to establish the bulk modulus, such as that employed by Li et al (1996).…”

“…Constraining the static lattice properties hinges on the problem that volume-pressure measurements by Ross Table 5 Representation of experimental longitudinal (V P ), bulk (V B ) and transverse (V S ) sound velocities Liu et al (1999) and Nishihara et al (2005) are not consistent with those of Andrault et al (2003) and Panero et al (2003). Fig.…”

Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

“…In the experiments without boron-epoxy gasket windows, however, diffraction from the pyrophyllite gaskets and MgO pressure medium obscured the sample diffraction peaks and it was not possible to reliably calculate pressure or differential stresses from the olivine samples. In all the experiments though unique diffraction peaks from corundum were identifiable and used to determine the pressure from the equation of state of Dubrovinsky et al 6 In the 946 kN experiment, which did not use boron-epoxy windows, diffraction peaks from stishovite were also distinct and the pressure was determined from the unit cell volumes using the equation of state of Nishihara et al 32 The temperatures used in calculating the pressures were those measured by the thermocouple even though the temperature in the corundum or sample is unlikely to be the same as that measured by the thermocouple. The external thermocouple measures significantly lower temperatures than those experienced by sample 14 and at high temperatures there are significant thermal gradients along the furnace axis.…”

Equation of state of Ca2AlSiO5.5 oxygen defect perovskite

“…The density profiles of some silicate minerals including clinopyroxene, stishovite, majoritic garnet, MgSiO 3 perovskite, cubic and tetrahedral CaSiO 3 perovskites are also calculated for comparison. The data sources used were as follows: Nishihara et al (2003) for clinopyroxene (Cpx) with ρ 0 = 3.26 g/cm 3 ; Wang et al (1998) for majoritic garnet (Gt) with ρ 0 = 3.71 g/cm 3 (Ono et al 2001);Nishihara et al (2005) for stishovite (St) with ρ 0 = 4.25 g/cm 3 (Ono et al 2002); Shim et al (2000) for cubic Ca-perovskite (C-CaPv) with ρ 0 = 4.23 g/cm 3 ; Ono et al (2004b) for tetragonal Ca-perovskite (T-CaPv) with ρ 0 = 4.25 g/cm 3 ; and Ono et al (2004a) for Mg-perovskite (Mg-Pv) with ρ 0 = 4.35 g/cm 3 (Guignot and Andrault 2004). Generally, the chemical composition of each phase changes with increasing pressure and temperature in natural systems (Irifune et al 1994;Ono 1998;Ono et al 2001).…”