Pressure-volume-temperature behavior of fayalite based on static compression measurements at 400� C

Abstract

Abstract. Twenty-one energy-dispersive X-ray diffraction spectra for fayalite at 400~ constitute the basis for an elevated-temperature static compression isotherm for this important silicate mineral. A Murnaghan regression of the resulting molar volumes yields 103.8 GPa and 7.1 for the 400 ~ C, room-pressure values of the isothermal bulk modulus (Ko) and its first pressure derivative (K;), respectively. When compared to the room-temperature static compression isotherm of Yagi et al. (1975), our 400 ~ C value for Ko yields -5.4

Thermodynamic mixing properties of olivine derived from lattice vibrations

“…2. Jacobs et al (2001) were not able to discriminate between the thermal expansivity of Suzuki et al (1981) and that measured by Smyth (1975) and Plymate and Stout (1990). Figure 5 shows that the vibrational analyses of model G and I both prefer the thermal expansivity data measured by Suzuki et al (1981) and are compatible with model A in the analysis of Jacobs et al (2001).…”

“…The dotted curve labeled with c el is calculated using model G including electronic Grüneisen parameters given in ''Effect of volume on electronic and magnetic properties of fayalite''. The straight short dashed line is the thermal expansivity established by Plymate and Stout (1990) and the long dashed one that by Smyth (1975). b Calculated volume at 1 bar pressure using model I.…”

“…Ultrasonic data at room conditions are from Akimoto (1972), diamond, Wang et al (1989), asterisk. Results from static compression: Plymate and Stout (1990), triangle, Takahashi (1970), cross, Yagi et al (1975), plus Burns (1985) e g 9,270 5 M2 Burns (1985) anharmonicity, a j = a j,0 (V/V 0 ) m , in which a j,0 represents the anharmonicity parameter of a specific mode j at 0 K. That results in the same unsuccessful effect on the heat capacity. Presently, we are not able to resolve the discrepancy between our calculations and the experimental data of Orr (1953).…”

“…Both analyses prefer the thermal expansivity of fayalite by Suzuki et al (1981) and not those by Smyth (1975) and Plymate and Stout (1990). The use of electronic Grüneisen parameters to incorporate the pressure dependence of a number of electronic energy transitions has no significant effect on thermodynamic properties except for volume and thermal expansivity above room temperature.…”

Pressure-volume-temperature behavior of ?-Fe2SiO4 (spinel) based on static compression measurements at 400� C

“…In an earlier paper (Plymate and Stout 1990) we reported on the compressibility of fayalite (FezSiO 4 olivine) at 400~ and pressures to 8.0 GPa as measured by in situ x-ray diffraction in a heated diamond anvil pressure cell. Those compressibility measurements were made at elevated temperature in order to minimize nonhydrostatic effects and to evaluate the temperature dependence of various elastic properties.…”