A proposed equation of state of stishovite

The available shock-wave data for solid α quartz in the stishovite pressure regime are reduced to a 25°C isotherm and an adiabat, centered at standard conditions, using recent standard density, enthalpy, and coefficient of thermal expansion data. The calculated isothermal bulk modulus, 3 Mb, as determined from the Birch-Murnaghan equation, depends critically on the value of (dK/dP)T at zero pressure and to a yet unknown extent on the form of the equation of state. The high-temperature value of Gruneisen's ratio (0.8 to 0.9) along the a quartz (stishovite regime) Hugoniot was obtained from the pressure offsets of the fused quartz and porous quartz Hugoniot. The high value for γ obtained from thermochemical data at standard conditions (1.5±0.3) suggests that a marked decrease in the value of γ to 0.8 occurs with increasing temperature.

[1]  Don L. Anderson,et al.  Equations of State and Crystal Structures of High-Pressure Phases of Shocked Silicates and Oxides , 1969 .

[2]  Murli H. Manghnani,et al.  Elastic constants of single‐crystal rutile under pressures to 7.5 kilobars , 1969 .

[3]  Leon Thomsen,et al.  On the high-temperature equation of state of solids. , 1969 .

[4]  O. L. Anderson,et al.  Comments on the negative pressure dependence of the shear modulus found in some oxides , 1968 .

[5]  D. L. Anderson,et al.  Shock‐wave equations of state for rocks and minerals , 1968 .

[6]  O. J. Kleppa,et al.  Thermodynamics of polymorphic transformations in silica. Thermal properties from 5 to 1070° K and pressure-temperature stability fields for coesite and stishovite , 1967 .

[7]  S. P. Marsh,et al.  On the equation of state of stishovite , 1963 .

[8]  W. Brace,et al.  Some direct measurements of the surface energy of quartz and orthoclase , 1962 .

[9]  Jerry Wackerle,et al.  Shock‐Wave Compression of Quartz , 1962 .

[10]  W. Bassett,et al.  Isothermal compression of stishovite and coesite up to 85 kilobars at room temperature by X-ray diffraction , 1970 .

[11]  Gene Simmons,et al.  Pressure derivatives of the elastic properties of polycrystalline quartz and rutile. , 1969 .

[12]  A. E. Ringwood,et al.  High pressure transformation of alkali aluminosilicates and aluminogermanates , 1967 .

[13]  E. Lilley,et al.  STATIC PV CURVES OF CRACKED AND CONSOLIDATED EARTH MATERIALS TO 40 KILOBARS. , 1966 .

[14]  O. L. Anderson,et al.  2 - Determination and Some Uses of Isotropic Elastic Constants of Polycrystalline Aggregates Using Single-Crystal Data , 1965 .