Elasticity and equation of state of MgSiO3 perovskite

The elastic constants and equation of state of MgSiO3 perovskite and MgO are calculated as functions of pressure and temperature using the potential induced breathing (PIB) model, which is an ab initio model in the sense that no experimental data are used. Excellent agreement with experiment is found for the equation of state of perovskite. The calculated thermal expansivity is lower than determined experimentally. PIB provides pressure derivatives of elastic constants that are probably more accurate than experimental results, so that PIB pressure derivatives may be used with experimental elastic moduli when these become available for MgSiO3 perovskite. A fourth-order finite strain equation is required to fit the elastic moduli, since the shear modulus has only a small pressure dependence at high pressures. The calculated elastic properties are used to discuss the composition of the lower mantle. The results are consistent with a lower mantle composition enriched in Fe.

[1]  Earl K. Graham,et al.  The pressure and temperature dependence of the elastic properties of polycrystal magnesiowustite , 1982 .

[2]  Ronald E. Cohen,et al.  Theoretical studies of charge relaxation effects on the statics and dynamics of oxides , 1987 .

[3]  Raymond Jeanloz,et al.  Phase transitions and mantle discontinuities , 1983 .

[4]  M. Mehl,et al.  Phase transitions and elasticity in zirconia , 1988 .

[5]  Raymond Jeanloz,et al.  Thermal expansion of silicate perovskite and stratification of the Earth's mantle , 1986, Nature.

[6]  Ho-kwang Mao,et al.  Structure and crystal chemistry of perovskite-type MgSiO3 , 1978 .

[7]  J. Hardy,et al.  Ab Initio Calculations of the Effect of Non-Rigid Ions on the Statics and Dynamics of Oxides , 1985 .

[8]  R. Jeanloz,et al.  Synthesis and Equation of State of (Mg,Fe) SiO3 Perovskite to Over 100 Gigapascals , 1987, Science.

[9]  M. Born,et al.  Dynamical Theory of Crystal Lattices , 1954 .

[10]  Boyer,et al.  Potential-induced breathing model for the elastic moduli and high-pressure behavior of the cubic alkaline-earth oxides. , 1986, Physical review. B, Condensed matter.

[11]  Adam M. Dziewonski,et al.  Homogeneity and Constitution of the Earth's Lower Mantle and Outer Core , 1975 .

[12]  Roy G. Gordon,et al.  Theoretical study of the structure, lattice dynamics, and equations of state of perovskite-type MgSiO3 and CaSiO3 , 1987 .

[13]  W. Pickett,et al.  Applications of ionic models to the high-temperature superconductor La2CuO4 , 1988 .

[14]  Boyer,et al.  Beyond the rigid-ion approximation with spherically symmetric ions. , 1985, Physical review letters.

[15]  D. L. Anderson,et al.  Preliminary reference earth model , 1981 .

[16]  M. S. T. Bukowinski,et al.  Ab initio structural and thermoelastic properties of orthorhombic MgSiO3 perovskite , 1985 .

[17]  Boyer,et al.  Lattice dynamics of the potential-induced breathing model: Phonon dispersion in the alkaline-earth oxides. , 1987, Physical review. B, Condensed matter.

[18]  Takeo Matsumoto,et al.  Computational model of the structural and elastic properties of the ilmenite and perovskite phases of MgSiO3 , 1987 .

[19]  H. Mao,et al.  Transmission electron diffraction and microscopy of synthetic high pressure MgSiO3 phase with perovskite structure , 1980 .

[20]  Ronald E. Cohen,et al.  Calculation of elasticity and high pressure instabilities in corundum and stishovite with the Potential Induced Breathing Model , 1987 .

[21]  F. Birch,et al.  Finite strain isotherm and velocities for single‐crystal and polycrystalline NaCl at high pressures and 300°K , 1978 .

[22]  A. V. Vitjazev.  Heat generation and heat-mass transfer in the early evolution of the Earth , 1980 .

[23]  H. Mao,et al.  Hydrostatic Compression of Perovskite-Type MgSiO3 , 1982 .

[24]  Alfred Edward Ringwood,et al.  Origin of the Earth and Moon , 1979 .

[25]  Z. Chang,et al.  Pressure dependence of the elastic constants of single-crystalline magnesium oxide , 1969 .

[26]  O. L. Anderson,et al.  Anharmonicity of three minerals at high temperature: Forsterite, fayalite, and periclase , 1983 .

[27]  Raymond Jeanloz,et al.  Lattice dynamics and structural distortions of CaSiO3 and MgSiO3 perovskites , 1985 .