Equation of state of MgSiO3 with the perovskite structure based on experimental measurement

We studied MgSiO3 with the perovskite structure heated to temperatures up to 1500 K at pressures between 36 and 110 GPa with in-situ X-ray diffraction. The new pressure-volume-temperature (P-V-T) data were combined with literature data. to provide thermal expansivity a and compressibility beta against T (in K): alpha(r) = 2.71 x 10(-5) + 1.80 x 10(-9) T - 1.48 T-2 (Model 1) or alpha(r) = 2.13 x 10(-5) + 7.57 x 10(-9) T - 1.02 T-2 (Model 2), and beta(1) = 3.735 x 10(-7) + 3.27 x 10(-11) T + 6.60 x 10(-15) T-2. Model 1 yields physical properties of perovskite that confirm Anderson's (1998) Debye approach; the model is valid for extrapolation to 3000 K or more. The parameters at 300 K are: alpha = 1.1 x 10?, K-o (bulk modulus) = 261 GPa, K-o' = 4 and (partial derivative K/partial derivative T)(P) = -0.027. Thermal expansivity from this model does not fit the data of Funamori et al. (1996) at high temperature for P = 25 GPa. Model 2 uses an equation for a based on the data of Funamori et al. (1996), fits the available experimental data closely, and maintains conformity with Anderson's Debye approach. Heat capacity, C-P, data for perovskite is given by either: C-P = 110.8 +/- 8.031 x 10(-3) T - 1.302 x 10(-7) T-2 - 1.647 x 10(7) T-2 + 2.755 x 10(9) T-3 + 267.5 T-0.5 + 9287 T-1 (Model 1) or C-P = 121.33 + 2.77 x 10(-3) T - 2.585 x 10(6) T-2 - 1.710 x 10(7) T + 2.792 x 10(9) T-3 - 169 T-0.5 + 15782 T-1 (Model 2).