The pressure-volume-temperature (P-V-T) relation of CaIrO3 post-perovskite (ppv) was measured at pressures and temperatures up to 8.6 GPa and 1,273 K, respectively, with energy-dispersive synchrotron X-ray diffraction using a DIA-type, cubic-anvil apparatus (SAM85). Unit-cell dimensions were derived from the Le Bail full profile refinement technique, and the results were fitted using the third-order Birth-Murnaghan equation of state. The derived bulk modulus KT0 at ambient pressure and temperature is 168.3 ± 7.1 GPa with a pressure derivative K′T0 = 5.4 ± 0.7. All of the high temperature data, combined with previous experimental data, are fitted using the high-temperature Birch-Murnaghan equation of state, the thermal pressure approach, and the Mie-Grüneisen-Debye formalism. The refined thermoelastic parameters for CaIrO3 ppv are: temperature derivative of bulk modulus (∂KT/∂T)P = -0.038 ± 0.011 GPa K-1, αKT = 0.0039 ± 0.0001 GPa K-1,(∂KT/∂T)V = -0.012 ± 0.002 GPa K-1, and (∂2P/∂T2)V = 1.9 ± 0.3 × 10-6 GPa2 K-2. Using the Mie-Grüneisen-Debye formalism, we obtain Grüneisen parameter γ0 = 0.92 ± 0.01 and its volume dependence q = 3.4 ± 0.6. The systematic variation of bulk moduli for several oxide post-perovskites can be described approximately by the relationship KT0 = 5406.0/V(molar) + 5.9 GPa.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Geochemistry and Petrology
- CaIrO post-perovskite
- High pressure and high temperature
- Thermal equation of state