Thermal Equation of State of CaIrO3 Post-perovskite
The pressure-volume-temperature (P-V-T) relation of CaIrO{sub 3} 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 K{sub T0} at ambient pressure and temperature is 168.3 {+-} 7.1 GPa with a pressure derivative K{sub 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-Grueneisen-Debye formalism. The refined thermoelastic parameters for CaIrO{sub 3} ppv are: temperature derivative of bulk modulus ({partial_derivative}K{sub T}/{partial_derivative}T){sub P} = -0.038 {+-} 0.011 GPa K{sup -1}, {alpha}K{sub T} = 0.0039 {+-} 0.0001 GPa K{sup -1}, ({partial_derivative}K{sub T}/{partial_derivative}T){sub V} = -0.012 {+-} 0.002 GPa K{sup -1}, and ({partial_derivative}{sup 2}P/{partial_derivative}T{sup 2}){sub V} = 1.9 {+-} 0.3 x 10{sup -6} GPa{sup 2} K{sup -2}. Using the Mie-Grueneisen-Debye formalism, we obtain Grueneisen parameter {gamma}{sub 0} = 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 K{sub T0} = 5406.0/V(molar) + 5.9 GPa.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1042053
- Report Number(s):
- BNL-97731-2012-JA; PCMIDU; TRN: US201212%%464
- Journal Information:
- Physics and Chemistry of Minerals, Vol. 38, Issue 5; ISSN 0342-1791
- Country of Publication:
- United States
- Language:
- English
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