Pressure-volume-temperature data have been obtained for CaGeO 3 perovskite up to 9.6 GPa and 1100 K using a cubic anvil, DIA-type high-pressure apparatus in conjunction with synchrotron X-ray diffraction. The data were analyzed using Birch-Murnaghan equation of state and thermal pressure approach with the bulk modulus at ambient pressure, K TO , and its pressure derivative, K TO , constrained by previous measurements. A fit of the unit-cell volume data to the high-temperature Birch-Murnaghan (HTBM) equation of state gives (∂K T /∂T) P = -0.025 ± 0.015 GPa/K, a = 1.047 ± 0.356 × 10 -5 /K, and b = 3.282 ± 0.735 × 10 -8 /K 2 for the thermal expansion α expressed by a + bT. The thermal pressure approach yields αK T = 4.04 ± 0.37 × 10 -3 GPa/K and (∂P/∂T 2 ) v = 6.17 ± 1.28 × 10 -6 GPa/K 2 . The energy dispersive X-ray diffraction data reveal no indication of a structural phase transition over the P-T range of the cur-rent experiment. A systematic relationship, K SO = 6720/V(molar) - 13.07 GPa, has been established based on these isostructural analogues, which predicts K SO = 261(15) for MgSiO 3 perovskite and 225(8) for CaSIO 3 perovskite, respectively.
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology