• journal_title：American Mineralogist
• Contributor：Wei Liu ; Jennifer Kung ; Liping Wang ; Baosheng Li
• Publisher：Mineralogical Society of America
• Date：2008-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2008.2428
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：93
• issue：5-6
• firstpage：745
• section：Articles

Pressure-volume-temperature data have been obtained for CaGeO₃ 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_T0, and its pressure derivative, K′_T0, 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/K² 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 (∂²P/∂T²)_V = 6.17 ± 1.28 × 10⁻⁶ GPa/K². The energy dispersive X-ray diffraction data reveal no indication of a structural phase transition over the P-T range of the current experiment. A systematic relationship, K_S0 = 6720/V(molar) − 13.07 GPa, has been established based on these isostructural analogues, which predicts K_S0 = 261(15) for MgSiO₃ perovskite and 225(8) for CaSiO₃ perovskite, respectively.