Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Liu, W. Articles by Li, B.

Thermal equation of state of CaGeO₃ perovskite

¹ Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794, U.S.A.
² Department of Earth Sciences, National Cheng-Kung University, Tainan 70101, Taiwan

Correspondence: ^* E-mail: weiliu3{at}notes.cc.sunysb.edu

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 x 10^–5/K, and b = 3.282 ± 0.735 x 10^–8/K² for the thermal expansion expressed by a + bT. The thermal pressure approach yields K_T = 4.04 ± 0.37 x 10^–3 GPa/K and (²P/T²)_V = 6.17 ± 1.28 x 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.

Key Words: CaGeO₃ perovskite • equation of state • thermal pressure • high pressure and high temperature • X-ray diffraction