Open AccessAnharmonic effective pair potentials in CaTiO 3 , SrTiO 3 and CaGeO 3 perovskite
Author(s) -
Yoshiasa Akira,
Nakajima Kenji,
Murai Keiichiro,
Okube Maki
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049500020689
Subject(s) - perovskite (structure) , anharmonicity , condensed matter physics , materials science , physics , atomic physics , chemistry , crystallography
The temperature dependence of EXAFS Debye–Waller factors in CaTiO 3 , SrTiO 3 and CaGeO 3 perovskite was investigated with the cumulant expansion method. The CaGeO 3 perovskite as an analogue of the Earth's lower‐mantle mineral was synthesized in a cubic anvil type apparatus under 10 GPa 1250 K. The Ca, Ti and Ge K‐edge EXAFS spectra were measured in transmission mode at temperature up to 1100 K. The effective pair potentials, V(u) = αu 2 /2 + βu3/3!, were evaluated and the Grüneisen parameter were calculated. The potential coefficients α and β for Ti—O bond in CaTiO 3 are 6.9 eV Å −2 and −38 eV Å −3 , respectively. Those for Ge—O bond in CaGeO 3 are 9.8 eV Å −2 and −36 eV Å −3 , respectively.