The temperature dependence of EXAFS Debye-Waller factors in CaTiO3, SrTiO3 and CaGeO3 perovskite was investigated with the cumulant expansion method. The CaGeO3 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)= α u2/2+βu3/3!, were evaluated and the Grüneisen parameter were calculated. The potential coefficients α and β for Ti-O bond in CaTiO3 are 6.9 eVÅ-2 and -38 eVÅ-3, respectively. Those for Ge-O bond in CaGeO3 are 9.8 eVÅ-2 and -36 eVÅ-3, respectively.
- Anharmonic effective pair potential
- EXAFS Debye-Waller factor
- Metastable CaGeO
ASJC Scopus subject areas
- Nuclear and High Energy Physics