Structural Evolution, Strain and Elasticity of Perovskites at High Pressures and Temperatures
Analysis of pressure-temperature dependent monochromatic X-ray powder diffraction data yield the bulk modulus [KT = 180.2(28) GPa] and thermal expansion coefficients [{alpha}0 = 2.841(34) x 10-5 K-1; {alpha}1 = 3.37(48) x 10-9 K-2] of CaIrO3, the structure model for post-perovskite MgSiO3. CaIrO3 is orthorhombic (Cmcm, space group 63, Z = 4) with best-fit unit-cell parameters, a = 3.14147(5) Angstroms, b = 9.87515(19), c = 7.29711(11), and V = 226.3754(78) Angstroms 3 at 1 bar and 300 K. The c-axis of CaIrO3 has a small compressibility and a large thermal expansion when compared to the other principal axes. Rietveld structure refinement reveals changes in CaIrO3 as a function of temperature in terms of IrO6 octahedra distortion. Dissociation of CaIrO3 at high temperature has possible implications for the post-perovskite MgSiO3 structure, Earth's lower mantle, and D' layer.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 960062
- Report Number(s):
- BNL-83048-2009-JA; TRN: US201016%%1206
- Journal Information:
- Journal of Mineral and Petrological Sciences, Vol. 101
- Country of Publication:
- United States
- Language:
- English
Similar Records
The local post-perovskite structure and its temperature dependence : atom-pair distances in CalrO{sub 3} revealed through analysis of the total x-ray scattering at high temperatures.
High temperature-induced phase transitions in Sr{sub 2}GdRuO{sub 6} complex perovskite