HR: 0800h
AN: V41C-1400    [Abstracts]
TI: Crystal chemistry of NaMgF3 perovskite at high pressure and temperature
AU: * Chen, J
EM: Jiuhua.Chen@sunysb.edu
AF: SUNY at Stony Brook, ESS Bldg, Stony Brook, NY 11794 United States
AU: Liu, H
AF: Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 United States
AU: Martin, C D
AF: SUNY at Stony Brook, ESS Bldg, Stony Brook, NY 11794 United States
AU: Parise, J
AF: SUNY at Stony Brook, ESS Bldg, Stony Brook, NY 11794 United States
AU: Weidner, D
AF: SUNY at Stony Brook, ESS Bldg, Stony Brook, NY 11794 United States
AB: The crystal structure of NaMgF3 perovskite (neighborite) is studied at 4GPa and temperatures up to $1000\deg$C using Rietveld structure refinement method and In situ synchrotron X-ray powder diffraction collected using monochromatic radiation. The orthorhombic (Pbnm) to cubic (Pm3m) transition is observed when temperature increases from $900\deg$C to $1000\deg$C. Structure refinements show that the ratio of polyhedral volumes of the A- and B-sites (VA/VB) of the orthorhombic phase increases with temperature, approaching the ideal value (5) for the cubic structure. However, this ratio becomes smaller at 4GPa compared to the result from previous studies at the same temperature but ambient pressure, indicating that pressure makes it more difficult to transform from the orthorhombic phase to the cubic phase in this kind of perovskite.
DE: 3600 MINERALOGY AND PETROLOGY (replaces
DE: 3620 Crystal chemistry
DE: 3630 Experimental mineralogy and petrology
DE: 3900 MINERAL PHYSICS
DE: 3924 High-pressure behavior
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting