HR: 1330h
AN: V42A-0335    [PDF]
TI: Neighborite Under High Pressure: {\it In Situ} Angle Dispersive X-ray Diffraction Study Using Synchrotron Radiation
AU: * Liu, H
EM: Haozhe.Liu@sunysb.edu
AF: Mineral Physics Institute, State University of New York at Stony Brook, ESS Bldg. SUNY SB, Stony Brook, NY 11794-2100 United States
AU: * Liu, H
EM: Haozhe.Liu@sunysb.edu
AF: Geophysical Lab, Carnegie Institution of Washington, 5251 Broad Branch Rd., N.W, Washington, DC 20015 United States
AU: Chen, J
EM: Jiuhua.Chen@sunysb.edu
AF: Mineral Physics Institute, State University of New York at Stony Brook, ESS Bldg. SUNY SB, Stony Brook, NY 11794-2100 United States
AU: Weidner, D
EM: Donald.Weidner@sunysb.edu
AF: Mineral Physics Institute, State University of New York at Stony Brook, ESS Bldg. SUNY SB, Stony Brook, NY 11794-2100 United States
AU: Hu, J
AF: Geophysical Lab, Carnegie Institution of Washington, 5251 Broad Branch Rd., N.W, Washington, DC 20015 United States
AU: Meng, Y
AF: Geophysical Lab, Carnegie Institution of Washington, 5251 Broad Branch Rd., N.W, Washington, DC 20015 United States
AU: Mao, H
AF: Geophysical Lab, Carnegie Institution of Washington, 5251 Broad Branch Rd., N.W, Washington, DC 20015 United States
AB: The neighborite (NaMgF$_{3}$) is an ideal analogue model for silicate perovskite (MgSiO$_{3}$) due to the similarities between their crystal and electronic structures. The advantage of the analogue study is that the weaker bonding feature of neighborite grants us the opportunity to simulate behavior of silicate perovskite at lower mantlei. e.high pressure and high temperature condition, at relatively lower P-T conditions. The previous high pressure studies for neighborite were reported by Zhao et al [1, 2]. Energy dispersive x-ray diffraction data were achieved within 10GPa and 1000$^{o}$C, while angle dispersive x-ray diffraction data were obtained only at 4.9GPa and room temperature.More information of atomic position change is required to reveal the role of MgF$_{6}$ octahedral framework tilting during its phase transition process responding to heating andcompressing. Thus the high-resolution monochromatic x-ray powder diffraction studies on NaMgF$_{3}$ perovskite at high pressure were carried out using diamond anvil cell at X17C of National Synchrotron Light Source (Brookhaven) and HPCAT of Advance Photon Source (Argonne). The orthorhombic structure keeps stable under pressure up to 30 GPa, and the crystal structure is refined using Rietveld method. The result indicates that tilting angle of the MgF$_{6}$ octahedral framework increases continually while the octahedral Mg-F bond length decreases slightly with increasing pressure.Difference between the tilting angles derived from macro-structure (lattice parameters) and from micro-structure (atomic positions), as well as the trend of change in the tilting angle with temperature and pressureare discussed. [1]. Zhao YS, Weidner DJ, Ko JD, Leinenweber K, Liu X, Li BS, Meng Y,Pacalo REG, Vaughan MT, Wang YB, Yeganehhaeri A,J.Geophys. Res. Solid Earth, 99 (1994) 2871. [2]. Zhao YS, Parise JB, Wang YB, Kusaba K, Vaughan MT, Weidner DJ, Kikegawa T, Chen J, Shimomura O,Am.Miner., 79 (1994) 615.
DE: 3620 Crystal chemistry
DE: 3900 MINERAL PHYSICS
DE: 3924 High-pressure behavior
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting