HR: 0800h
AN: DI41A-0342    [Abstracts]
TI: High-Pressure Phase Diagram of TiO2 as Determined by Experiment and Theory
AU: * Al Khatatbeh, Y M
EM: yahya@nmsu.edu
AF: New Mexico State University, Department of Physics, MSC 3D, Las Cruces, NM 88003- 8001, United States
AU: Lee, K K
EM: kanani@physics.nmsu.edu
AF: New Mexico State University, Department of Physics, MSC 3D, Las Cruces, NM 88003- 8001, United States
AU: Kiefer, B
EM: bkiefer@nmsu.edu
AF: New Mexico State University, Department of Physics, MSC 3D, Las Cruces, NM 88003- 8001, United States
AB: We have investigated the high-pressure phase diagram and determined the equations of state (EOS) of TiO₂ using high-resolution synchrotron x-ray diffraction and complementary ab-initio computations. The phase sequence we observe experimentally is as follows: rutile → columbite → baddeleyite → orthorhombic I (OI), and additional high-pressure structures. Upon compression at room temperature, rutile was observed to be stable up to about 17 GPa, but reflections from baddeleyite were observed at about 12 GPa and persisted to 50 GPa. Upon decompression from 17 GPa (without heating), the baddeleyite phase transformed to columbite at ~ 8 GPa. Columbite remained stable as the pressure was decreased further. Additionally, we have heated our sample at pressures 30, 35, 40, and 50 GPa to ~ 1800 K and found that baddeleyite transforms to OI at 30 and 35 GPa. Finally, the EOS's determined experimentally will be compared with those determined computationally.
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting