Cotunnite-Structured Titanium Dioxide and the Hardest known Oxide |
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| Authors: | Rajeev Ahuja Leonid S Dubrovinsky |
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| Institution: | 1. Condensed Matter Theory Group, Department of Physics , Uppsala University , Box 530, Uppsala , S-751 21 , Sweden Fax: E-mail: rajeev@fysik.uu.se;2. Institute of Earth Sciences , Uppsala University , Uppsala , S-752 36 , Sweden |
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| Abstract: | Combined theoretical and experimental investigations led to the discovery of a new polymorph of titanium dioxide with titanium nine-coordinated to oxygen in the cotunnite (PbCl 2 ) structure. Hardness measurements on the cotunnite-structured TiO 2 synthesized at pressures above 60 GPa and temperatures above 1000 K reveal that this material is the hardest oxide yet discovered. Furthermore, it is one of the least compressible (with a measured bulk modulus of 431 GPa) and hardest (with a microhardness of 38 GPa) polycrystalline materials studied thus far. |
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| Keywords: | High Pressure Hard Material Phase Transition Fplmto Total Energy |
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