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arXiv · 0907.1464

Cotunnite-structured titanium dioxide: the hardest known oxide

L. S. Dubrovinsky·N. A. Dubrovinskaia·V. Swamy·J. Muscat·N. M. Harrison·R. Ahuja·B. Holm
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Abstract

Despite great technological importance and many investigations, a material with measured hardness comparable to that of diamond or cubic boron nitride has yet to be identified. 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 (PbCl2) structure. Hardness measurements on the cotunnite-structured TiO2 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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L. S. Dubrovinsky, N. A. Dubrovinskaia, V. Swamy, J. Muscat, N. M. Harrison, R. Ahuja, B. Holm. 2009-07-09. Cotunnite-structured titanium dioxide: the hardest known oxide. https://arxiv.org/abs/0907.1464

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