Structure of Single-Crystal Rutile (TiO2) Prepared by High-Temperature Ultracentrifugation

We report the preparation of single-crystal rutile (TiO2) with a unique structure prepared by ultracentrifugation at high temperature (strong gravitational field). Single-crystal rutile was subjected along the c-axis direction to a gravitational field of 0.4 × 106 G at 400 °C, and the uniquely structured single-crystal rutile, which did not conform to Pauling’s third rule, was quenched at ambient conditions. The anisotropy (a/c ratio) of the tetragonal phase increased by 2%. The (Ti–Oa)/(Ti–Ob) and Os/Ou ratios increased by 1.6% and 3%, respectively, and approached 1; Ti–Oa and Ti–Ob are the two Ti–O interatomic distances, and Os and Ou are the shared edge Oa–Oa and the unshared edge Oa–Ob, respectively. This means that the TiO6 octahedral group became isotropic. Os was expanded from its normal size, in contradiction to the usual laws, by the strong gravitational force. Such a structural change has not previously been achieved under high-pressure or high-temperature conditions, and may be related to struc...

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