Prediction of electronic, structural and elastic properties of the hardest oxide: TiO₂

This work combines the theory of elasticity with first principles quantum mechanic calculations to predict the electronic, structural and elastic properties: elastic constants, bulk moduli of the TiO₂ (Titania) in the Pnma phase. Band-structure shows a direct gap in Γ which increases its value under hydrostatic pressure. It has two regimes: in the range 0–50 GPa the band-gap has a negative second pressure derivative and changes its sign in the range 50–100 GPa. The band gap becomes indirect at pressures above 150 GPa. This phase improves its mechanical stability and insulator properties under extreme conditions of hydrostatic pressures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)