Mechanical properties, hardness and electronic structures of new post-cotunnite phase (Fe2P-type) of TiO2

Based on the first-principles calculations, we investigate mechanical properties, hardness and electronic structures of the new Fe2P-type TiO2. The computed equilibrium lattice constants and mechanical moduli of Cotunnite-TiO2 are in agreement with those experimental values and previous calculated data. The mechanical moduli (bulk, shear and Young's moduli) are evaluated by Voigt–Reuss–Hill approach. We plot the planar contours of bulk and Young's moduli of Fe2P–TiO2 structure at several crystallographic planes ((001) and (100)) to reveal their anisotropy in elasticity. The Šimůnek's method is applied to calculate the Vickers hardness of Fe2P-type of TiO2. Moreover, Fe2P–TiO2 shows strong ionicity from the computed angular momentum projected density of states. The computed hardness of Fe2P–TiO2 is below 20GPa.