Distortions in Octahedrally Coordinated d⁰ Transition Metal Oxides:  A Continuous Symmetry Measures Approach

More than 750 d⁰ transition metal oxide octahedra have been examined in order to better understand the out-of-center distortion occurring with these cations. A continuous symmetry measures approach was used to quantify the magnitude and direction of the distortion. Using this approach we were able to divide the d⁰ transition metals into three categories:  strong (Mo⁶⁺ and V⁵⁺), moderate (W⁶⁺, Ti⁴⁺, Nb⁵⁺, and Ta⁵⁺), and weak (Zr⁴⁺ and Hf⁴⁺) distorters. We also examined and discussed the directional preference of the distortion for each cation.