A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the mineral called perovskite, which consists of calcium titanium oxide . The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski . 'A' and 'B' are two positively charged ions , often of very different sizes, and X is a negatively charged ion that bonds to both cations. The 'A' atoms are generally larger than the 'B' atoms. The ideal cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite forms may exist where either or B1y-1B2y and the X may deviate from the ideal coordination configuration as ions within the A and B sites undergo changes in their oxidation states.