Ferroelectricity in Perovskite-Type Oxides

Ferroelectricity in perovskite-related oxides was briefly reviewed mainly from the view point of crystal chemistry. Tolerance factor, t, for perovsikte oxides clearly discriminates the dielectric properties of them, except for KTaO. B-site off-center and BO6 tilting become dominant for t 1 and t 1, respectively. Only BaZrO3 and SrTiO3 sit on t = 1.00. A-O covalent bonding seems essential for the evolution of ferroelectricity in ABO3 perovskites, especially for the compounds with t 1.