Defect chemistry in perovskite ferroelectrics—History, present status, and future prospects—

Perovskite ferroelectrics such as BaTiO3 and PbTiO3 provide various functions arising from spontaneous polarization. Here, the history, present status, future prospects of defect chemistry for are described. Even non-doped samples, unintentional impurities including Fe govern its related properties. By solving multiple nonlinear equations employing thermodynamic data set reported, majority/minority defect-concentration diagrams available not only in a high-temperature equilibrium state but also low-temperature quenched one. As an example, Ba(Ti,Ca)O3 Ba(Ti,Mn)O3 shown, roles fixed valence (Ca) variable-valence (Mn) acceptors explained. I introduce example control single crystals; activation visible-light photovoltaic effect, where two redox potentials derived Fe2+ Fe3+ act scaffolds generating electron–hole pairs.