The O non-stoichiometry of Mn-doped polycrystalline BaTiO3-δ was measured as a function of O partial pressures in the range of 10-16 to 0.1, at 900 to 1100, by using a solid-state bolometric titration technique. The extent of non-stoichiometry of Mn-doped BaTiO3 was much larger than that of undoped BaTiO3, and was attributed to defect-chemical role of Mn as acceptors. The non-stoichiometry isotherms indicated that Mn-ions changed their valence from +4 (or MnTix) to +3 (or MnTi’) to +2 (or MnTi’’) with decreasing PO2.

Nonstoichiometry and Defect Structure of Mn-Doped BaTiO3-δ. D.K.Lee, H.I.Yoo, K.D.Becker: Solid State Ionics, 2002, 154-155, 189-93