Solid State Ionics, Vol.154, 189-193, 2002
Nonstoichiometry and defect structure of Mn-doped BaTiO3-delta
Oxygen nonstoichiometry (delta) of 1 m/o Mn-doped polycrystalline BaTiO3-delta has been measured as a function of oxygen partial pressure in the range of 10(-16) less than or equal toP(O2)/atmless than or equal to0.1 at elevated temperatures (900less than or equal toT/degreesCless than or equal to1100) by a solid-state coulometric titration technique. The extent of nonstoichiometry of Mn-doped BaTiO3 is much larger than that of undoped BaTiO3, which is attributed to defect-chemical role of Mn as acceptors. The nonstoichiometry isotherms indicate that Mn-ions change their valence from +4 (or Mn-Ti(X)) to +3 (or Mn-Ti') to +2 (or Mn-Ti'') with decreasing P-O2.
Keywords:Mn-doped BaTiO3-delta;oxygen nonstoichiometry;coulometric titration;defect structure;valence state of manganese