Abstract: The defect chemistry of BaPbO₃ was studied by the measurement of the equilibrium electrical conductivity as a function of oxygen pressure (10^-12-10⁵ Pa). The major defects and their charge-compensating defects in undoped and acceptor-doped BaPbO₃ were present. The influence of impurities concentrations on equilibrium electrical conductivity and both inflexions of the change of major defects in high and low oxygen-activity regions were discussed. At highly oxygen activity the major defects are lead vacancies and their compensating holes. With the decreasing in oxygen activity, the major defects will change from intrinsic disorder into
extrinsic disorder and the acceptor impurities become the major source of defects. At lower oxygen activity the oxygen vacancies become compensating defects instead of the holes, and the reducing reaction becomes the major source of compensating defects. Both inflexions in high and low oxygen-activity regions move to higher oxygen activity with the increasing of acceptor concentrations.

Key words: BaPbO₃, defect chemistry, nonstoichiometry, acceptor