The defect chemistry of BaPbO₃ was studied by measurement of the equilibrium electrical conductivity by a four-probe dc technique as a function of oxygen pressure (10^－12～10⁵ Pa). A defect model for acceptor-doped BaPbO₃, which emphasized the role of impurities, was presented. The conduction mechanism is interpreted based on the defect structure of BaPbO₃. At high oxygen activity the condition of charge neutrality will be dominated by the lead vacancies and their compensating holes. The major defects will change from intrinsic disorder into extrinsic disorder with the decrease in oxygen activity. The acceptor impurities become the major defects and the compensating defects are holes. In the lower oxygen-activity region the compensating defects change from holes into oxygen vacancies. The decrease of the concentrations of acceptors resulted in the reducing of the equilibrium conductivity and moved both inflections at high oxygen activity and low oxygen activity to lower oxygen activity.

Key words: BaPbO₃, defect chemistry, compensating defect, acceptor, equilibrium conductivity