受主掺杂BaPbO_3中的非化学计量比

Nonstoichiometry in Acceptor-doped BaPbO_3

采用高温平衡电导法测定了高温平衡电导率随氧分压(10^(-12)～10~5Pa)的变化曲线,由此确定了未掺杂和Al受主掺杂BaPbO_3陶瓷多晶体中的主导缺陷及其电荷补偿缺陷.同时讨论了受主掺杂浓度对材料的高温平衡电导率、高氧分压和低氧分压下主导缺陷转变点的影响,确定了受主掺杂BaPbO_3缺陷行为随掺杂量的变化机理.在高氧分压下,材料表现出本征缺陷行为,Pb离子空位占主导,电荷补偿缺陷为空穴;随着氧分压的下降,材料由本征缺陷控制区域进入非本征缺陷控制区域,受主杂质取代Pb离子空位占主导;在低氧分压区域,随着氧离子空位浓度的上升,氧离子空位取代空穴,成为受主杂质的电荷补偿缺陷.

The defect chemistry of BaPbO3 was studied by the measurement of the equilibrium electrical conductivity as a function of oxygen pressure （10^-12-10^5 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.