受主掺杂BaPbO_3陶瓷的缺陷结构

Defect Structure of Acceptor-doped BaPbO_3 Ceramics

采用高温平衡电导法测定高温平衡电导率随氧分压(10-12～105Pa)的变化曲线,阐明了受主掺杂BaPbO3的缺陷结构,解释了材料的导电机理.高氧分压下,Pb离子空位缺陷占主导,电荷补偿缺陷为空穴;随着氧分压的下降,材料由本征缺陷占主导向杂质缺陷占主导转变,受主杂质成为主导缺陷,电荷补偿缺陷为空穴;在低氧分压下,电荷补偿缺陷由空穴转变为氧离子空位.受主掺杂浓度的下降,导致高温电导率下降,并引起本征缺陷占主导向非本征缺陷占主导的转变点向低氧分压方向移动,同时低氧分压区域的电荷补偿缺陷由空穴转变为氧离子空位的转变点也向更低的氧分压方向移动.

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^-12～10^5 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.