Defect Chemistry of Y Doped BaTiO3

Defect chemistry of Y doped BaTiO₃ was investigated as a function of the Ba/Ti ratio. When the Ba/Ti ratio was greater than unity, Y^{3 +} was substituted for the normal Ti site and the equilibrium conductivity showed a strong evidence of acceptor-doped behavior. With the Ba/Ti ratio < 1, Y^{3 +} was substituted for the Ba site and the equilibrium conductivity showed donor-doped behavior. In the case excess Y₂O₃ was added to the stoichiometric BaTiO₃(Ba/Ti = 1), the conductivity profile showed a donor-doped behavior at low concentrations (< 1.0 mol%), whereas, at higher donor levels (> 2.0 mol%), the equilibrium conductivity minimum shifted toward lower Po₂, indicating acceptor doped behavior.