Dielectric Properties and Oxide-Ion Conduction for Y 2 O 3 Stabilized ZrO 2 and Bi 2 O 3

The oxide-ion conduction and dielectric properties of 8 mol % Y 2 O 3 stabilized ZrO 2 (8YSZ) and 25 mol % Y 2 O 3 stabilized Bi 2 O 3 (25YSB) which are oxide ion conductors having a fluorite type structure were investigated. The numerical analyses for the frequency dependences of dielectric constants (ε r ') and dielectric loss factors (ε r '') revealed that the dielectric properties were explained by Debye-type polarization due to dopant–vacancy associates and/or polarization due to charging or loss current. No Debye-type polarization was observed in 25YSB because of no effective charge at the Y 3+ -doped Bi 3+ site. On the other hand, three Debye-type dipoles observed in 8YSZ were assigned to the polarization of oxide-ion conduction, and two kinds of associates, [Y Zr '–V o •• ] • and [Y Zr '–V o •• –Y Zr '] × , due to the interaction between doped cation (Y Zr ') and oxygen vacancy (V o •• ). The frequency dependence of dielectric loss tangent (tan δ) in 25YSB was ascribed to the interface loss due to the charged current, while that of tan δ in 8YSZ was ascribed to the Debye-type dipoles in addition to the interface loss.