Mixed (Oxygen Ion and p‐Type) Conductivity in Yttria‐Stabilized Zirconia Containing Terbia

Abstract

Terbia ( or ) has been dissolved into yttria [10 and 8 mole percent (m/o)] stabilized zirconia (Y10SZ and Y8SZ) to form mixed conducting yttria‐stabilized zirconia‐terbia (Y10ZTb and Y8ZTb) solid solutions, with terbia concentrations as high as 50 m/o. The total electrical conductivity between 300 and 800°C in 1 atm oxygen, air, and 10−5 atm has been determined from impedance spectroscopy measurements. Electromotive force cell and oxygen ion blocking electrode techniques have been used to determine oxygen ion transference numbers and p‐type conductivities in air and 1 atm at temperatures between 600 and 833°C. The oxygen‐ion conductivity is more predominant in Y10ZTb and Y8ZTb containing 20 m/o terbia in air at temperatures >650°C, whereas the p‐type electronic conductivity is more predominant in Y10ZTb and Y8ZTb containing 30 m/o terbia. The calculated oxygen ion and electron hole mobilities of Y8ZTb30 at 800°C in air are and , respectively. The activation energies and the calculated electron hole mobility for p‐type conductivity support a small polaron mechanism in these YZTb‐mixed conductors.