Electrical Conductivity of Sm₂O₃-ZrO₂ and Yb₂O₃-ZrO₂ Solid Solutions

Abstract

Electrical conductivities of the Sm₂O₃-ZrO₂ and Yb₂O₃-ZrO₂ solicl solutions containing 10∼50mol% of each rare earth oxide were measured. The electrical conductivity of the Sm₂O₃-ZrO₂ system decreased and its apparent activation energy increased with increasing Sm₂O₃ content. The structural change from fluorite to pyrochlore phase increased the conductivity, and a conductivity maximum and an activation energy minimum were found at 25∼30 mol% and 30mol% of Sm₂O₃, respectively. However, the Yb₂O₃-ZrO₂ system which does not have pyr ochlore phase showed neither the conductivity maximum nor the activation energy minimum. The ionic transport number of the sample which showed the conductivity maximum (Sm₂O₃: 25 mol%) was measured with an oxygen concentration cell. The ionic transport number was higher than O.9 in a wide range of temperature and partial pressure of oxygen.