Effect of Bi2O3 additives in Sc stabilized zirconia electrolyte on a stability of crystal phase and electrolyte properties

Sintering properties, microstructure, crystal phase transformation, electrical conductivity, mechanical strength, and electrolyte performance of Bi2O3-doped Sc2O3-stabilized zirconia prepared by homogeneous precipitation using hydrolysis were investigated. Adding 1 mol% Bi2O3 decreased the sintering temperature of 10 mol% Sc2O3-doped zirconia (10ScSZ) above 300 °C, while accelerating the growth of zirconia grains, so dense sintered ceramics in the cubic phase were formed in a temperature range of 1000–1100 °C. The addition of 1 mol% Bi2O3 to the 10ScSZ inhibited the cubic–rhombohedral phase transformation. Sufficient conductivity of 0.33 S/cm at 1000 °C and 0.12 S/cm at 800 °C for an electrolyte of solid oxide fuel cells (SOFC) was attained for 1 mol% Bi2O3–10 mol% Sc2O3–codoped cubic zirconia (1Bi10ScSZ) sintered at 1200 °C. A maximum power density of 1.61 W/cm2 was obtained at 1000 °C using 1Bi10ScSZ as the electrolyte in SOFC.