Effects of strontium gallate addition on sintering behavior and electrical conductivity of yttria-doped ceria

The densification behavior and electrical conductivity of Ce_0.8Y_0.2O_1.9 ceramics with strontium gallate concentrations ranging from 0 to 5 mol. % were investigated. The sintered density was found to increase rapidly for concentrations up to 0.5 mol. % Sr₂Ga₂O₅ and then to decrease upon further Sr₂Ga₂O₅ addition. It was possible to obtain dense Ce_0.8Y_0.2O_1.9 ceramics with 95% of the theoretical density using a 0.5 mol. % Sr₂Ga₂O₅-added specimen sintered at 1250°C for 5 h, whereas pure Ce_0.8Y_0.2O_1.9 ceramics needed to be sintered at 1550°C in order to obtain an equivalent theoretical density. The electrical conductivity was measured as a function of the dopant content over the temperature range of 450°C-700°C in air. The conductivity of the 0.5 mol. % Sr₂Ga₂O₅-added specimen showed a maximum value of 4.43 × 10^-3 Ω ^-1·cm^-1 at 700°C. The addition of Sr₂Ga₂O₅ was found to promote the sintering properties and electrical conductivities of Y₂O₃-doped CeO₂.