Phase stability and electric conductivity of Eu2O3-Tb4O7 co-doped Bi2O3 electrolyte

In this study, eight different samples of Tb4O7 and Eu2O3 co-doped Bi2O3 were prepared by solid-state synthesis techniques. (Bi2O3)1−x−y(Tb4O7)x(Eu2O3)y (x = 5,10; y = 5, 10, 15, 20 mol%) ternary systems were investigated by using X-ray powder diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG), and four-point probe techniques (4PPT). Effect of concentration of doping elements on the temperature and electrical conductivity was investigated. All samples were evaluated by calculating activation energies and average crystal sizes. XRD measurements show that five samples have a single phase (δ-phase) structure. According to electrical conductivity measurements, the conductivity increases with increasing temperature but decreases with increasing amount of Eu2O3. The highest ionic conductivity was measured as 7.28 × 10−1 (ohm.cm)−1 for the (Bi2O3)0.90(Tb4O7)0.05 (Eu2O3)0.05 sample at 850 °C and the lowest activation energy was measured as 0.64 eV for (Bi2O3)0.90(Tb4O7)0.05 (Eu2O3)0.05.