Herein, we developed a novel double dopant bismuth oxide electrolyte system with dysprosium (Dy) and gadolinium (Gd). The effect of the co-dopants on phase stability and electrical properties was investigated. Phase transformation from cubic to rhombohedral was observed as Gd dopant concentration increased and consequently resulted in conductivity degradation. The stabilization of high temperature cubic phase was achieved with a total dopant concentration as low as ∼12 mol% with 8 mol% Dy and 4 mol% Gd double dopant composition (8D4GSB) and this composition showed one of the highest total conductivity reported at this low temperature regime. In addition, the long-term stability of DGSB electrolytes was investigated.
