Properties of ionic-conducting β-Bi₂O₃ containing mixed dopants

β-Bi₂O₃ compositions were prepared to evaluate the effect on properties of using mixed dopants. Baseline compositions containing 28 mol% of the alkaline-earth oxides CaO, SrO, or BaO were used for comparison. When the alkaline earths were combined in pairs to dope the bismuth oxide, the resulting properties were intermediate between the baseline end members. The data suggest that the transformation temperature for forming the high-conductivity β₁ phase can be varied continuously over a temperature range of about 565° to 750°C. Utilization of additional additives having different ionic size or valence charge compared with the alkaline earths resulted in an observed property changes that could be attributed to the additive alone. The most important variables influencing the conductivity level and phase transformation temperature of β-Bi₂O₃ were the type and the amount of the alkaline-earth dopant in the composition.