Synthesis and Crystal Structure Analysis of Tetragonal Phase Bismuth Oxide-Based Solid Electrolytes with Double Doping Method

In this study, Yb₂O₃ and Er₂O₃ were doped into Bi₂O₃ using the solid-state reaction method to investigate their effects on the structural and electrical properties of the material for solid oxide fuel cell (SOFC) applications. Structural characterization was conducted using X-ray diffraction (XRD), while electrical conductivity was measured via a four-point probe method across a temperature range of 300–810 °C. The influence of dopant concentration on phase stabilization, grain morphology, and ionic conductivity was systematically studied. The results revealed that β-phase tetragonal Bi₂O₃ was successfully stabilized, and Yb-doping significantly enhanced ionic conductivity, particularly at elevated temperatures. SEM analysis further elucidated the role of grain size and porosity on the conductivity behavior.