Structure–property relationships in Sm–Eu–Yb co-doped δ-Bi₂O₃ ceramics synthesized for advanced solid electrolyte applications

Year 2026, Issue: 064 , 48 - 59 , 30.03.2026

Yasin Polat

https://doi.org/10.59313/jsr-a.1695279

https://izlik.org/JA25LD28DR

Abstract

In this study, we investigated the structural, thermal, and electrical properties of Sm³⁺–Eu³⁺–Yb³⁺ co-doped bismuth oxide (Bi₂O₃) ceramics for use as solid electrolytes in intermediate-temperature solid oxide fuel cells (IT-SOFCs). Solid solutions with the formula (Bi₂O₃)₁₋ₓ₋ᵧ₋_𝓏(Sm₂O₃)ₓ(Eu₂O₃)ᵧ(Yb₂O₃)_𝓏 were synthesized via solid-state reaction and sintered at 750 °C for 100 hours. X-ray diffraction (XRD) analysis confirmed the formation and retention of the high-conductivity δ-phase structure after high-temperature electrical testing. Dense and uniform microstructures were observed by SEM, with only minor grain coarsening when relatively high amounts of Yb³⁺ were incorporated into the ceramic materials. TG/DTA data confirm the thermal stability of these materials as they exhibit very little mass loss and no phase transitions to 850 °C. The electrical conductivity data demonstrate thermal activation of conduction, with the most conductive samples containing 5 mol% Yb₂O₃; further addition of Yb₂O₃ caused clustering of defects, which resulted in reduced conductivities. The results of this investigation further demonstrate that triple-doping with rare-earth oxides can effectively provide thermal and structural stability to the δ-Bi₂O₃ phase and, therefore, allow for the development of thermally and structurally stable electrolytes as potential candidates for IT-SOFCs. This work provides the basis for the use of these sustainable functional ceramics in future energy applications.

Keywords

Intermediate-temperature solid oxide fuel cells , δ-Bi₂O₃ stabilization , rare-earth co-doping , electrical conductivity , solid-state synthesis

Thanks

The author would like to acknowledge the support of Nevşehir Hacı Bektaş Veli University Center for Science and Technology Application and Research for providing the measurement facilities used in this study.

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