An investigation on the phase formation and electrical properties of Bi2O3 ceramics co–doped with Ce–Ho–Tb rare earths

• Published in: Journal of solid state chemistry 2024-01, Vol.329, p.124447, Article 124447
• Main Authors: Balci, Murat, Payveren, Mehtap Arikan, Saatci, Buket, Ari, Mehmet
• Format: Article
• Language: English
• Subjects: Electrical conductivity; Lattice shrinkage; Order–disorder transition; Peak shifting; X–ray diffraction
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2023.124447

In this paper, Ce–Ho–Tb co–doped Bi2O3 compositions were developed using the solid–state reaction method under atmospheric conditions. The XRD patterns confirm the stability of the cubic δ–phase in Ho and Tb–rich compositions but not in the Ce–rich ones, which consist of mixed phases, such as α and β. Peak shifting is additionally apparent in the magnified XRD diagram of primary peaks regarding the (111) diffraction plane, suggesting that the structural features change with doping. At 700 °C, the highest conductivity is found to be 0.30 S/cm for the composition 8Ce4Ho4Tb, and it is comparable to the single–doped (Bi2O3)0.80(Er2O3)0.20 system at the same temperature. The FE–SEM images show the aggregation, particularly in images of Ce–rich compositions, implying that large cations have difficulty penetrating the lattice. The porosity over the surface is dense, particularly for Tb–rich compositions, indicating a decline in conductivity with doping. The cubic δ–phase of Bi2O3 crystal, an excellent ion conductor, is capable of being stabilized at room temperature in Ho-rich compositions. Arrhenius plots of conductivity clearly show that the content ratios of 1:2:1, which is a specific ratio, play a key role in achieving the highest conductivity stable Bi2O3 electrolytes. [Display omitted] •A high ion conductor, δ-Bi2O3 phase was effectively stabilized in Ho and Tb-rich compositions.•The highest conductivity was determined to be 0.30 S/cm, which is greater than 20ESB electrolyte.•In several compositions, the order-disorder transition on the Arrhenius plots is noticeable.•The FE-SEM pictures revealed a local aggregation on the surface, particularly in the Ce-rich specimens.