Investigation of structural, thermo–electrical, and morphological features of the (Bi2O3)1–x–y (Tm2O3)x (Yb2O3)y ternary systems for intermediate temperatures

• Published in: Solid state ionics 2024-09, Vol.412, p.116583, Article 116583
• Main Authors: Balci, Murat, Payveren, Mehtap Arikan, Saatci, Buket, Ari, Mehmet
• Format: Article
• Language: English
• Subjects: Crystal size; Electrical activation energy; Grain boundary; Order–disorder transition; Phase transition
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2024.116583

In this paper, the (Bi2O3)1–x–y (Tm2O3)x (Yb2O3)y ternary systems were successfully synthesized by the solid–state reaction method under air conditions. All powder compositions were then heat treated for 100 h at 750 °C to allow for partial substitution of dopant cations, Tm3+ and Yb3+, between host Bi3+ cations. Characterizations of fabricated compositions were carried out by XRD, TG and DTA, FPPT, and FE–SEM techniques. Stacked XRD patterns verified that all compositions included solely single–phase peaks, with the exception of Bi0.92Tm0.04Yb0.04O1.5–δ and Bi0.88Tm0.04Yb0.08O1.5–δ, whose patterns suggested mixed phases. The DTA curves, depending on temperature, detected the endothermic peaks at around 600 °C, implying that an order–disorder transition occurs in the anion sublattice of the doped crystal. At 700 °C, the conductivity of the Bi0.88Tm0.08Yb0.04O1.5–δ system was found to be 0.432 S/cm, surpassing the conductivity of a single–doped (Bi2O3)0.80 (Er2O3)0.20 system, which had a value of 0.37 S/cm at the same temperature. •The cubic δ-phase with high ion conductivity became stable in the majority of fabricated compositions.•The magnified XRD patterns indicated a peak shift because of doping.•The DTA curves reveal the endothermic peaks at around 600 °C, signifying an order-disorder transition.•The highest conductivity is found to be 0.432 S/cm at 700 °C for the Bi0.88Tm0.08Yb0.04O1.5–δ composition.•The order-disorder transition is noticeable on the Arrhenius plots at around 600 °C.