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

Abstract

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.