Effect of ratios of dopant contents on the electrical conductivity of Bi2O3 ceramics co–doped with some rare earth oxides

Abstract

In this study, Bi 2 O 3 –based ceramic powders co–doped with differing quantities of Dy 2 O 3 , Sm 2 O 3 , Ho 2 O 3 , and CeO 2 rare earth oxides have been synthesized using the solid state reactions under atmospheric conditions. The XRD patterns revealed that the Dy–rich samples were more effective in stabilizing the cubic δ–phase than the others. The DTA curve of sample S1 (5%Dy: 5%Sm: 5%Ho: 5%Ce) had an endothermic peak at approximately 730 °C, indicating a phase transition from monoclinic α–phase to cubic δ–phase. The conductivity measurements show that sample S11 (10%Dy: 5%Sm: 5%Ho: 5%Ce) had the highest electrical conductivity among cubic δ–phase stabilized samples with 0.027 S/cm at 700 °C. The dopant content ratios, as well as concentration, had a significant impact on electrical conductivity and phase stabilization. According to the SEM images, the grain sizes were not uniform across the surface and decreased as the dopant concentration increased. The EDX pattern of sample S1 verified the presence of all elements in compositions with different peak locations on the pattern and the absence of any peaks indicating impurities. Order-disorder transition (ODT), which is a structural arrangement in the anion sublattice, occurred at approximately 600 °C in Ce-rich samples, according to conductivity plots produced as a function of temperature. • The concentration and type of dopant are critical in stabilizing the high ion conductor cubic δ–phase. • The DTA curve of the sample produced with the lowest concentration of dopant reveals a phase transition from the α–phase to the δ–phase at around 730 °C due to the presence of an endothermic peak on its thermal curve. • The order-disorder transition (ODT), which signifies a structural arrangement of anions in the oxygen sublattice, is only evident in Ce-rich samples. • The FE–SEM images indicate that as the dopant concentrations increase, the porosity along on the surface also begins to rise and the grain boundary line undergoes a significant change.