Microstructure, Crystal Lattice, Electrical and Magnetic Properties of Bi2O3 Ceramics Doped with Some Rare Earth Oxides Depending on Doping Ratios

In this study, Bi2O3-based ceramic powders doped with different amounts of some rare earth oxides (Dy2O3, Sm2O3, Ho2O3 and CeO2) were synthesized using solid-state reactions under atmospheric conditions. 5Dy5Sm10Ho5Ce (A1 - 5% Dy: 5% Sm: 5% Ho:5 % Ce, 1:1:1:1) sample has both δ-Bi2O3 and cubic CeO2 phases. However, δ -Bi2O3 cubic phase peaks predominate. The δ-Bi2O3 cubic phase has a unit cell parameter of 5.525 Å and the CeO2 cubic phase has a unit cell parameter of 5.411 Å. The conductivity measurements showed that among the samples of which cubic δ phase is stabilized at 900 °C, the A1 sample has the highest electrical conductivity with 4.05x10-1 S/cm. The XRD measurement for 5Dy5Sm15Ho5Ce (A2-5% Dy: 5% Sm: 10% Ho: 5% Ce, 1:1:2:1) showed that, the (hkl) parameters obtained from the XRD peaks of Bi2O3 shifted very little as the amount of Ho increased and it has left its place to the Bi1.5Ho0.5O3 cubic phase structure. The Bi1.5Ho0.5O3 cubic phase has a unit cell parameter of 5.497 Å. In addition, the increase in the contribution rate resulted in the maintenance of this phase. The miller indices of the most intense peaks for both Bi1.5Ho0.5O3 and Bi2O3 were determined as (111), (200), (220) and (311). Additionally, according to FE–SEM pictures acquired at 5 μm and 2 μm distances, grain size is not uniform throughout the surface, and the grain boundary line varies sharply as dopant concentration increases. According to SEM images, grain sizes are not uniform across the surface and decreased as the additive concentration increased. Magnetization measurements revealed a paramagnetism at room temperature and very low temperatures.