Effect of samarium and lanthanum co-dopant on the microstructure and dielectric properties of BaZr_0.2Ti_0.8O₃ ceramics

The BaZr_0.2Ti_0.8O₃ ceramics with perovskite structure were prepared by solid state reaction method with addition of x La₂O₃ and x La₂O₃ + 0.2 wt% Sm₂O₃ (x = 0.0, 0.1 and 0.4 wt%). Microstructure and dielectric behaviour of the obtained ceramics were respectively investigated. The compositions of these ceramics demonstrated a single-phase cubic symmetry in a room-temperature X-ray diffraction study. The dielectric constant peak of those samples with addition of x La₂O₃ and x La₂O₃ + 0.2 wt% Sm₂O₃ greatly reduced along with increasing x. Simultaneously, a drastic increase of the values of γ was also observed when x rose, exhibiting a diffuse phase transition. T _m increased along with increasing La content for x La₂O₃ doped BZT20 ceramics, but decreased along with increasing La content for x La₂O₃ + 0.2 wt% Sm₂O₃ doped BZT20 ceramics. Owing to the doping of Sm³⁺, the x La₂O₃ + 0.2 wt% Sm₂O₃ doped BZT20 ceramics have maintained very low and stable dissipation factors under an increasing environment temperature, making them superior candidates for applications.