Improvement of dielectric properties of La/Bi co-substituted BaSm₂Ti₄O₁₂ ceramic for capacitor application

For capacitor applications, Ba(Sm_1-x-yLa_xBi_y)₂Ti₄O₁₂ dielectric ceramics with La/Bi co-substitution for Sm were prepared using the conventional solid-state method. Part of Sm³⁺ was found to be replaced by La³⁺ and Bi³⁺ in ceramics that exhibit an orthorhombic tungsten bronze structure. As the concentration of Bi³⁺ increased, a second phase of Bi₄Ti₃O₁₂ was observed. The co-substitutions could reduce the sintering temperature and effectively increase the dielectric constant from 80 to 140. The dielectric loss increased slightly with increasing La³⁺ and Bi³⁺, but it still remained below 0.1% at 1 kHz. After sintering, a specific composition was achieved with x = 0.1 and y = 0.4. It has a high dielectric constant of 132, an ultra-low dielectric loss of approximately 0.06%, and excellent frequency stability. Additionally, it exhibits a capacitance-temperature change of ± 1% at 1 kHz over a temperature range of − 55 to 125 °C.