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

For capacitor applications, Ba(Sm1-x-yLaxBiy)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 degrees C.