Excellent dielectric properties and enhanced temperature stability of CaZrO_3-modified BaTiO_3 ceramic capacitors

摘要

x wt% CaZrO_3-BaTiO_3 (x is the wt% of CaZrO_3) was synthesized by a two-step preparation process, using the sol-gel method followed by precipitation. The effect of CaZrO_3 content on the ceramic composition, structure, and dielectric performances was systematically investigated. The X-ray diffraction analysis results show that the structure of x wt% CaZrO_3-BaTiO_3 ceramics changed from tetragonal phase to pseudocubic phase with increasing CaZrO_3 content. The addition of CaZrO_3 effectively decreased the sintering temperature of BaTiO_3 ceramics and promoted the ceramic grain growth. The ceramic density increases first and then decreases with increasing CaZrO_3 content. The dielectric performances of ceramics were optimal at a CaZrO_3 content of 8 wt%. Owing to its larger grain and intensity of polarization, 8 wt% CaZrO_3-BaTiO_3 shows that a stable high permittivity (7145), a low dielectric loss (0.004), and the ceramic temperature coefficient of capacitance (TCC) values were within ±22% in the range of-55 to 150 °C, thus meeting to Electronic Industries Alliance (EIA)-X8S regulations. The experimental results indicate that this two-step preparation process is an extremely effective method to enhance the ceramic dielectric performances, and adding a small amount of CaZrO_3 effectively reduced the TCC absolute value of ceramics.