Thermal Expansion and Electrical Characteristics of Ba(1−x)CaxTi0.92Zr0.08O3 Lead-Free Ceramics Prepared by a Modified Pechini Method
Ba(1−x)CaxTi0.92Zr0.08O3 (BTZ-xCa; x = 0–0.20) lead-free ceramics were prepared at a low temperature of 1210°C using as-synthesized nanoparticles through a modified Pechini method. The structure, permittivity, ferroelectricity, piezoelectricity, and thermal expansion characteristics of the ceramics that were influenced by varying calcium contents were studied in detail. X-ray powder diffraction and Raman results suggested that calcium could not induce the rhombohedral phase transition, and impurity phases were detected with excessive x. The electrical properties were basically elevated firstly in the room temperature direction of the temperature of phase transitions for orthorhombic-to-tetragonal with weaker internal stress, and then they apparently deteriorated with the shrunk octahedron size and strongly distorted structure with an increase of calcium content. The optimum electrical properties, i.e., d33, kp, and Qm of the BTZ-xCa ceramics were 261 pC/N, 24.9%, and 98 were obtained when the calcium content was 0.05, respectively. Additionally, the thermal expansion coefficient was studied for providing guidance on the ceramic materials production and usage.