Enhanced dielectric and electrical properties in CaZrO_3-doped X8R BaTiO_3-based ceramics sintered at medium temperature

摘要

Lead-free X8R BaTiO_3-based ceramics were prepared by conventional solid-state method. The influence of the composition and procedures on the microstructures, lattice parameters and dielectric properties of ceramics materials were systemically studied. XRD results indicate that no secondary phase is formed in the CaZrO_3-doped samples after sintering. The content of Ca~(2+) ions and Zr~(4+) ions decrease from grain boundaries to grain interiors referring to EDS results, which indicate that the ions mainly locate in the grain boundaries. The Curie temperatures of all CaZrO_3 doped samples increase due to the increasing tetragonality caused by the addition of CaZrO_3. SEM micrographs reveal that the grain size of CaZrO_3-doped BaTiO_3-based samples are not uniform, ranging from 0.2 to 0.8 μm. Furthermore, samples doped with 1.0 wt % CaZrO_3 exhibit optimal dielectric properties with high temperature stability of capacitance, due to the fine-grain microstructures. Moreover, we obtained a lead-free high performance X8R dielectric ceramic composition sintered at medium temperature (1,135 ℃).