Microstructural evolution and dielectric properties of Cu-deficient and Cu-excess CaCu_3Ti_4O_(12) ceramics

摘要

The microstructural evolution and dielectric properties of CaCu_(1-x)Ti_4O_(12-x) (3 - x = 2.8-3.05) ceramics were investigated. Normal grain growth behavior was observed at Cu/Ca ≤ 2.9, while abnormal grain growth was observed at Cu/Ca ≥ 2.95. A CuO-rich intergranular liquid phase at Cu/Ca ≥ 2.95 and angular grain morphology were the main reasons for abnormal grain growth. However, the abundant intergranular liquid at Cu/Ca = 3.05 significantly affected the relative dielectric permittivity and dielectric loss. The CuO composition is the key parameter that determines the microstructure and dielectric properties of CCTO ceramics.