Structure and electrical properties in CuO-modified BCZT lead-free piezoelectric ceramics

Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃-x wt% CuO (BCZT-xCu) lead-free piezoelectric ceramics were designed and synthesized using a traditional solid-state reaction method to improve both the relaxor behavior and the electrical properties of BCZT lead-free piezoelectric ceramics. The Cu²⁺ diffuses into the BCZT lattice and forms ABO₃ perovskite solid solution. Additionally, X-ray diffraction patterns and Raman spectra reveal that the introduction of CuO causes phase transition from the O-T phase coexistence to the O phase in BCZT-xCu. SEM displays that BCZT-xCu has a well microstructure at CuO doping amount between 0.5 wt% and 1 wt%. With the increasing CuO content, the orthorhombic-tetragonal (T_O-T) phase transition shifted towards higher temperature, while Curie temperature (T_c) shifted towards lower temperature. Moreover, the dielectric diffusivity γ increases from 1.63 to 1.92 as x increases. Results indicate that optimal electrical properties, namely d₃₃ = 315 pC/N, k_p = 34%, ε_r = 3213, tanδ = 2.71%, P_r = 7.45 µC/cm² and E_c = 2.75 kV/cm are achieved in the 1 wt% CuO added ceramic sintered at 1250°C for 2 h.