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

Ba0.85Ca0.15Zr0.1Ti0.9O3-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 (TO-T) phase transition shifted towards higher temperature, while Curie temperature (Tc) 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, kp = 34%, εr = 3213, tanδ = 2.71%, Pr = 7.45 µC/cm2 and Ec = 2.75 kV/cm are achieved in the 1 wt% CuO added ceramic sintered at 1250°C for 2 h.