WANG Jun, JIANG Xiangping, CHEN Chao, NIE Xin, HUANG Xiaokun, ZHENG Laiqi, WANG Xianwen

(School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333403, Jiangxi, China)

Abstract: Lead-free piezoelectric ceramics, (Na_0.47Bi_0.47Ba_0.06))Ti_1-xCu_xO₃ (NBT-6BT-xCu²⁺ , 0≤x≤0.025), were synthesized by using the conventional solid-state reaction method. Phase composition and electrical properties of the Cu²⁺ -doped NBT-6BT-xCu²⁺ ceramics were systematically studied. It was found that grain size of the ceramics was dependent on the concentration of CuO. X-ray diffraction (XRD) data indicated that Cu²⁺ was dissolved into the lattice of the ceramics forming single phase perovskite. XRD Rietveld refinement results confirmed that all the samples consisted of monoclinic (Cc) and tetragonal (P4bm) phases, with a typical morphotropic phase boundary (MPB) structure. The presence of Cu²⁺ had an effect on the phase content of Cc and P4bm in the MPB，demonstrating a positive influence on piezoelectric and ferroelectric properties of the ceramics. The ceramics doped with 1.5 wt.% CuO showed optimal performance with a piezoelectric constant (d₃₃) of 178 pC/N and a remnant polarization (Pr) of 42.93 µC/cm². It was therefore concluded that Cu²⁺ can be used to improve the electrical properties of (Na_0.47Bi_0.47Ba_0.06)TiO₃ lead-free ceramics through adjusting the phase content at MPB.

Key words: piezoelectric ceramics; (Na_0.47Bi_0.47Ba_0.06)TiO₃ ; morphotropic phase boundary; piezoelectric constant