Evolution of phase structure, microstructure, and electrical properties in (1 − x)(K,Na)NbO3-x(Bi,Na,Li,Ba)ZrO3 lead-free ceramics

The (1 − x)K0.48Na0.52NbO3-x[Bi0.5(Na0.875Li0.125)0.5]0.94Ba0.06ZrO3 [(1 − x)KNN-xBNLBZ] ceramics were prepared by the conventional solid-state method, and the effects of BNLBZ content on their phase structure, microstructure, and electrical properties were studied. The doping with BNLBZ shrinks its rhombohedral-orthorhombic (R-O) and orthorhombic-tetragonal (O-T) phase transitions, that is, TR-O increases and TO-T decreases as the BNLBZ content increases. Finally, the mixed phases consisting of R, O, and T were involved into the ceramics with 0.04 ⩽ x ⩽ 0.055. The ceramics with x = 0.04 have a grain bimodal distribution, and then the dense microstructure was also developed. In addition, the ceramics possess the enhanced electrical properties (e.g., d33 ∼ 235 pC/N, kp ∼ 51%, Pr ∼ 20.98 μC/cm2, and Ec ∼ 12.26 kV/cm). As a result, this material system is one of the most promising candidates in the field of lead-free piezoelectrics.