Phase structure and electrical properties of (1−x−y)K1−z NazNbO3−x(0.8Bi0.5Na0.5ZrO3−0.2Bi0.5K0.5ZrO3)−yBiFeO3 lead-free ceramics

(1−x−y)K1−z NazNbO3−x(0.8Bi0.5Na0.5ZrO3−0.2Bi0.5K0.5ZrO3)−yBiFeO3 lead-free ceramics were prepared by the conventional solid–state reaction process. In this work, we presented the evolutions of their phase structure and electrical properties by tailoring the compositions in KNN-based ceramics. By considering the XRD and εr−T curves, a rhombohedral-orthorhombic-tetragonal (R–O–T) phase structure is identified in the composition region of 0.04 ≤ x < 0.05, 0.005 ≤ y ≤ 0.006 and 0.40 < z < 0.55, and the enhanced electrical properties (e.g., d33~405 pC/N, kp~0.485, TC~321 °C, strain ~ 0.16% and d33*~515 pm/V) was obtained in the ceramics of x = 0.04, y = 0.006, z = 0.50. Moreover, a good thermal stability was also observed in the ceramics. Therefore, such a research can benefit the sustainable development of KNN-based for the practical piezoelectric devices.