Crystal structures and electrical properties of (1 − x)K 0.5Na 0.5NbO 3– xBi 0.8La 0.2FeO 3 lead-free ceramics

Abstract

A series of lead-free piezoceramics of (1 − x)K 0.5Na 0.5NbO 3– xBi 0.8La 0.2FeO 3 [(1 − x)KNN– xBLF, 0.005 ≤ x ≤ 0.04] were synthesized by conventional solid-state sintering. Crystal structures and microstructures of the ceramics were characterized by X-ray diffraction and transmission electron microscopy. X-ray diffraction substantiates the existence of an orthorhombic-tetragonal morphotropic phase boundary (MPB) near x = 0.01. Highest electrical performances were observed near the MPB. The maximum remnant polarization, piezoelectric coefficient, and coupling factor were measured as 22.5 μC/cm 2, 144 pC/N, and 0.34, respectively. The effects of BLF on structures and electrical properties were discussed. Our results might be helpful for developing KNN-based piezoelectric ceramics.