Enhanced electrical properties and good thermal stability in K0.48Na0.52NbO3–LiNbO3–BiAlO3 lead-free piezoceramics

Abstract

Intense research on phase boundaries has led to the development of KNN-based ceramics with excellent properties. In this work, we reported enhanced electrical properties and high Curie temperature in (0.995−x)K0.48Na0.52NbO3−xLiNbO3−0.005BiAlO3 piezoceramics using the conventional solid-state sintering method. Phase evolution and electrical properties were investigated, which suggested the enhanced electrical properties were mainly ascribed to the existence of orthorhombic-tetragonal (O-T) phase boundary because of the polymorphic phase transition (PPT). For example, optimized electrical properties of d 33 ~ 287 pC/N, k p ~ 47%, d 31 ~ 84.3 pC/N, g 31 ~ 11.98 × 10−3 Vm/N, tan δ ~ 2.6%, and T C ~ 447 °C were observed for the ceramics with x = 0.045. Additionally, a good thermal stability of piezoelectricity (e.g., d 33 ≥ 235 pC/N, T ≤ 400 °C) was also observed by thermal depoling method. As a result, we believe this material system with a good comprehensive performance will promote the development of KNN-based ceramics and make them used in practical applications.