Intrinsic Piezoelectricity In (K,Na)Nbo3-Based Lead-Free Single Crystal: Piezoelectric Anisotropy And Its Evolution With Temperature

Searching for lead-free piezoelectric materials with a large piezoelectricity and excellent thermal stability has been a major concern in both scientific research and practical applications. To understand the mechanism of high piezoelectricity and its temperature-dependent behavior in lead-free materials, we focus here on the tetragonal (K,Na,Li)(Nb,Ta)O-3 single crystal and investigate the intrinsicd33* along arbitrary directions as well as its evolution with temperature. The synergistic influence of several factors (narrow tetragonal temperature interval, sharp tetragonal-cubic phase transition, and large P-S below T-C) leads to a strong anisotropy in thed33* profile, while a highd33* is obtained around theta = 45 degrees over a wide temperature range. This work comprehensively reveals the physical mechanism of piezoelectric anisotropy in lead-free materials, which provides vital information to design high-performance lead-free piezoelectric materials through orientation engineering and lattice manipulation, which is expected to benefit a wide range of piezoelectric materials.