Defect‐driven evolution of piezoelectric and ferroelectric properties in CuSb ₂ O ₆ ‐doped K _0.5 Na _0.5 NbO ₃ lead‐free ceramics

Abstract

Abstract Defect greatly affects the microscopic structure and electrical properties of perovskite piezoelectric ceramics, but the microscopic mechanism of defect‐driven macroscopic properties in the materials is not still completely comprehended. In this work, K 0.5 Na 0.5 NbO 3 + x mol CuSb 2 O 6 lead‐free piezoelectric ceramics were fabricated by a solid‐state reaction method and the defect‐driven evolution of piezoelectric and ferroelectric properties was studied. The addition of CuSb 2 O 6 induces the formation of dimeric (DC1) and trimeric (DC2) defect dipoles. At low doping concentration of CuSb 2 O 6 (0.5‐1.0 mol%), DC1 and DC2 coexist in the ceramics and harden the ceramics, inducing a constricted double P‐E loop and high Q m of 895 at x =0.01. However, DC2 becomes more dominant in the ceramics with high concentration of CuSb 2 O 6 (≥1.5 mol%) and thus leads to softening behavior of piezoelectricity and ferroelectricity as compared to the ceramic with x =0.01, giving a single slanted P‐E loop and relatively low Q m of 206 at x =0.025. All ceramics exhibit relatively high d 33 of 106‐126 pC/N. Our study shows that the piezoelectricity and ferroelectricity of K 0.5 Na 0.5 NbO 3 ceramics can be tailored by controlling defect structure of the materials.