Phase transition and electrical properties of Bi0.5(Na0.8K0.2)0.5ZrO3 modified (K0.52Na0.48)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

Abstract

In this work, (1−x)(K0.52Na0.48)Nb0.95Sb0.05O3−xBi0.5(Na0.8K0.2)0.5ZrO3 [abbreviated as (1−x)KNNS−xBNKZ, x=0–0.06] lead-free ceramics were fabricated using solid-state reaction method. The effects of BNKZ contents on the phase structure, piezoelectric and ferroelectric properties were investigated. The phase boundaries including orthorhombic-tetragonal (O-T) and rhombohedral-tetragonal (R-T) multiphase coexistence were identified by XRD patterns and temperature-dependent dielectric constant by adding different content of BNKZ. A giant field induced strain (~0.25%) along with converse piezoelectric coefficient d33* (~629.4pm/V) and enhanced ferroelectricity Pr (~38μC/cm2) were obtained when x=0.02, while the specimen with x=0.03 presented the optimal piezoelectric coefficient d33 of 215pC/N, due to the O-T or R-T phase coexistence near room temperature respectively. These results show that the introduction of Bi0.5(Na0.8K0.2)0.5ZrO3 is a very effective way to improve the electrical properties of (K0.52Na0.48)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics.