Phase transition and electrical properties of Bi0.5(Na0.8K0.2)0.5ZrPO3 modified (K0.52Na0.48)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

In this work, (1 - x)(K0.52Na0.48)Nb0.95Sb0.05O3 - xBi(0.5)(Na0.8K0.2)(0.5)ZrO3 [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 (0-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 (similar to 0.25%) along with converse piezoelectric coefficient d(33)* (similar to 629.4 pm/V) and enhanced ferroelectricity P-r (similar to 38 mu C/cm(2)) were obtained when x=0.02, while the specimen with x=0.03 presented the optimal piezoelectric coefficient d(33) of 215 pC/N, due to the O-T or R-T phase coexistence near room temperature respectively. These results show that the introduction of Bi-0.5(Na0.8K0.2)(0.5)ZrO3 is a very effective way to improve the electrical properties of (K0.52Na0.48)(Nb0.95Sb0.05)O-3 lead-free piezoelectric ceramics. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.