Temperature-insensitive electrical performance of the potassium sodium niobate-based ceramics modified by barium zirconate

A series of barium zirconate modified potassium sodium niobate-based lead-free piezoelectric ceramics [(0.97-x)(K0.45Na0.55)(Nb0.97Sb0.03)O-3-0.03Bi(0.5)K(0.075)Na(0.425)ZrO(3)-xBaZrO(3), KNNS-BKNZ-xBZ, x=0 similar to 0.02] were prepared by the traditional solid-state method. The effect of BZ on the phase structure and electrical properties was systematically studied. Rhombohedral-orthorhombic-tetragonal multiphase coexistence structure can be observed for the whole ceramic system while the addition of BZ leads to the reduction in the orthorhombic phase content and increase in the rhombohedral and tetragonal phase content. At the critical composition with x=0.01, the ceramics show the optimized electrical properties with the piezoelectric constant d(33) of 265 pC/N, unipolar strain S-uni of 0.168%, inverse piezoelectric coefficient d(33)* of 480 pm/V, room-temperature dielectric constant epsilon(r) of 1634, and Curie temperature T-C of 282 degrees C. Moreover, enhanced temperature stability was achieved in the x=0.01 ceramics, presenting the variation of d(33) less than 15% within the temperature range of 20-100 degrees C and the S-uni remained above 80% until the elevated temperature of 175 degrees C.