Sintering behavior, phase structure and electric properties of KNNTS-BKNZ ceramics with excessive alkali metals

Abstract

We investigated the effect of excessive alkali metals on sintering character, phase structure, dielectric, piezoelectric and ferroelectric properties in KNN-based ceramics thoroughly. The 0.96(K0.48Na0.52)1+xNb0.93Sb0.02Ta0.05O3–0.04Bi0.5(K0.12Na0.88)0.5ZrO3 [(KN)xNTS-BKNZ] lead-free piezoelectric ceramics were prepared by conventional solid-state reaction method. The sintering temperature of (KN)xNTS-BKNZ ceramics increases gradually while the sintering temperature zone becomes narrow with the increasing x value. For the composition of x > 0.03, the grains could not grow in all sintering temperature. The coexistence system of rhombohedral and tetragonal phases has been found in (KN)xNTS-BKNZ ceramics and the TR−T, TC, d33, and er show a upward tendency with the increasing x when 0 ≤ x ≤ 0.03. The maximal piezoelectric coefficient d33 of 415 pC/N was obtained at x = 0.03. In addition, these ceramics presented good temperature stability. This study exhibits that excessive alkali metals influence sintering character and electrical properties on KNN ceramics deeply. It was believed that this work would be helpful for further understanding the effect of excessive alkali metals on sintering behavior and electric properties in KNN-based ceramics.