Wide phase boundary zone, piezoelectric properties, and stability in 0.97(K0.4Na0.6)(Nb1−xSbx)O3–0.03Bi0.5Li0.5ZrO3 lead-free ceramics

Abstract

In this work, the rhombohedral (R) and tetragonal (T) phase boundary of the 0.97(K_0.4Na_0.6)(Nb_1−xSb_x)O₃–0.03Bi_0.5Li_0.5ZrO₃ piezoceramics has been attained in a wide composition range of 0.035 ≤ x ≤ 0.08, and the Sb⁵⁺ could simultaneously shrink its T_R–O and T_O–T. A giant d₃₃ of 380–405 pC N⁻¹ and a T_C of 200–292 °C have been observed in the ceramics with the coexistence of both R and T phases. In addition, the ceramics with 0.035 ≤ x ≤ 0.08 also show a good thermal stability of the d₃₃, and an enhanced temperature stability of ferroelectricity could be observed in the ceramic with x = 0.035. As a result, adding the optimum antimony content is an efficient way to promote the electrical properties of potassium–sodium niobate ceramics with the R–T phase boundary.