Structural and electrical properties of Zr-doped K0.48Na0.52NbO3 ceramics: “Hard” lead-free piezoelectric

Abstract

The structural and electrical properties of K_0.48Na_0.52Nb_1−xZr_xO_3−δ (x = 0–0.04) ceramics prepared by the conventional solid-state reaction method were studied. Pellets with composition x ≤ 0.03 sintered at 1125 °C for 2 h showed single-phase of potassium sodium niobate (KNN) perovskite structure. Based on X-ray diffraction and Raman results, a mixture of orthorhombic and monoclinic phases was observed in intermediate compositions. The addition of Zr improved the sinterability and the “hard” piezoelectric properties of KNN, increasing the E_c and Q_m values. The composition with x = 0.03 presented the highest permittivity at room temperature, ɛ_r′ = 363 and the lowest dielectric losses, tan δ = 0.027. Moreover, it was the sample with the highest Q_m and d₃₃ values, with Q_m = 1781 and d₃₃ = 82 pC/N. It was therefore the best compositions to obtain a “hard” piezoelectric material based on Zr-doped KNN, which makes it promising candidate for use as “hard” lead-free piezoelectric material for high power applications.