New lead-free piezoelectric ceramics based on (K0.48Na0.52)(Nb0.95Ta0.05)O3–Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3

Abstract

(1 − x)(K_0.48Na_0.52)(Nb_0.95Ta_0.05)O₃–xBi_0.5(Na_0.7K_0.2Li_0.1)_0.5ZrO₃ lead-free piezoelectric ceramics with a new type of phase boundary have been designed and fabricated. This phase boundary lies in the compositional range of 0.04 ≤ x ≤ 0.05, and is formed by the coexistence of the rhombohedral, orthorhombic, and tetragonal phases. Interestingly, we found that the ferroelectric, dielectric, and piezoelectric properties of the ceramics with compositions near the phase boundary are significantly enhanced. In particular, the ceramic with x = 0.045 shows the best piezoelectric behavior of d₃₃ ∼ 290 pC/N and k_p ∼ 0.42 among all the compositions studied in this work, and it also exhibits a good thermal stability at annealing temperatures of ≤270 °C. All these results indicate that such a material system is a good candidate for lead-free piezoelectric applications in the future.