Microstructure and electrical properties of (1 − x)K0.5Na0.5NbO3–x(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free piezoelectric ceramics

Abstract

The (1 − x)K0.5Na0.5NbO3 − x(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (KNN–BCTZ) lead-free ceramics were fabricated by conventional solid-state sintering technique. The microstructure and electrical properties of the ceramics were investigated. The X-ray diffraction analysis revealed that the ceramics formed a single phase perovskite solid solutions with the symmetry of orthorhombic at x 0.04. The coexistence of orthorhombic and pseudocubic (tetragonal) phases was observed near room temperature when 0.03 ≤ x ≤ 0.04. The grains grew up obviously when 2 mol% BCTZ was added, but the grain size was found to reduce gradually with further increasing BCTZ content. The T C and T O-T decreased with the increasing BCTZ content. The ferroelectric and piezoelectric properties were abruptly degraded as x ≥ 0.05. Optimum properties (d 33 = 136 pC/N, k p = 27 %, k t = 26.5 %, Q m = 25, P r = 14.67 μC/cm2, E c = 11.23 kV/cm, T C = 347 °C, \(\varepsilon_{33}^{\text{T}} /\varepsilon_{0} = 8 6 1. 5\), tan δ = 0.04) were obtained for the ceramica with x = 0.03.