Piezoelectric and dielectric properties of Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3–Ba0.77Ca0.23TiO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (1 − x)Bi0.5(Na0.84K0.16)0.5TiO3–xBa0.77Ca0.23TiO3 (BNKT–xBCT, x = 0–0.04) were synthesized by conventional solid-state reaction method. The piezoelectric, dielectric, and ferroelectric characteristics of the ceramics are investigated and discussed. The XRD results show that Ba0.77Ca0.23TiO3 (BCT) has diffused into Bi0.5(Na0.84K0.16)0.5TiO3 (BNKT) lattices to form a new solid solution. It is shown that moderate additive of BCT (x ≤ 0.025) in BNKT–xBCT ceramics can enhance their piezoelectric and ferroelectric properties. Three dielectric anomalies are observed in BNKT–xBCT (x ≤ 0.03) ceramics. The piezoelectric measurements and P–E hysteresis loops reveal that BNKT–0.025BCT ceramic has the highest piezoelectric performance and strongest ferroelectricity in all the samples. Piezoelectric constants d 33, k p, and k t of 175 pC/N, 29.1, and 54% are, respectively, achieved. Remnant polarization P r and coercive field E c reach 28.3 μC/cm2 and 24.2 kV/cm, respectively.