Microstructure and piezoelectric properties of Na0.5K0.5NbO3–BiNiO3–LiSbO3 lead-free ceramics

Lead-free (0.94 − x)Na0.5K0.5NbO3–xBiNiO3–0.06LiSbO3 piezoelectric ceramics have been sintered at 1105 °C by ordinary solid mixed oxide method. The phase transitional behavior and various electrical properties were investigated. All samples are typical ABO3 style perovskite structure. A morphotropic phase boundary between orthorhombic and tetragonal ferroelectric phases has been identified in the composition range of 0.002 ≤ x ≤ 0.004. Main piezoelectric parameters of these ceramics were optimized around x = 0.002 with an enhanced piezoelectric constant d33 of 240 pC N−1, a planar electromechanical coefficient kp of 44%, a mechanical factor Qm of 38, and a Curie temperature Tc of 360 °C. These results indicate the materials studied have a promising future in a wide range of applications.