Improved temperature stability and high piezoelectricity in lead-free barium titanate-based ceramics

To achieve high piezoelectricity and the corresponding good temperature stability of BaTiO3 (BT) ceramics, a new system of (1-x-y) BaTiO3 - yCaTiO3 - x(BaZr1-zHfz)O3 (BT-yCT-xBZHz) was designed. The O-T phase boundary was observed at 0.065 ≤ x ≤ 0.085, 0.08 ≤ y ≤ 0.12 and 0 ≤ z ≤ 1.0 near room temperature. Due to the O-T phase boundary, the enhancement of electrical properties (d33 = 500 pC/N, kp = 0.52, Pr = 14.0 μC/cm2 and εr = 2800), large strain (∼0.23%) and d33* = 1100 pm/V (10 kV/cm) can be obtained. Moreover, temperature-dependent electrical properties were investigated in detail, and a reliable performance was realized due to high TC (>100 °C). The d33* was demonstrated to be temperature-insensitive from 16 °C to 60 °C (varying less than 7%), which is superior to the reported BT-based ceramics. Besides, d33 and Pr fluctuate less than 22% in this temperature range, also showing an usable stability. We believe that this work can be beneficial to facilitate an increasing adoption of lead-free BT-based piezoceramics for practical applications.