Large blocking force in Bi1/2Na1/2TiO3-based lead-free piezoceramics

Blocking stress (σb) and free strain (Sf) are the most important parameters for piezoelectric actuators, both having a decisive impact on the electromechanical performance. Here, we report on the blocking stress of lead-free piezoceramics, using 0.94Bi1/2Na1/2TiO3–0.06BaTiO3 (6BT) and 0.98(0.94Bi1/2Na1/2TiO3–0.06BaTiO3)–0.02K0.5Na0.5NbO3 (2KNN) as prototypical compositions. While 6BT delivers high σb = 102 MPa at 125 °C, the addition of 2 mol.% K0.5Na0.5NbO3 results in a large σb = 124 MPa at room temperature. Therefore, both lead-free materials outperform lead zirconate titanate at their respective peak temperatures.