Large electro-strain signal of the BNT–BT–KNN lead-free piezoelectric ceramics with CuO doping

Abstract

This paper investigates a system of 0.93Bi0.5Na0.5TiO3–0.06BaTiO3–0.01K0.5Na0.5NbO3–xCuO (BNT–BT–KNN–xCuO, x=0−0.04mol.%) ceramics, which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier. The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics. With the doping of CuO, the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature, resulting in pinched P–E loops and “sprout” shape S–E curves. For the composition with x=0.01, a high unipolar strain of 0.39% under 5kV/mm contributes a large d33∗∼780pm/V at room temperature, which is competitive with the other BNT-based ceramics.

Keywords

• Lead-free piezoelectric ceramics
• BNT-based
• CuO dopant
• electro-strain