Effect of Co2O3 Additive on Structure and Electrical Properties of 85(Bi1/2Na1/2)TiO3-12(Bi1/2K1/2)TiO3-3BaTiO3 Lead-Free Piezoceramics

In this paper, Co2O3-added-85(Bi1/2Na1/2)TiO3-12(Bi1/2K1/2)TiO3-3BaTiO(3) (BNKB) lead-free piezoceramics were fabricated by the conventional solid oxide routine. By the use of X-ray photonic spectra, X-ray diffraction, and scanning electronic microscope, the valence state of Co cations, lattice distortion, and microstructures were investigated. It is revealed that the Co2O3 addition affects the concentration of Co3+ cations and changes the tetragonality c/a of the perovskite lattice. The variation in tetragonality and microstructure, combined with the acceptor doping behavior of Co2O3, play a determinant role in the depolarization temperature T-d, mechanical quality factor Q(m), and other electrical properties of the ceramics. The T-d is elevated to 157 degrees C for 0.5 mol% Co2O3 addition; and the Q(m) reaches a maximum of 626 at 1.5 mol% Co2O3 addition, which is in the highest flight compared with other BNKB ceramics reported until now.