Role of A- and B-site excess doping on the improvement of the piezoelectric properties of BaTiO3 lead-free piezoceramics

Abstract

Excess Li, Al, and Si co-doped BaTiO3 (BT) piezoceramics were synthesized using a conventional solid-state reaction sintering method. The influences of excess A- and B-site doping on the crystalline structure, dielectric, ferroelectric, and piezoelectric properties of BT ceramics were studied and discussed. While ceramics had a tetragonal crystal structure, weak secondary phases appeared with an increase in the doping content. Compared to pure BT ceramics, the dielectric constant of the Li/Al/Si-doped ceramics decreased, but the dielectric loss decreased and remained at a relatively low level of approximately 0.017 with a Li–Al content of x and 0.02 with an excess Si doping content of Δ. The remnant polarization 2Pr reached the maximum values of 12.55 μC/cm2 at x = 0.07 for excess Li–Al doped ceramics and 18.58 μC/cm2 at Δ = 1.6% for excess Si doped ceramics. The piezoelectric constant d33 was significantly improved owing to the excess doping of Li–Al and Si without decreasing the Curie temperature, and its maximum value was approximately 212 pC/N at x = 0.032. The excess Si doping at the B-site helped to improve and stabilize the piezoelectric properties of the ceramics in a wide excess composition range.