An approach to further improve piezoelectric properties of (K _0.5Na_0.5)NbO₃-based lead-free ceramics

An approach to further improve piezoelectric properties of (1-x) (K0.5 Na0.5) Nb O3 -xLiNb O3 (KNLN) ceramics, i.e., the optimum poling temperatures (Tp) of KNLN ceramics should be chosen near the polymorphic phase transition temperatures, is proposed. This is contrary to conventional wisdom associated with electrical poling of ceramics. Piezoelectric constant d33 of KNLN (x=0.07) ceramics increases from 210 to 274 pCN by selecting optimum Tp. This result indicates that this approach is very effective in improving piezoelectric properties of KNLN ceramics. Moreover, this approach can also be applied to other (K0.5 Na0.5) Nb O3 based ceramics.