Effects of MnO doping on properties of 0.97K0.5Na0.5NbO3–0.03(Bi0.5K0.5)TiO3 piezoelectric ceramics

MnO-doped 0.97K0.5Na0.5NbO3–0.03(Bi0.5K0.5)TiO3 lead-free piezoelectric ceramics have been fabricated by solid state reaction. The MnO-doped KNN-BKT samples show tetragonal perovskite structure and the grain size increases obviously. With an addition of the optimal doping of MnO, all the electrical properties of the samples, especially the piezoelectric and pyroelectric performance, have been enhanced significantly. The KNN-BKT ceramics, with 0.8 wt% MnO doping, exhibits optimal electrical properties: d33 = 221 pC/N, kp = 44.7%, tgδ = 1.4%, ɛr = 1229, Qm = 143, ρ = 4.464 g/cm3 and p = 221 μC/m2 K.

Research highlightsLead-free piezoelectric KNN-BKT + xMnO ceramics have been synthesized by solid state reaction. The effect of MnO content on the piezoelectric, dielectric, ferroelectric and pyroelectric properties of the KNN-BKT ceramics has been studied. With the addition of MnO, the piezoelectric, dielectric and pyroelectric properties have been enhanced greatly with MnO doping. The KNN-BKT + xMnO ceramic with x = 0.8 exhibits the optimal properties: d33 = 221 pC/N, kp = 44.7%, tgδ = 1.4%, ɛr = 1229, QM = 143, ρ = 4.464 g/cm3 and p = 221 μC/m2 K.