Effect of niobium/manganese addition on the piezoelectric properties and the electric-field-induced strains in PZT

The effects of MnO2 addition on the piezoelectric properties of Nb2O5-doped Pb(Zr-0.53 Ti-0.47)O-3 (PZT) ceramics are investigated. When Nb2O5 is dope d to PZT, the planar coupling coefficient (K-P) significantly increases, bu t the mechanical quality factor (Q(M)), as well as the electrical quality f actor (Q(E)), decreases. When MnO2 and Nb2O5 are co-doped, Q(M) increases r emarkably while K-P changes only slightly. This increase of Q(M) is ascribe d to the domain pinning by Mn as in the previously reported case of MnO2-do ped PZT. Meanwhile, little change in K-P is ascribed to the rarely changed tetragonality. Even though MnO2-Nb2O5 co-doped PZT shows smaller induced st rain than does Nb2O5-doped PZT, excellent temperature stability is obtained . It is shown that MnO2-Nb2O5 co-doped PZT is suitable for high-power piezo electric actuator applications because of its high K-P, Q(M), and Q(E), its low dielectric constant, and its excellent temperature stability.