Effects of MnO2 addition on the microstructure and piezoelectric properties in Pb(Yb1/2Nb1/2)O-3-PbTiO3 ceramics near MPB

The variation of microstructure and piezoelectric properties of the Pb(Yb1/2Nb1/2)O-3-PbTiO3 (PYN-PT) solid solution system on addition of MnO2 has been investigated. Based on previous works, we have found that the PYN-PT solid solution has a potential for piezoelectric applications owing to its low-temperature sinterability and varieties of dielectric properties displayed by the changing composition. The MnO2 addition has caused an improvement in density and piezoelectric properties of the ceramics near the morphotropic phase boundary (x approximate to 0.5) which separates the pseudocubic and the tetragonal phase regions. For the 0.8wt.%MnO2-doped 0.52PYN-0.48PT ceramics, electromechanical coupling factors, both k(p) and k(t) are found to be 0.41 and 0.34, respectively. Mechanical quality factor (Q(m)) is more markedly increased from 79 to 812 with the 0.8wt.%MnO2 addition. We can obtain a dense ceramic body which has a uniform grain size (approximate to 5 mu m for y = 0.8) by an optimum doping of MnO2. Thus, we conclude that MnO2 might also be an effective dopant for the microstructure and piezoelectric property control of the PYN-PT ceramic system.