Effects of MnO2 addition on the microstructure and piezoelectric properties in Pb(Yb1/2Nb1/2)O3 -PbTiO3 ceramics near MPB

The variation of microstructure and piezoelectric properties of the Pb(Yb_1/2Nb_1/2)O₃-PbTiO₃ the (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≈0.5) which separates the pseudocubic and the tetragonal phase regions. For the 0.8 wt.% 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 (≈5 μm 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