Effects of MnO/sub 2/ addition on the microstructure and piezoelectric properties in Pb(Yb/sub 1/2/Nb/sub 1/2/)O/sub 3/-PbTiO/sub 3/ ceramics near MPB

Abstract

The variation of microstructure and piezoelectric properties of the Pb(Yb/sub 1/2/Nb/sub 1/2/)O/sub 3/-PbTiO/sub 3/ the (PYN-PT) solid solution system on addition of MnO/sub 2/ 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 MnO/sub 2/ addition has caused an improvement in density and piezoelectric properties of the ceramics near the morphotropic phase boundary (x/spl ap/0.5) which separates the pseudocubic and the tetragonal phase regions. For the 0.8 wt.% MnO/sub 2/-doped 0.52PYN-0.48PT ceramics, electromechanical coupling factors, both k/sub p/ and k/sub t/ are found to be 0.41 and 0.34, respectively. Mechanical quality factor (Q/sub m/) is more markedly increased from 79 to 812 with the 0.8wt.%MnO/sub 2/ addition. We can obtain a dense ceramic body which has a uniform grain size (/spl ap/5 /spl mu/m for y=0.8) by an optimum doping of MnO/sub 2/. Thus, we conclude that MnO/sub 2/ might also be an effective dopant for the microstructure and piezoelectric property control of the PYN-PT ceramic system.