Effects of addition of MnO on piezoelectric properties of lead zirconate titanate

The effects of manganese addition on the piezoelectric properties, microstructure, sintering characteristic and Curie temperature have been studied for Pb(Zr,Ti)O-3 (PZT) ceramics. The valence states of manganese are measured by Electron Spin Resonance (ESR). Those studies show that manganese coexist mainly in the way of Mn2+ and Mn3+ in PZT ceramics. When the concentration of Mn ion is below 0.5 mole%, it is preferentially incorporated in the lattice Pb site in Mn2+ or Mn3+, which gives rise to the increase of K-p and d(33). In the intermediate concentration region of 0.5-1.5 mole%, Mn ion will be incorporated in the lattice of (Ti, Zr) site in Mn3+ acted as acceptor, which increases Q(m) without causing large changes of K-p and d(33). When the concentration of Mn ion is larger than 1.5 mole%, it will accumulate at the grain boundaries and give rise to the decrease of piezoelectric properties of PZT ceramics. Small amount of Fe may decrease the solubility limit of Mn ion in PZT ceramics and it may also prevent the oxidation of Mn2+ and Mn3+. (C) 2000 Kluwer Academic Publishers.