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

The effects of manganese addition on the piezoelectric properties, microstr ucture, sintering characteristic and Curie temperature have been studied fo r Pb(Zr,Ti)O-3 (PZT) ceramics. The valence states of manganese are measured by Electron Spin Resonance (ESR). Those studies show that manganese coexis t mainly in the way of Mn2+ and Mn3+ in PZT ceramics. When the concentratio n of Mn ion is below 0.5 mole%, it is preferentially incorporated in the la ttice 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 wi ll be incorporated in the lattice of (Ti, Zr) site in Mn3+ acted as accepto r, which increases Q(m) without causing large changes of K-p and d(33). Whe n 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 prop erties of PZT ceramics. Small amount of Fe may decrease the solubility limi t of Mn ion in PZT ceramics and it may also prevent the oxidation of Mn2+ a nd Mn3+. (C) 2000 Kluwer Academic Publishers.