Effect of Sintering Temperature on Structural and PiezoelectricProperties of PNN-PZT Ceramics

Sintering temperatures affect the structural and piezoelectric properties of PbNi1/3Nb2/3-PbZrO3-PbTiO3 system considerably; therefore the effect has been studied on mechano-chemicallyprocessed powder. This process involves activating mixed oxides of PbO, NiO, Nb2O5, ZrO2 andTiO2, and in the present study, calcination steps at an intermediate temperatures were skippedwhich are usually required in conventional solid state reaction methods and chemical routes.Single-phase formation was confirmed from XRD patterns which shows rhombohedral structureat higher sintering temperature. Investigations of the microstructure indicate almost linear increasein grain size from 0.98 m to 2.56  m when the sintering temperature was varied from 1050 oC to1150 °C. A high value of planar coupling factor (kp) = 67 per cent and piezoelectric charge coefficient(d 33 ~ 750 pm/V; (as determined from strain versus electric field curve at low field) were obtainedfor the ceramic specimens sintered at 1100 °C. The maximum strain was observed ~ 0.21 per centat 40 kV/cm applied field for the sample sintered at 1100 °C for 4 h.