Grain size dependence of high power piezoelectric characteristics in Nb doped lead zirconate titanate oxide ceramics

The grain size dependence of high power piezoelectric properties and their variation upon heat generation for Nb doped lead zirconate titanate oxide (PZT)-based ceramics were investigated under high AC electric fields. The temperature rise was found to decrease linearly upon reduction in grain size and was about 40% lower for fine grained ceramic (0.9 mum) compared to coarse grained one (3.0 mum) near the maximum vibration velocity level (0.30 m/s) whereas coercive field displayed a linear increase upon lowering the grain size. Furthermore, a rise in vibration velocity and mechanical quality factor (Q(m)) under low electric fields was found to correlate with decreasing grain size. Such a trend was explained in terms of the pinning effect of grain boundaries, which is observed to be critical for suppressing heat generation in high power ceramic applications.