Effects of particle size on the phase transition in Pb(Zr, Ti)O-3 grown by the sol-gel technique

The variation of the tetragonal distortion (c/a) with particle size of Pb(Zr, Ti)O3 nanoparticle thin films prepared by the sol-gel technique is reported. The tetragonal distortion of the unit cell, which is related to the spontaneous polarization, decreases exponentially with size and vanishes at 16 nm. This distortion was correlated with the used additive in the preparation processing and crystallization temperature of the films, and the existence of a critical grain size for the ferroelectric phase transition was observed. The phase transition was monitored by X-ray diffraction, scanning electron microscopy, and electrical measurements.