Perovskite crystallization kinetics and dielectric properties of the PMN-PT films prepared by polymer-modified sol-gel processing

Pb(Mg_1/3,Nb_2/3)O₃-PbTiO₃ (PMN-PT, 43% PT) thin films have been developed by modified sol-gel processing with polyvinylpyrrolidone (PVP) as a modifier and lead nitrate as a lead source. With PVP modification, perovskite phase was directly crystallized from amorphous film matrix at a temperature as low as 430 °C, and the crystallinity was significantly enhanced. Kinetics studies show that the crystallization process is controlled by heat transfer phenomena at the annealing temperatures ≤460 °C. At higher annealing temperatures (550–700 °C), it is a diffusion-controlled reaction with an activation energy of 167.7 kJ/mol, almost two times lower than that for the films without PVP modification. The promotion mechanism of perovskite crystallization by PVP addition has been discussed accordingly. The resultant films consisted of nanocrystallines and exhibited relaxor-like dielectric behavior, although the composition of the films located in normal ferroelectrics.