Grain size effect on the phase transitions in oriented PbTiO_3 thin films deposited by the sol-gel method on (111) Pt/Si

摘要

Oreinted PbTiO_3 thin films with different average grain sizes were prepared by the sol-gel method on (111) Pt/Si substrates. The phase transitions in the films were investigated by using high-temperature XRD measurements. It was found that the phase transition from tetragonal to cubic in the film of grain size ～210 nm occurs at about 480 deg. C, whereas it occurs at around 460 deg. C in the film of grain size ～130 nm. The transition is reversible but with about 20 deg. C hysteresis between cooling and heating. The Curie temperature T_c measured for both films are lower than that of the bulk. cooling and heating. The Curie temperatures