Highly (1 1 1)-oriented and pyrochlore-free PMN–PT thin films derived from a modified sol–gel process

Ferroelectric PMN–PT (68/32) thin films, about 250 nm in thickness, have been successfully grown on Pt/Ti/SiO2/Si substrate by a modified sol–gel process. Pure perovskite phase with highly (1 1 1)-preferred orientation, determined by X-ray diffraction, was formed in the PMN–PT thin films when annealed at 650 °C. The pyrochlore phase has been effectively avoided through a variation of the processing parameters such as Mg content, Mg precursor and annealing temperature during thin film deposition. FE-SEM investigation showed that the films have a smooth and crack-free surface with densely packed grains after annealed at 650 °C. The annealed films exhibited well-defined hysteresis loops, with a respective remanent polarization Pr of 16.1 μC/cm2 and coercive field Ec of 71.2 kV/cm at an applied electric field of 400 kV/cm at room temperature.