Growth of highly textured PbTiO₃ films on conductive substrate under hydrothermal conditions

Perovskite structure (ABO₃) thin films have wide applications in electronic devices due to their unique properties, including high dielectric permittivity, ferroelectricity and piezoelectric coupling. Here, we report an approach to grow highly textured thick lead titanate (PbTiO₃) films on conductive substrates by a two-step hydrothermal reaction. Initially, vertically aligned TiO₂ nanowire arrays are grown on fluorine-doped tin oxide (FTO) coated glass, which act as template crystals for conversion to the perovskite structure. The PbTiO₃ films are then converted from TiO₂ NW arrays by diffusing Pb²⁺ ions into the template through a second hydrothermal reaction. The dielectric permittivity and piezoelectric coupling coefficient (d₃₃) of the PbTiO₃ films are as high as 795 at 1 kHz and 52 pm V^-1, respectively. The reported process can also potentially be expanded for the assembly of other complex perovskite ATiO₃ (A = Ba, Ca, Cd, etc) films by using the highly aligned TiO₂ NW arrays as templates. Therefore, the approach introduced here opens up a new door to synthesize ferroelectric thin films on conductive substrates for application in sensors, actuators, and ultrasonic transducers that are important in various industrial and scientific areas.