Study on optimizing ultrasonic irradiation period for thick polycrystalline PZT film by hydrothermal method

► 9.2-μm-thick PZT polycrystalline film was obtained with a single deposition process. ► We verified that there is an optimum ultrasonic irradiation period for obtaining a thick film. ► We clarified that ultrasonic irradiation promotes the nucleation process in the hydrothermal method. ► We also clarified ultrasonic irradiation is almost ineffective in the crystal growth process.