Ferroelectric PbTiO₃ Powders and Thin Films Derived from Sol‐Gel Processing

Abstract

Abstract Lead titanate powders and thin films were prepared by the sol‐gel process of metal alkoxide solutions and solvents. From DSC measurements, phase transition temperature of crystallized PbTiO 3 powders was obtained at about 484 °C. From XRD investigation, it was confirmed that the tetragonal phase of polycrystalline PbTiO 3 thin films is formed by coating of concentrated solution on all of the substrates we used after heat treatment above 500 °C. It was found by SEM and ellipsometric analysis that the thin film coated with 0.25 M concentrated solutions once had an average thickness of about 720 Å. Surfaces of thin films were crack‐free, uniform, and its average grain size investigated by SEM was 0.6–0.8 μm. Band gap energy of PbTiO 3 thin film coated on the Al 2 O 3 (2243) substrate was 3.45 eV, which is assumed to be due to the direct band to band transition. Dielectric constant (ϵ) and dielectric loss (tan δ) of PbTiO 3 thin film amounted to 60–70 and 0.01–0.02 in the region of 10 kHz ∼ 1 MHz at room temperature, respectively, and transition temperature was 486 °C at 1 MHz. From the hysteresis loop of PbTiO 3 thin film, spontaneous polarization of 12 μC/cm 2 and coercive filed of 45 kV/cm were obtained.