Abstract: Two kinds of precursors, being transparency and milky in status respectively, were prepared. Thin films of Pb_0.9La_0.15TiO₃ were coated on glass
substrates with the two precursors added with or without crystallite nano powders of Pb_0.9La_0.15TiO₃ respectively by dip-coating methods. Scanning
electron microscopy (SEM), X-ray diffraction (XRD) and dielectric spectroscopy were respectively used to observe the morphology, phase status and dielectric
constant of the films. In conclusion, the initial temperature of forming the perovskite phase of Pb_0.9La_0.15TiO₃ thin film derived from the
milky precursor is 40-50℃ lower than that from transparency precursor. On the other hand, crystal lattice of the perovskite phase of the film derived
from the transparency precursor decreases while the calcination temperature is in high level of about 550℃ and up. The Curie point is near room temperature
when the film is calcined at about 525℃. And the solid solubility of La in the perovskite phase decreases with increasing the calcination temperature of the film, and vice versa.

Key words: PLT thin film, sol-gel, calcination temperature, phase formation