Abstract: The structural, dielectric, ferroelectric and pyroelectric, properties of Pb(Zr_xTi_1－x)O₃ (PZT) ferroelectric thin films and their compositionally graded thin films on LaNiO₃/Si substrates were reported. Firstly, LaNiO₃ (LNO) thin films were prepared on Si(100) wafer by metalorganic decomposition (MOD) method. Then, Pb(Zr_xTi_1－x)O₃ ferroelectric thin films and their compositionally graded thin films were prepared on LaNiO₃/Si substrates by sol-gel method. The composition depth profile of a typical up-graded film was determined by using a combination of auger electron spectroscopy and Ar ion etching. The results confirm that the processing method produces graded composition change. XRD analysis shows that the graded thin films possess composite structure of tetragonal and rhombohedral. The dielectric constant of the graded thin films is higher than that of single-phase thin film, but dissipation factor is similar with each other at 10 kHz. The dielectric constants and dissipation factor for graded thin film annealed at 600 °C for 0.5 h are found to be 317 and 0.057 at 10 kHz, respectively. The hysteresis loops show that the remanent polarization of graded thin film is higher than that of single-phase thin film, but the coercive field is smaller than them. The remnant polarization (Pr) and coercive field (Ec) of the graded film are estimated to be 29.96 μC•cm^－2 and 54.12 kV•cm^－1, respectively. The pyroelectric coefficient of the graded thin film, which is 5.54×10^-8 C•cm^－2•K^－1 at room temperature, shows gradual increase with the temperature and is higher than that of single-phase thin film.

Key words: LaNiO₃ thin films, Compositionally graded thin films, Pb(Zr_xTi_1－x)O₃, Pyroelectric coefficient