In situ formation of sol-gel derived PbTiO₃/NiFe₂O₄ biphase thin film

In this article, magnetoelectric (ME) biphase composite thin films consisted of PbTiO₃ as ferroelectric phase and NiFe₂O₄ as ferromagnetic phase which were successfully formed in situ by sol-gel process. The phase structure, morphology and dielectric properties of the films were measured by X-ray diffraction (XRD), scanning electron microscope (SEM) and LCR precision impedance analyzer. It is concluded that the thin films were capable of being controlled to form the biphase composite of PbTiO₃ and NiFe₂O₄ at the heat-treatment temperature between 600 and 850 °C. The phases coexisting in the composite thin film are in forms of solid solutions doped with Ni²⁺ and Fe³⁺ and with Ti⁴⁺, respectively. Their lattice constants vary with their doping contents. The capacitance of the composite thin film depends on the content of perovskite phase and the doping addition of Ni²⁺ and Fe³⁺ in crystalline phase of PbTiO₃.