Studies On Preparation And Properties Of BaTiO₃/γ-Fe₂O₃Composite Films

Multiferroic materials mean this materials simultaneously exhibit two or more ferroelectricity. ferromagnetism and ferroelaticity. In this materials, an external electric field can induce magnetization, an external magnetic field can induce polarization, there exits magnetoelectric coupling effect. Those peculiar magnetoelectric coupling properties give more freedoms for materials and multifunctional devices, which lead to the potential applications in data-read-and-write device, microcircuit, sensor and spintronics. The research of multiferroic materials have drawn more attention because of their rich new physics and their potential applications.In this paper. BaTiO3/γ-Fe2O3composite films are deposited on Si substrates by RF magnetron sputtering method. The ferroelectric properties, dielectric properties and ferromagnetic properties of BaTiO3/γ-Fe2O3composite films are discussed. The main works are listed as following:(1) BaTiO3/γ-Fe2O3composite films are deposited by RF magnetron sputtering method. Then composite films are annealed at different temperature in high vacuum environment.(2) BaTiO3/γ-Fe2O3; composite films’crystal structure are investigated by X-ray diffraction. The results indicate that BaTiO3/γ-Fe2O3composite films are crystallized after annealing. The SEM result indicates that BaTiO3/γ-Fe2O3composite films after700℃annealing is crystallized with a dense and uniform surface. The EDX results indicate that there are no other impurities in composite films, the proportion of each atom in BaTiO3/γ-Fe2O3composite films are agree with the proportion of the target. (3) BaTiO3/γ-Fe2O3composite films’ dielectric after annealing are investigated by Agilent4294A precision impendance analyzer and electrochemical analyzer. The results indicate that the leakage current of BaTiO3/γ-Fe2O3composite films after annealing meet the test requirements; the measured relative permittivity shows no remarkable frequency dependence; the relative permittivity of BaTiO3/y-Fe2O3composite films after annealing are increased as the of annealing temperature increases;(4) Ferroelectric hysteresis of BaTiO3/y-Fe2O3composite films are investigated by precision multiferroic precision materials analyzer. The results indicate that all BaTiO3/γ-Fe2O3composite films show the ferroelectric and composite films afer annealing above500℃have better ferroelectric hysteresis. The remanent polarization Pr and coercive field Ec of BaTiO3/γ-Fe2O3composite films after annealing are increased as the of annealing temperature increases.(5) Magnetic hysteresis loop of BaTiO3/γ-Fe2O3composite films are investigated by vibrating-sample-magnetometer (VSM). The results indicate that all BaTiO3/γ-Fe2O3composite films show the ferromagnetic and the saturation magnetization of BaTiO3/γ-Fe2O3composite films after annealing are decreased as the of annealing temperature increases.