Formation of nano-Ag/BiFeO3 composite thin film with extraordinary high dielectric and effective ferromagnetic properties

The Ag/BiFeO3 composite thin films were prepared by sol–gel technology on ITO/glass substrate. Most of the Ag+ ions were reduced to form Ag nanoparticles in the thin film. Some Ag+ ions were doped into the BiFeO3 lattice to replace Bi, forming Ag doped BiFeO3. The average size of the Ag nanoparticles is 4–8 nm. The dielectric constant of the BiFeO3 thin film sintered at 550 °C with the molar ratio of Ag/Fe of 0.2 was enhanced to 139, which was nearly twice as high as that of pure BiFeO3. The dielectric loss kept at a low value of 0.15. The composite thin film also showed a typical ferromagnetism with the saturation magnetization of 2.2 emu/cm3. The Ag/BiFeO3 composite thin film showed typical ferromagnetism and high permittivity simultaneously.