Preparation and characterization of self-assembled percolative BaTiO(3)–CoFe(2)O(4) nanocomposites via magnetron co-sputtering

BaTiO(3)–CoFe(2)O(4) composite films were prepared on (100) SrTiO(3) substrates by using a radio-frequency magnetron co-sputtering method at 750 °C. These films contained highly (001)-oriented crystalline phases of perovskite BaTiO(3) and spinel CoFe(2)O(4), which can form a self-assembled nanostructure with BaTiO(3) well-dispersed into CoFe(2)O(4) under optimized sputtering conditions. A prominent dielectric percolation behavior was observed in the self-assembled nanocomposite. Compared with pure BaTiO(3) films sputtered under similar conditions, the nanocomposite film showed higher dielectric constants and lower dielectric losses together with a dramatically suppressed frequency dispersion. This dielectric percolation phenomenon can be explained by the ‘micro-capacitor’ model, which was supported by measurement results of the electric polarization and leakage current.