Ge-doped magnetite thin films with an enhanced resistance to oxidation

Abstract The ability of metal-doped magnetite (Fe3O4) thin films to resist oxidation during annealing in air was investigated. The films were prepared on glass substrates by radio-frequency sputtering using a target of metal chips set on a ceramic Fe3O4 disk. The metal elements used in this study were Ge, Mo, W, and Mg. The films were annealed at different temperatures in air and the activation energy of oxidation was estimated. The Ge-doped film was high stable against oxidation with an activation energy of 490 KJ/mol, which was 2.5 times larger than that of undoped film. Elemental mapping using energy dispersive X-ray microscopy (EDX) and selected area electron diffraction (SAED) revealed that the Ge-doped Fe3O4 film was composed of a heterostructure that consisted of α-Fe2O3 and Fe3O4 containing small amount of Ge.