Berthollide ferrite films deposited by vacuum-arc evaporation

Non-stoichiometric magnetite films 5 μm thick have been prepared on alumina or glass substrates at temperatures in the range of C by a dc arc evaporation in a vacuum of about 10^-4Torr of the cathode at the high deposition rate of 5 × 10³Å/min. The source material used as the cathode was the bulk iron ferrite sintered in a nitrogen gas atmosphere with a starting mixture of wüstite and hematite (Fe0.91O)0.45(α-Fe2O3)0.55. The films have saturation magnetization per gram σsof 75 emu/g agreed with that of the powder of maghemite (γ-Fe2O3), squareness ratio of 0.45 and coercive force Hc of 730 Oe. Their X-ray diffraction patterns and Mössbauer absorption spectra indicated that they might be composed of the small polycrystalline particles of a Berthollide type of iron ferrite with the least amount of the very fine amorphous particles.