Nickel Ferrite Thick Films Deposited by Vacuum-Arc Discharge

Abstract

Stoichiometric nickel ferrite films 10∼100 µ thick have been prepared by an arc evaporation in a vacuum of 10 -4 torr of the material sintered with the starting mixture (Ni0) 0.62 (Fe 2 O 3 ) 0.38 , and subsequent heat treatment in air at 1250∼1350°C. They have a saturation magnetization value σ s of 51 gauss·cm 3 /g agreed with the value for the bulk nickel ferrite. Their X-ray diffraction patterns and Mössbauer absorption spectra indicate that they may be composed of the polycrystalline particles with a homogeneous ion distribution and an inversed spinel structure. However, the as-deposited film is composed of the spinel, rock-salt and nickel types of small crystalline particles and the fine amorphous particles, and has σ s of 17 gauss·cm 3 /g. Since each component ion is distributed inhomogeneously in the particles, the heat treatment below 1200°C oxidizes them in different ways. Consequently, the structure and σ s of the film has a complex dependence on the heating temperature.