Ferrite plating of Fe3O4 and Fe3-xNixO4 films at 100-200°C

Ferrite plating of Fe_3-xNi_xO₄ ( x=0-0.93) films in the temperature region T=120°C-200°C and in the pressure region P=15-20 kg/cm² was performed. A reaction solution and an oxidizing solution were supplied to a reaction cell by high-pressure pumps. A phase diagram for an iron oxide film was obtained for T=120°C-180°C and pH=4.0-7.6. Single-phase Fe₃ O₄ (x=0) film grows only at T=180°C and pH=6.0-7.6, with the α-Fe₂O₃ phase appearing outside the region. The solubility limit of Ni increases as the plating temperature increases, from x=~0.3 at 80°C to x=0.93 at 200°C. All the films are polycrystalline with no preferential orientation, and the magnetization exhibits no definite anisotropy. The grain size of the films increases as x increases, reaching ~1 μm at x=0.86