Method for the fabrication of thick multilayered nickel/iron oxide nanoparticle magnetic nanocomposites

Abstract Magnetic nanocomposites consisting of ferrite nanoparticles and magnetic metals have been of interest for use in power electronic components due to their ability to achieve relatively high magnetic permeabilities while also having low losses. Unfortunately, fabrication challenges limit the maximum achievable thickness of these films to ∼4 µm, though thicker films are desirable for increased power handling. To overcome these challenges this works seeks to demonstrate a fabrication method whereby thick composite films can be made by constructing sequential composite layers, performing electrophoretic deposition and electro-infiltration steps for each layer. Composite samples of iron oxide nanoparticles electro-infiltrated with nickel that are 1, 3, 5, 7, and 10 layers thick will be fabricated and characterized both structurally and magnetically. Structural measurements accomplished with SEM show that each layer appears to contribute 4 µm to the total thickness, with the one layer sample being 3.99 ± 0.12 µm thick and the ten layer sample being 39.19 ± 3.1 µm thick. Results show that the dc magnetic properties of these composites stay constant as thickness increases, having an average magnetic saturation of 464 kA/m, and coercivity of 2.5 kA/m. The ac magnetic properties similarly showed that the permeability of the composites also stayed consistent at 20. However, the dimensional resonance frequency of the composites decreased as thickness increased, lowering to ∼96 MHz for 1 layer (∼4 µm) to ∼8 MHz for 10 layers (∼40 µm), revealing a trade-off between thickness of a maximum operating frequency.