For our requirement four different groups of materials: Amorphous, nanocrystalline, ferrites and iron-nickel alloys:

Amorphous cores are mainly available as toroidal cores. However, U-cores and blocks are available as well. Nanocrystalline cores are toroid cores. The core is usually epoxy coated or placed in a plastic enclosure. Ferrites are the most popular material due to relatively low costs and losses. Ferrite cores are available in many shapes.

Iron-nickel alloys are subdivided into two categories: Low nickel content alloys (50-60% Ni) with high saturation flux density and high nickel content alloys (80% Ni) with high permeability. Iron-nickel alloys are sensitive to mechanical stress; therefore, cores are placed in plastic enclosures.

• it is illustrated how the different material varies in terms of relative permeability vs. saturation flux density.

•Material with high relative permeability and high saturation flux density reduces the EMI inductor size as it allows for lower turns and thus directly reduces copper losses and capacitance.
Nanocrystalline and Fe-based amorphous materials have the highest saturation flux density, followed by iron-nickel alloys, Co-based amorphous and finally ferrites

•Magnetic materials with stable permeability characteristic are desired for the EMI filter as it drives energy storage capability.

•An Ni-Zn ferrite core has a stable permeability characteristic and is almost constant up to 500 kHz. An Ni-Zn ferrite has a very high resistivity. The core loss is driven by hysteresis losses as the eddy current effects are very low. Therefore, Ni-Zn ferrites are commonly used for MHz range applications.

1. High saturation flux.

2. High resistivity as eddy-current losses is inversely proportional to the electrical resistivity

3. Constant permeability characteristic with frequency and temperature