Magnetic nanocomposites consist of nanoscale magnetic crystallites in an amorphous or crystalline matrix (e.g. polymers or silicates). Both soft and hard magnetic nanomaterials can be obtained. Soft magnetic materials are suitable for transformers and inductors in electronic components, whereas hard magnetic materials possess application potentials in energy storage, data memories and sensor technology. With nanostructured materials, physical parameters such as resistivity or coercivity can be adjusted selectively, which opens up new applications.
Inductive components are extensively used in high frecuency (> 1 MHz) electronic devices from radar, satellite, telecommunication systems to home radio stereos. Conventional inductive components use metallic alloys and ferrites as core materials. The major problem for metallic materials is their low resistivity. Since it is impossible to dramatically increase their resistivity, metallic materials were excluded in high frequency applications and ferrites have been the only choice for five decades. Although efforts have been made extensively to improve the performance of the ferrites, very limited progress was obtained. Magnetic materials have been a key impediment for the miniaturization of electronic equipment.
Nanocomposite processing has provided a new approach for fabricating soft magnetic materials. In a magnetic/ceramic or magnetic/polymeric nanocomposite, the resistivity can be drastically increased, leading to significantly reduced eddy current loss. In adidition, the exchange coupling between neighboring magnetic nanoparticles can overcome the anisotropy and demagnetizing effect, resulting in much better soft magnetic properties than conventional bulk from materials.
