JSI - Synthesis of Materials K8

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Head of Department 

Prof. Dr. Darko Makovec
darko.makovec@ijs.si 
Telephone: +386 1 477 35 79

 

 

Secretary

Bernarda An┼żelak
bernarda.anzelak@ijs.si
Telephone: +386 1 477 33 23

 

Magnetic materials for high-frequency application    

 

The frequency range of electromagnetic equipment is shifting towards higher frequencies for two reasons. First, the miniaturization of the equipment and, second, the exploitation of the unused frequency range above 30 GHz. At the same time, the widespread application of high-frequency equipment is the reason for electromagnetic interferences and electromagnetic pollution. Therefore, the materials that efficiently absorb high-frequency electromagnetic radiation are required for the protection of devices, workplaces and humans.

Hexaferrites are materials exhibiting suitable magnetic properties for the preparation of passive components and electromagnetic absorbers for applications up to 90 GHz. Their useful properties at such high frequencies are the result of the anisotropy in the crystal and magnetic structures.

High-frequency magnetic components based on hexaferrites are usually in the form of bulk ceramics. But for frequencies above 30 GHz, thick films are more suitable. Regardless of the shape, the material has to be magnetically oriented. Hexagonal plates of the material are oriented in a plane to which the easy axis of magnetization is perpendicular. Such a configuration enables the operation of hexaferrites without any external magnetic field, because the layers of ceramics are in the remanent state.

Influence of the orientation of haxaferrite grains on the magnetic hysteresis loop (left) of ideally oriented material (centre) and the example of a preferentially oriented layer of BaFe12O19 particles (scanning electron microscope image of the surface - right).

JSI - Synthesis of Materials K8