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Exchange Hardened Ferrimagnetic Nanocomposites

Having significant role in the storing, delivering and conversion of the energy, the permanent magnets are key elements in the actual technology. In many applications, the gap between ferrites and rare earths (RE) based sintered permanent magnets is nowadays filled by RE bonded magnets, used in more applications, below their magnetic performances. Therewith, the recent trends in the RE market concerning their scarcity, impose EU to consider alternative magnets (without RE) to fill such gap. The paper presents the chemical synthesis of the exchange coupled SrO•6Fe2O3/CoO•Fe2O3 nanocomposites, based on nanoferrites. The appropriate annealing leads to the increasing of the main magnetic characteristics, saturation magnetisation MS and intrinsic coercivity Hc, in the range of 49 – 53 emu/g, respectively 126.5 – 306 kA/m (1589 - 3843 Oe). The value reached for the ratio between remanent magnetisation and saturation magnetisation is higher than 0.5, fact that proved that between the two magnetic phases occurred exchange interaction.

Author(s):

Mirela Maria CODESCU    
R&D National Institute for Electrical Engineering ICPE-CA Bucharest
Romania

Wilhelm KAPPEL    
R&D National Institute for Electrical Engineering ICPE-CA Bucharest
Romania

Elena CHITANU    
R&D National Institute for Electrical Engineering ICPE-CA Bucharest
Romania

Eugen MANTA    
R&D National Institute for Electrical Engineering ICPE-CA Bucharest
Romania