Synthesis of Fe3O4/FeO/CoNi composite material and study of its magnetic properties

Fe3O4/FeO/CoNi composite materials were produced using a two-step process. In the first step, oxide precursor was produced at low temperature by wet-synthesis based Pechini method. In the second step, the precursor was heated to 500, 600, 700 or 800 oC under reducing hydrogen gas and metal/oxide composite material was obtained. The structural, morphological and magnetic properties of materials produced at different temperatures were investigated using X-ray diffraction, scanning electron microscope and vibrating sample magnetometer. Sudden changes in magnetic properties were observed during transition from 600 oC to 700 oC. The saturation magnetization doubled while coercive force was halved. These changes were explained with the crystallization of magnetic CoNi phase from an amorphous state and nearly doubling of particle size of Fe3O4 phase.

Fe3O4/FeO/CoNi kompozit malzemenin sentezi ve manyetik özelliklerinin incelenmesi

Fe3O4/FeO/CoNi kompozit malzemesi iki aþamalý proses kullanýlarak üretildi. Birinci aþamada, oksit prekürsörü (öncül malzeme) ýslak sentez esaslý Pechini yöntemi kullanýlarak düþük sýcaklýkta üretildi. Ýkinci aþamada prekürsör malzemesi 500, 600, 700 veya 800 oC’ye hidrojen gazý altýnda ýsýtýlarak indirgendi ve metal/oksit kompozit malzemesi elde edildi. Farklý sýcaklýklarda üretilen malzemelerin yapýsal, morfolojik ve manyetik özellikleri X-ýþýný kýrýnýmý, tarama elektron mikroskobu ve titreþen örnek manyetometresi kullanýlarak incelendi. 600 oC’den 700 oC’ye geçiþte manyetik özelliklerde ani deðiþiklikler gözlendi. Doygunluk mýknatýslanmasý iki katýna çýkarken, koersif kuvvet yarýya indi. Bu deðiþiklikler manyetik CoNi fazýn amorf bir yapýdan kristal bir yapýya geçiþiyle ve Fe3O4 fazýn parçacýk boyutunun yaklaþýk olarak iki katýna artmasýyla açýklandý.