Preparation and magnetic properties of Fe_100-xNi_x-SiO₂ granular alloy solid using a sol-gel method

The preparation of Fe_100-xNi_x-SiO₂ (x = 0, 20, 60, 80) granular solid using a sol-gel method is investigated by means of X-ray diffraction and electron transmission micrography. Pure Fe metal, Fe₄₀Ni₆₀ and Fe₂₀Ni₈₀ ultrafine alloy particles dispersed in Fe-SiO₂, Fe₄₀Ni₆₀-SiO₂ and Fe₂₀Ni₈₀-SiO₂ granular solid have been fabricated which are confirmed by the result of the XRD and the Mössbauer spectrums. The evolution of the magnetic properties for the Fe₄₀Ni₆₀-SiO₂ and Fe₂₀Ni₈₀-SiO₂ granular solid during reducing are described in detail and explained by using superparamagnetism, single-domain and multidomain theory.