Magnetization of cadmium ferrite prepared by coprecipitation

We investigated the magnetization of the ultrafine cadmium ferrite particles formed during the coprecipitation method and discussed the origin of enhanced magnetization based on the magnetic properties. A transmission electron microscopy micrograph shows aggregation of fine particles having two kinds of shapes, fibrous and granular. X-ray diffraction patterns of the specimens prepared by the coprecipitation method are composed of peaks corresponding to CdFe₂O₄, Cd(OH)₂, and α-FeO(OH). The pattern indicates that the peaks of CdFe₂O₄ are fairly broad, suggesting the formation of a very small crystallite, with an average size of ∼8 nm. The ultrafine CdFe₂O₄ particles exhibit ferromagnetic behavior and have a net magnetization of 89±5 emu/g at 6 K. These results suggest that there must be many ferromagnetic clusters consisting of Fe³⁺ ions at the B sites around Fe³⁺ ions at the A site by the A-B interactions. Thus, such a change in the distribution of Fe³⁺ ions in the ultrafine CdFe₂O₄ particles results in increasing magnetization with decreasing particle size.