Structure and magnetic properties of cobalt ferrite foam with low mass density

It is extremely desirable but challenging to develop a facile synthesis to directly prepare permanent magnet foam with high coercivity ( H c ) and low mass density to meet the requirements of advanced magnets in modern industry. In this work, we developed a facile strategy to synthesize cobalt ferrite foam by solution combustion method and subsequently annealing treatment. The structure and magnetic properties of the foams can be influenced by the ratios of glycine to nitrate (G/N), Co content and annealing treatment temperatures. The increase in the mean grain sizes within the single domain range gives rise to an enhancement in coercivities. The highest H c of ∼3 kOe with an ultra-low mass density of ∼45 mg/cm 3 can be successfully obtained by controlling the preparation process. The work opens up a new way to prepare ultra-light Fe-based oxides for magnetic and catalytic applications.