Magnetite/maghemite mixture prepared in benzyl alcohol for the preparation of α″-Fe16N2 with α-Fe

Fine powder of iron oxide has been required in the preparation of ferromagnetic α″-Fe16N2 powder in low temperature nitridation. Magnetite and maghemite mixture was obtained by the reaction of iron acetylacetonate Fe(acac)3 in benzyl alcohol. It was reduced to α-Fe in hydrogen at 400 °C. Particle size of the α-Fe was 300 nm in the reduction of iron oxides obtained from 2 g of Fe(acac)3. It decreased to 100 nm in the preparation using 8 g of Fe(acac)3. After the successive nitridation under ammonia flow at 160 °C, the highest yield of α″-Fe16N2 in 66 wt.% was observed on the nitrided product from the latter α-Fe, because of the smallest α-Fe particle size after the reduction in the present study. The yield and reproducibility of α″-Fe16N2 formation in low temperature nitridation was improved using the iron oxide prepared in non-aqueous benzyl alcohol compared to the use of magnetite obtained from aqueous solution.