Preparation of Fe4N from Nd-containing precursors

Abstract Iron nitride powders, with composition Fe 4 N, have been prepared from Nd-containing precursors using pure ammonia (NH 3 ) gas. The precursors were a mixture of iron oxide and neodymium hydroxide made by coprecipitation of metal salts (FeCl 3 ) and Nd(NO 3 ) 3 ·6H 2 O) with sodium hydroxide (NaOH) in aqueous solution. The presence of Nd 3+ ions in the system promoted the formation of Fe 4 N. The as-made sample has a saturation magnetization of 150 emu/g (200 emu/g if only the mass of the iron nitride is included). The high magnetization is due to the protection of the particle surface by the neodymium oxide.