The dependence of α-Fe particle size on the formation of Fe
16N
2 with giant magnetization was studied by nitriding α-Fe fine particles below 200°C with different particle size (60nm, 120nm, 300nm) derived from α-Fe
2O
3. Nitridation of the largest α-Fe particle (300nm) was difficult to obtain Fe
16N
2. Mixtures of Fe
16N
2 with unreacted α-Fe and Fe
4N were obtained by nitridation of the smaller α-Fe particles (120nm, 60nm). The nitridation process was most controllable for α-Fe particle of 120nm to obtain the most amount of Fe
16N
2. Magnetization was not enhanced by the formation of Fe
16N
2 probably due to disordering of the nitrogen introduced into Fe lattice. Monodispersed α-Fe particles could be obtained by thermal decomposition of Fe(CO)
5 in octylether. Their size could be controlled with the amount of added stabilizer in the ether. They could be nitrided to Fe
16N
2 in low temperature nitridation.
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