Sm₂Fe₁₇N_xの磁気特性と窒化過程(集約)

抄録

Magnetic properties and nitrogenation mechanism of Sm₂Fe₁₇N_x(0 _??_ x _??_ 6) are discussed in this review.
The Sm₂Fe₁₇N_x specimens with 0 _??_ x _??_ 6 can be prepared by nitrogenating Sm₂Fe₁₇ in a mixed-gas atmosphere of NH₃ and H₂. Both saturation magnetization and anisotropy field reach the maximum values at x=3.0 (4πIs=15.7kG=1.57T, H_a=260kOe=21MA/m). We have already attained to fabricate high performance powder compressed magnet with (BH)_max of 21 MGOe (170kJ/m³).
A linear relation between a thickness of nitrogenated layer and time of nitrogenation can be seen in a reaction using a mixed gas of NH₃ and H₂. This fact suggests that the rate of the nitrogenating reaction using a mixed-gas of NH₃ and H₂ is dominated by interface-reaction process.
The difference of nitrogenating mechanism between (NH₃-H₂)-nitrogenation and N₂-nitrogenation is also discussed.