Nanoparticle Approach to the Formation of Sm₂Fe₁₇N₃ Hard Magnetic Particles

Synthesis of mesoscopic particles of multi-component rare earth permanent magnet compounds

“…The temperature rate was kept as low as 2°C min –1 to avoid homogeneous nucleation of particulate Sm–O NPs. The method has been successfully extended to synthesize Fe 3 O 4 @Sm–O NPs, as shown in Figure 5(b ) [ 72 ]. The molar ratio of Fe to Sm could be tuned by adjusting relative amounts of Sm(acac) 3 and Co or Fe 3 O 4 NPs.…”

“…Copyright 2020 Wiley VCH. (b) Reproduced with permission from [ 72 ]. Copyright 2020 the Chemical Society of Japan …”

“…1.3 Fe 3 O 4 @Sm–O NPs ca . 30 1000 900 900(435 ③ ) 1.9 ±1.0 – – – – 1.3 [ 72 ] SmFe–O NPs 110 ±20 185 N/A 850(600 ② ) 0.10 ±0.02 – 127.9 – – 1.54 [ 74 ] [Fe–O,Sm–O] NPs – N/A 800 900(420 ② ) 0.47 ±0.09 – 132 – 89 2.47 ④ [ 95 ] 700 900(420 ② ) 0.6 ±0.2 – 134 – 100 2.28 ④ 950(420 ② ) 0.9 ±0.3 – 142 – 110 1.81 ④ 600 900(420 ② ) 0.6 – – – – ...…”

“…The Sm 2 Fe 17 N 3 phase is metastable and, thus synthesized by nitridation of the Sm 2 Fe 17 with N 2 or NH 3 in gas-solid reaction or with melamine (C 3 H 6 N 6 ) in a solid-state reaction under high temperature and/or pressure conditions. In practice [ 72 ], the Fe 3 O 4 @Sm–O NPs ( ca . 30 nm) described in Section 2 ( Figure 5(b )) were calcined at 1000°C for 1 h in air ( Figure 8(a,b,g(i)) ), and subsequently reduced by H 2 at 900°C for 1 h ( Figure 8(c,d,g (ii))).…”

“…Inset in (e) shows the grain size distribution of the Sm 2 Fe 17 N 3 MMPs. Reproduced with permission from [ 72 ]. Copyright 2020 the Chemical Society of Japan…”