Synthesis of SmCo5 nanoparticles with small size and high performance by hydrogenation technique

Recent Research Trend in Powder Process Technology for High-Performance Rare-Earth Permanent Magnets

“…Recent research has demonstrated that micron-sized fine alloy powders can be directly synthesized by the R-D process from fine raw powders synthesized by a wet chemical method, and it has been reported that the powders synthesized by the R-D process exhibit higher coercivity than milled powders because the R-D powders are free of surface damage (Tada S. et al, 2012). Particularly, the last ten years of research have successfully shown that submicron-sized alloy powder can be synthesized by using of nano-sized oxide raw powders prepared by the pyrolysis or sol-gel method, and by using techniques to prevent necking and particle growth during Ca reduction (Ma Z.-H. et al, 2018;Zhang H. et al, 2011a). As mentioned above, the R-D method has high potential for producing fine rare earth magnetic powders and has been energetically studied, especially for Sm-Co and Sm-Fe-N alloys.…”

“…4 summarizes the particle size dependency of coercivity for SmCo 5 fine powders. (Dong Y. et al, 2019;Li C. et al, 2018;Ma Z.-H. et al, 2018;Ma Z. et al, 2019a;Ma Z. et al, 2019c;Ma Z. et al, 2015;Shen B. et al, 2019;Tang H. et al, 2020a;Tang H. et al, 2020c;Wu Q. et al, 2020b;Zhang H. et al, 2011a). Coercivity improves as the average particle diameter becomes finer, but reaches its maximum at about 400 nm and then decreases in the smaller diameter range.…”

“…Particle size dependency of coercivity of SmCo 5 powder (Dong Y. et al, 2019;Li C. et al, 2018;Ma Z.-H. et al, 2017;Ma Z. et al, 2019a;Ma Z. et al, 2019b;Ma Z. et al, 2015;Shen B. et al, 2019;Tang H. et al, 2020a;Tang H. et al, 2021;Tang H. et al, 2020b;Wu Q. et al, 2020a;Zhang H. et al, 2011b). Tang (2020b) Ma ( 2015) Ma ( 2017) Tang ( 2021) Shen ( 2019) Dong ( 2019) Ma (2019a) Li ( 2018) Wu ( 2020) Ma (2019b) Zhang ( 2011) Tang (2020a) are free of the particle surface contamination which is a drawback of the chemical synthesis processes described in Section 2.1.2.…”

Stabilizing Hard Magnetic SmCo5 Nanoparticles by N-Doped Graphitic Carbon Layer

“…Samarium cobalt (SmCo) alloys are a special class of rare earth metal (REM) magnetic materials that are important for magnetic and electronic applications in a broad temperature range. − Nanostructured SmCo, especially SmCo nanoparticles (NPs), may serve as magnetic building blocks for fabrication of permanent magnets with further enhanced magnetic performance. − With dimension-tunable magnetic properties, these SmCo NPs can be made with both large coercivity and high magnetic moment, making it possible to prepare nanocomposites with high energy products that are key to miniaturizing magnetic and electronic components. − There have been tremendous efforts devoted to preparing nanostructured SmCo or SmCo NPs via both physical and chemical processes. − A physical process is often considered a top-down approach in which a bulk material is fragmented into nanostructured features or thin films. , As a comparison, a solution phase chemical process is a conventional bottom-up approach and has the potential to control both NP dimension and dispersion, making it possible to assemble these NPs into high performance nanocomposite magnets. − However, chemicals involved in any of the solution processes do make the product purification challenging, which is further aggravated by easy oxidation of nanostructured SmCo alloys, degrading their magnetic performance. ,− …”

Stabilizing interface of SmCo5/Co nanocomposites by graphene shells

“…An alternative strategy to address these issues is the chemical synthesis, which mainly involves in the liquid solution synthesis of oxide precursor and reductive annealing by calcium [16][17][18][19][20][21][22][23]. Unfortunately, the hightemperature annealing would lead to the aggregation and the diffusion between hard and soft phase [24,25].…”