Chemical Synthesis of Magnetically Hard and Strong Rare Earth Metal Based Nanomagnets

Abstract

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Modelling of phase stability: integrating computational materials science and materials informatics

“…In this review, we provide an overview of modeling studies of phase stability in alloys, including theories, models and methods. The Sm-Co alloy system, as one of the two most famous rare-earth permanent magnetic materials families [45] , is taken as an example, with the consideration that this system is rich in various stable and metastable phases under the conditions of binary compositions [46][47][48][49][50][51][52][53] . Efforts are made to introduce the progress in the studies of the phase stability and transformation behavior of Sm-Cobased alloys, in which the development of the research approaches from the traditional CMS methods to strategies based on the materials informatics is particularly demonstrated.…”

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

“…Unfortunately, the hightemperature annealing would lead to the aggregation and the diffusion between hard and soft phase [24,25]. Furthermore, the nanosized product is prone to oxidation for their high activity, which could lower their performance [26][27][28].…”

“…Furthermore, it can be seen that there are amorphous shells with a thickness of 1-3 nm on the surface of SmCo 5 particles, suggesting a possible oxidation phenomenon in the washing process, which results in a low M s in Fig. 3b (black loop) [26][27][28]. Figure 3e displays a TEM image of SmCo 5 /GN, in which 15-nm SmCo 5 particles with 1-2-nm graphene shells can be clearly observed.…”