One-Pot Synthesis and Large-Scale Production Strategies for Preparing Ultrafine Hard Magnetic Sm₂Fe₁₇N₃ Nanoparticles

Abstract

In this study, we demonstrate a facile strategy for the large-scale preparation of ultrafine magnetic Sm 2 Fe 17 N 3 particles. During the preparation of magnetic nanoparticles (which includes reduction at a high temperature), a blocking agent (e.g., CaO), which enwraps the intermediate phase and discretizes it from the magnetic phase, is often introduced to control the particle size. Contemporary size-control strategies involve immersing solid Sm−Fe intermediates (e.g., Sm 2 O 3 −Fe mixed powder or SmFeO 3 ) in a liquid Ca-based precursor solution followed by a series of chemical reactions. However, a heterogeneous reaction with different phases (e.g., solid−liquid) leads to particulate aggregation, resulting in irregular shapes and broad size distribution of the magnetic particles and deteriorated magnetic performance. In this study, therefore, soluble Ca nitrates were added to Sm− and Fe−nitrate precursor solutions for controlling the size of Sm 2 Fe 17 N 3 submicron particles. Furthermore, the effect of such an addition on the microstructure and phase formation of the Sm−Fe binary system is elucidated. The resulting solutions were used as starting materials for the nitrate salt-based one-pot preparation process. The final products show a significant enhancement in magnetic performance (1.6 times higher energy product), indicating that the method has great potential for practical and inexpensive large-scale commercial applications.

Review—Chemical Structures and Stability of Carbon-doped Graphene Nanomaterials and the Growth Temperature of Carbon Nanomaterials Grown by Chemical Vapor Deposition for Electrochemical Catalysis Reactions

“…The coupling of inactive graphene material with active MoS 2 in a circuit element offers new avenues for improving energy device performance and circumventing existing restrictions. 28 Lee et al 29 described a chemical approach for making sizecontrolled SmCo 5 nanoparticles and covering them with a layer of N doped graphitic C to protect them from air oxidation (NGC). SmCo-O nanoparticles were painted with poly-dopamine and were annealed to generate SmCo-O/NGC nanoparticles.…”

Advanced Magnetic Actuation: Harnessing the Dynamics of Sm2Fe17–xCuxN3 Composites

“…The reduction–diffusion process, intended to produce Sm 2 Fe 17 N 3 in powder form without additional pulverization, inadvertently results in a nonuniform particle size distribution and size-dependent H ci issues due to the overgrowth of intermediates. To tackle these challenges, our study introduces Cu into the Sm 2 Fe 17 N 3 system, enhancing the material’s low-temperature magnetic properties and promoting a more uniform particle morphology. − This strategic modification not only leverages the inherent magnetic strengths of Sm 2 Fe 17 N 3 but also extends its utility in the realm of magnetic soft actuators, signifying substantial advancement in the application of hard magnetic materials.…”