Chemical synthesis and coercivity enhancement of Nd2Fe14B nanostructures mediated by non-magnetic la

• 作 者: Kai Zhu Junjie Xu Xiaobai Wang Wei Li Kesong Tian Yanglong Hou
• 机 构: Beijing Key Laboratory for Magnetoelectric Materials and Devices(BKLMMD), Beijing Innovation Centre
• 出 处: 纳米研究（英文版）
• 发表日期: 2020年4期
• 关键词: Nd2Fe14B nanostructures chemical reduction diffusion process grain boundary grap

High-performance Nd2Fe14B magnets have been widely required in various fields recently due to the lightweight and miniaturization of devices.In this work,we synthesize Nd2Fe14B nanostructures with tunable magnetic properties through surfactant-assisted high energy ball milling (SAHEBM) process,achieving prominently enhanced coercivity by forming non-magnetic layers as grain boundary phase.When the reduction annealing process was carried out as pellet with Ca,the coercivity increased from 0.8 kOe to over 3 kOe as Nd2Fe14B powder,which is proved to be the contribution of the chemical diffusion of Nd elements and the formation of Nd-rich layer as magnetic insulating medium.In addition,two-dimensional graphene oxide (GO) was employed to build extra grain boundary,by which the coercivity of the core@dual-shell structure can achieve up to 8 kOe,tenfold of the original sample.The intrinsic mechanism indicated that the Nd-diffusion induced Nd-rich phase along with the reduced GO in the system could form non-magnetic layer as grain boundary and magnetically isolate the adjacent grains,significantly enhancing the exchange coupling effect.This work markedly opens up an effective approach for the chemical preparation of high-performance Nd2Fe14B nanostructured magnets,especially after post treatment,and gives an insight on the interactions at nanoscale.