High-performance Nd2Fei4B magnets have been widely required in various fields recently due to the lightweight and miniaturization of devices.In this work,we synthesize Nd2Fei4B nanostructures with tunable magnetic pro...High-performance Nd2Fei4B magnets have been widely required in various fields recently due to the lightweight and miniaturization of devices.In this work,we synthesize Nd2Fei4B 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 Nd2Fei4B 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.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.51590882,51631001,51672010),and the National Key R&D Program of China(No.2017YFA0206301).
文摘High-performance Nd2Fei4B magnets have been widely required in various fields recently due to the lightweight and miniaturization of devices.In this work,we synthesize Nd2Fei4B 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 Nd2Fei4B 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.
