Preparation of Nd-Fe-B based magnetic materials by soft chemistry and reduction-diffusion process

Starting from superfine precursors, Nd-Fe-B based magnetic materials, Nd2Fe14B and Nd2Fe12Co2B, have been prepared by reduction-diffusion reaction at relative low temperature. The boride precursors used in the reactions, i.e., Co2.0B1.2 and Fe1.0B0.25, were obtained from the reduction of CoCl2 and FeSO4 with NaBH4 in aqueous solution at room temperature. The other precursors, Nd2O3 and Fe2O3 were obtained by a polymer network gel process. The obtained Nd2Fe14B and Nd2Fe12Co2B materials are line crystalline powders which show quite strong magnetic anisotropy. The particle sizes of these materials can be controlled to about a few microns without using mechanical milling processes.