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

Article abstract of DOI:10.1016/S0925-8388(96)02741-7

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., Co_2.0B_1.2 and Fe_1.0B_0.25, 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 fine 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.