Research Progress of Purification of Rare Earth Metals by Solid-State Electrotransport in China and Overseas

Abstract

High purity rare earth metals and their materials are widely used in magnetic, optical, catalytic, hydrogen storage, superconducting, nuclear energy, electronic information and other fields, which are the key core materials for the research and development of high-tech materials. Solid state electrotransport (SSE) is an important method to prepare rare earth metals with absolute purity above 99.99%, containing gas impurities, which can not only effectively remove most of metal impurities such as Al, Cu, Fe, Co, Ni, et al, but also be able to remove trace interstitial impurities, such as C, N, O, et al, generally difficult to be removed by other purification methods. The development of SSE purification of rare earth metal, including SSE purification theory, equipment and purification process, five criteria for impurity migration direction and their advantages and disadvantages, influence of temperature and external field on impurity migration rate, diffusion coefficient, migration direction and impurity removal difficulty, influence of different measures on purification efficiency and how to obtain higher purity metal, are comprehensively expounded. Finally, future development direction of SSE purification of rare earth metal is prospected.