Electrode connection optimization for both temperature difference and purification of lanthanum rod during solid-state electrotransport

In order to solve the problem of large temperature difference between the center and ends of the metallic rod in the purification process of solid-state electrotransport (SSE), three types of electrode connections of tantalum and the corresponding rods of metallic lanthanum were designed, the temperature distributions of three kinds of rod were measured, and the influence of temperature difference on the purification effect of solid-state electrotransport was investigated. The results indicate that the maximum temperature difference of the rod will be significantly reduced through decreasing the cross section of electrode connection to make its unit length resistance close to that of rod, or increasing the unit length resistance of the section at both ends of the rod. When these two measures are adopted at the same time, the effect of decreasing rod temperature difference is the best in the present study, and the maximum temperature difference of the rod can be reduced to 29 °C when the maximum temperature of the rod is 820 °C. The migration velocity of the impurities at rod ends can be obviously improved after the rod temperature difference is reduced, which enables the purification effect and efficiency of solid-state electrotransport to be greatly raised; it is also found that the major impurities iron in metallic lanthanum migrates more easily than oxygen and carbon during the purification of metal lanthanum with solid-state electrotransport.