Solid state electrotransport

D. Electrorefining, Zone Melting, and Solid-State Electrotransport... 

Ultrapure Th metal has been processed at the Ames Laboratory by solid-state electrotransport under very low pressures (on the order of 0.3 nPa), which has produced the purest Th metal known, that with a resistivity ratio of 4200 for doubly refined metal (99-101). This resistivity ratio of 4200 translates into probably <50 ppm total impurities in the metal (see footnote 1) (87-90, 104). Single crystals measuring 0.25 cm in diameter by 1.1 cm in length with resistivity ratios of 1700-1800 have also been grown (55). 

Secondary refining processes such as zone melting and solid-state electrotransport (Section III,D) should yield ultrahigh-purity Pa metal. 

If the actinide metal is available in sufficient quantity to form a rod or an electrode, very efficient methods become applicable eiectrorefining, zone melting, solid state electrotransport. Thorium, uranium and plutonium have been refined by electrolysis in molten salts An electrode of impure metal is dissolved anodically in a molten salt bath, e.g. in LiCl-KCl eutectic the purified metal is deposited on the cathode as a solid or a liquid. 

The method of solid state electrotransport has produced rare earth metals of higher purity than any other method. The principle of purifying metals by... 

The author wishes to thank Professor O.V. Lounasmaa for his guidance and assistance in collecting and assessing the materials required. She further wishes to thank Professor R.W. Hill and Drs. R.G. Jordon and P.C. Lanchester for their kindness in sending her their unpublished results, along with appropriate comments, on solid-state electrotransport purified samples of the heavy lanthanides. Finally, the Department of Solid State Physics of the University of Uppsala and that of the Technical University of Stockholm are to be thanked for their hospitality and provision of working space during the preparation of this chapter. 

Refinement and crystal growth by solid state electrotransport. 

The author wishes to thank Dr. D. Fort for reading the manuscript and for allowing access to his review of solid state electrotransport prior to publication, and to Mr. S.D. Sutton for his help with compiling the references. 

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