Application of reduction-distillation method for preparing high-purity rare-earth isotope metals

Abstract

Reduction-distillation techniques were developed at Oak Ridge National Laboratory to provide high-purity rare-earth metal isotopes in a chemical and physical form compatible with cold-rolling of ultrathin foils. The method involves high-temperature reduction of rare-earth oxides, using a suitable metal reductant, with simultaneous distillation of the product metal from the reaction matrix. Metal condensates at a purity level of 99.95% (500 ppm total impurity) can be obtained, and the ductility of rare-earth metals at this purity permits ultrathin foils (0.00005 to 0.00002-in. thickness) to be prepared. Collection efficiencies of between 75 and 92% are achieved even when only 15 mg of the element (in oxide form) is processed by the reduction-distillation method, which makes it highly valuable and effective in obtaining most of the rare-earth isotopes in elemental form. Foils cold-rolled from these pure materials are applicable for use in precision nuclear cross-section measurements and in solid-state physics experiments.