High-purity enrichment of 84Sr

High-purity 84Sr (i.e., >99 at%) is an important tool in many areas of basic and applied research, in particular for spikes used in isotopic dilution/mass spectrometer investigations in geochemistry, cosmochemistry, and paleoclimate-age studies. In nature, the 84Sr abundance is only 0.56%; however, it can be enriched to the specified requirements by using a high-resolution separator, such as the 180°-sector separator, or by completing two passes through a high-production, lower-resolution machine, such as the calutron. The latter option was used for this enrichment to produce ∼1 g of strontium with a final 84Sr concentration of 99.64%. Three innage runs were made, vaporizing a total of ∼17 g of metal feed that had been pre-enriched in the calutron to ∼70% 84Sr. A partial recovery, followed by recycle of the unresolved feed, was made after the second innage run. A process efficiency of 8.44% was achieved, and 4.33 g of the unresolved feed material was recovered. A modified ion-source unit using materials compatible with strontium and the use of krypton as mass markers to aid in operations are described. Standard contamination analyses were performed to evaluate the enrichment and to compare measured results with predicted product purity.