The Ames Laboratory has been actively involved in the preparation
of very pure rare earth metals since the early 1940's when Dr.
Frank H. Spedding and his group of pioneers developed the ion-exchange
process, a technique that separates the "fraternal fifteen" plus
yttrium and scandium. As a result of this and subsequent work,
high-purity oxides are available from which high-purity rare earth
metals can
be prepared. In most cases, the rare earth oxides are first converted
to their respective fluorides and are then reduced metallothermically
on a kilogram scale, using pure calcium metal specially sublimed
for this purpose. The resulting metals are very pure. Nonetheless,
many are further refined at the MPC by one of the following processes:
Purification
Techniques
vacuum casting
sublimation
distillation
zone refining
electro-transport processing
Quantities of high-purity rare earth metals
and alloys in single and polycrystalline forms are available to
scientists outside
of Ames Laboratory. Complete chemical
analyses, obtained by laser mass spectrometry, inert gas fusion and combustion
analysis, accompany the materials. Special preparations of high-purity
alloys and compounds are also available in small quantities.