What lets us separate the Praseodymium from the Neodymium (and from the other Rare Earths)?
Neodymium
Praseodymium Bear with us for a brief excursion into the arcanum of the atom. Consider the highly schematized d i a g r a m s of t h e t w o r a r e - e a r t h elements shown above. N o t e t h e electron shells labelled (in the convenient shorthand of the physicist) as 5s2, 5pc, 5do, and 6s2. These outermost or valence electron shells are exactly the same for both elements. So is it for all of the rare earths —more properly the lanthanides— from element 57 (lanthanum) to element 71 (lutetium). Within this group, as atomic number increases, electrons are added to t h e wellshielded if shell (the heavy lines in our diagrams). We have now shed some light on (1) why the rare earths exhibit such remarkably similar chemical properties, (2) why n a t u r a l minerals containing the rare earths usually contain all of them, plus thorium and the chemically similar yttrium, and (3) why classical methods such as fractional crystallization and precipitation are impractical for the
separation and purification of the rare earths. For all of their familial affinity, however, we of the Rare Earth Division are producing high-purity lanthanides and their compounds. In grams, pounds, and carload lots. T h e r e a s o n : We use t e c h n i q u e s such as ion-exchange and solvent extraction t h a t we have specifically developed for the separation and purification of the rare earths. We are able, for example, to produce the appreciable quantities of yttrium and europium needed for the manufacture of phosphors for color television and gaseous discharge lamps. The lanthanum used for petroleum-cracking catalysts. The cerium, yttrium, and lanthanum compounds used for ceramics and optics. The other high-purity rare-earth chemicals t h a t are the stuff of which state-of-the-art lasers, microwave devices, semiconductors, a n d s u p e r c o n d u c t o r s are m a d e . Tomorrow's demands for as-yetundisclosed kinds and quantities of
these chemicals will be similarly fulfilled by us. And we of the Rare Earth Division can provide a sometimes more valuable ingredient—our own hardwon experience. We can further help by putting at your fingertips the unusually large body of information pertinent to the rare earths. Two centuries have been spent by a host of investigators in puzzling over and pinning down many of the properties of these "new" materials. What is new about the rare earths is the way their singular characteristics (that Uf electron shell again) are the keys to many of the problems of basic and applied research. Your kind of problems. Can they be solved by one of the readily available, not-so-rare rare earths? Ask us. If you're interested in the rare earths and their compounds, it's easy to remember exactly who we are: RARE
EARTH
DIVISION,
American
Potash & Chemical Corporation, 258 Ann S t r e e t , West Chicago, Illinois 60185. Phone: 312 231-0760. 7-211
American Potash & Chemical Corporation
