From the CRC handbook of Chemistry and Physics, CRC Press, Cleveland, 55th ed., 1974-75 "The Elements" by C.R. Hammond. page B-12
DYSPROSIUM (Gr. dysprositos, hard to get at), Dy; at. wt. 162.50; at. no. 66; m.p. 1412 C; b.p. 2562 C; sp. gr. 8.550 (25 C); valence 3. Dysprosium was discovered in 1886 by Lecoq de Boisbaudran, but not isolated. Neither the oxide nor the metal was available in relatively pure form until the deve1opment ion-exchange separation and metallographic riduction techniques by Spedding and associates about l950. Dysprosium occurs along with other so-called rare-earth or lanthanide elements ina variety of minerals, such as xenotime, fergusonite, gadolinite, euxenite, polycrase, and blomstrandine. The most important sources, however, are from monazite and bastnasite. Dysprosium can be prepared by reduction of the trifluoride with calcium. The element has a metallic, bright silver luster. lt is relatively stable in air at room temperature, and is readily attacked and dissolved, with the evolution of hydrogen, by dilute and concentrated mineral acids. The metal is soft enough to be cut with a knife and can be machined without sparking if overheating is avoided. Small amounts of impurities can greatly affect its physical properties. While dysprosium has not yet found many applications, its thermal neutron absorption cross-section and high melting point suggest metallurgical uses in nuclear control applications for alloying with special stainless steels. A dysprosium oxide-nickel cemret has found use in cooling nuclear reactor control rods. This cermet absorbs neutrons readily without swelling or contracting under prolonged neutron bombardment. In combination with vanadium and other rare earths, dysprosium has been used in making laser materials. Dysprosium-cadmium calcogenides, as sources of infrared radiation, have been used for studying chemical reactions. .The cost of dysprosium metal has dropped in recent years since the development of ion- exehange and solvent extraction techniques, and the discovery of large ore bodies. The metal is still expensive, however, and costs about 70 cents/gm. or $190/lb. in purities of 99+%.
