Dysprosium halides

Holmium is obtained from monazite, bastnasite and other rare-earth minerals as a by-product during recovery of dysprosium, thulium and other rare-earth metals. The recovery steps in production of all lanthanide elements are very similar. These involve breaking up ores by treatment with hot concentrated sulfuric acid or by caustic fusion separation of rare-earths by ion-exchange processes conversion to halide salts and reduction of the hahde(s) to metal (See Dysprosium, Gadolinium and Erbium). 

SC 600 models. Custom-made walk-in units with the metal halide option are also available. The lamp used is a Thorium doped Dysprosium lamp capable of illuminating large areas. 

Figure 32 shows the Rumed Model 1501 chamber (35). Rumed offers their models 1001, 1101, and 1401 models with either a 3500 K, 4500 K, or 6500 K metal halide lamp option. These lamps are available at two intensity levels, 18 and 40klux. The lamps appear, by their published spectral power distribution to be of the Thorium doped Dysprosium class. 

Halides of the lanthanides in the oxidation state -1-2 have been known since the early decades of the twentieth century. EuCl2, SmCl2, and YbCb were the first to be reported. For these 3 elements, ah 12 possible halides are known. This is not the case for the elements thulium, dysprosium, and neodymium for which only the halides of the fiiad chlorine, bromine, and iodine have been synthesized and crystallographically characterized. They structmaUy bear close resemblance to the respective alkahne-earth metal halides. The electronic configmations of the M + ions of these six elements are 6s 5d 4f with n = 4 (Nd), 6 (Sm), 7 (Eu), 10 (Dy), 13 (Tm), and 14 (Yb). 

Formation of such complex compoimds, but already with alkali-metal halides, has foimd application in the manufacture of modern metal halide lamps (Bom et al., 2004 Hilpert and Niemann, 1997), which have an emission spectmm close to that of the natural sunlight. Relevant iodides and bromides (particularly cerium and dysprosium bromides and iodides) were foimd to be the most suitable components of binary compoimds for the production of lamp vessels from silica glass (Markus et al., 2005). Further technological developments led to the replacement of vessel material by polycrystalline alumina and to the use of rare-earth chlorides for improving lamp characteristics (Rutkowska et al., 2004). 

---