Praseodymium fluoride

Figure 2. Infrared spectra taken at 80°K. of praseodymium-fluoride...

The first step in obtaining praseodymium is to treat monazite, basmasite, or another ore to separate the lanthanoids from each other. The various elements are then changed to compounds of fluorine, such as praseodymium fluoride (Prp3). Praseodymium metal can then be obtained by passing an electric current through molten (melted) praseodymium fluoride ... 

PrF3 PRASEODYMIUM FLUORIDE 1323 RbCI[g] RUBIDIUM CHLORIDE (GAS) 1366... 

PrF3[g] PRASEODYMIUM FLUORIDE (GAS) 1324 Rb2CI2[g] DIRUBIDIUM DICHLORIDE (GAS) 1367... 

Ion-exchange and solvent extraction techniques have led to much easier isolation of the rare earths and the cost has dropped greatly in the past few years. Praseodymium can be prepared by several methods, such as by calcium reduction of the anhydrous chloride of fluoride. 

Bowlby BE, Di Bartolo B (2003) Spectroscopy of Trivalent Praseodymium in Barium Yttrium Fluoride 106 193-208... 

Neodymium, along with lanthanum, cerium and praseodymium, has low melting points and high boiling points. The fluorides of these and other rare earth metals are placed under highly purified helium or argon atmosphere in a platinum, tantalum or tungsten crucible in a furnace. They are heated under this inert atmosphere or under vacuum at 1000 to 1500°C with an alkali or alkaline earth metal. The halides are reduced to their metals ... 

Primary sources of the element are bastnasite and monazite, which contain from 4 to 8% praseodymium. Plant capacity involving liquid-liquid or solid-liquid organic ion-exchange processes for recovering the element is in excess of 100.000 pounds PreOn annually. Metallic praseodymium is obtained by electrolysis of Pr O] in a molten fluoride electrolyte, or by a calcium reduction of PrFj or PrCls in a sealed-bomb reaction. 

By far, the most studied quantum cutting system to date is for praseodymium, where the 4f2 1 So state lies below the lowest 5d state for many fluorides and some oxides. For most Pr3+ doped systems, the nephelauxetic effect and the 5d crystal field splitting are large enough to push the lowest 5d level below the 1 So state. However, for those systems in which the So... 

The lanthanides, unlike the transition metals and the actinides, tend not to form compounds over a range of oxidation states. The +3 oxidation state is characteristic of all of the lanthanides, and the oxide fluorides of formula LnOF (Ln = lanthanide metal) are well known. The less stable oxidation states of + 2 and + 4 are known, but the latter is represented only by the dioxides and tetrafluorides of cerium, praseodymium, and terbium, and no tetravalent oxide fluorides have been reported. 

This oxidation state is very important for cerium and of minor, though not negligible, importance for praseodymium and terbium. With the possible exception of a few fluorides, for example, Cs3LnF7 for Nd and Dy, no other Ln compounds are known. 

The solubility of rare earth fluorides REF3 is very low, the pXsp ranges from 19 to 15 for lighter rare earth lanthanum, cerium, praseodymium, and neodymium to heavier rare earth ytterbium and lutetium, respectively. 

Figure 1. Structure of first coordination sphere of fluorides around tetravalent praseodymium ion...

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