Metals praseodymium

Figure 5f) may be attributed to metallic praseodymium because, based on the binding energy, the electron density of the praseodymium atom is probably high. 

No adsorption of carbon dioxide or oxygen was observed on either praseodymium chloride or oxychloride. This finding is consistent with the XPS results. The main peaks at 529 eV in the spectra for praseodymium oxychloride samples are also attributed to the lattice oxygen of the oxychloride while the peaks at 531 eV are assignable to O Is for praseodymium oxide, suggesting that the surfaces of the oxychloride samples are partially oxidized to praseodymium oxide. The 3d binding energy of 933 eV for praseodymium in the chloride and oxychloride implies that the valence of praseodymium is 3+, while the shoulder at 928 eV could be attributed to metallic praseodymium (77). 

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. 

B. Evans, Assistant Chemist. Rare-Earth Information Center. Energy itnd Mineral Resources Research Institute. Iowa Slate University. Ames. I,A. http //www.cxternal.ameslab.gov/. Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Lutetium Neodymium Rare-Earth Elements and Metals Praseodymium Samarium Scandium Terbium Thulium Ytterbium and Yttrium Daniel F. Farkas, Oregon State University. Corvallis. OR. http // oregonstate.edu/. Food Processing... 

Like many other metals, praseodymium also reacts with water and with acids. In these reactions, hydrogen gas is released. 

In 1885 C. A. von Welsbach isolated two elements as oxides, praseodymium (the word meaning green twin ) and neodymium (meaning new twin ), from a mixture of lanthanide oxides called didymia. The oxides can be transformed to fluorides by reaction with HF at 700°C (1,292°F), or with NH4HF2 at 300°C (572°F). The hydrated fluorides are then dehydrated in vacuo in a current of HF gas. The metals praseodymium and neodymium are obtained via metallothermic reduction with calcium at approximately 1,450°C (2,642°F), or via electrolytic reduction of the melts. The metals can also be obtained from anhydrous chlorides, obtained via reaction of the oxides with ammonium chloride at 350°C (662 °F), which are then reduced with lithium-magnesium at approximately 100°C (212°F). 

Al tshuler et al. (1981) report on ESR experiments on Er and Gd " " in metallic praseodymium. They investigated powdered samples with 1-3% Er or 10% Gd. At 4.2 K they obtain an Er " signal with g=8.7 0.05 and A//=200 25G. The authors assume that the ESR spectrum in bulk Pr is determined mainly by the Er ions that are substituted in a cubic environment (50% of the Er ions). Compared with metallic lanthanum (gu = 6.8), a large g-shift (Ag=+1.9) occurs, which is determined by two contributions The direct Pr-Gd exchange and an indirect exchange via conduction... 

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