Praesodymium

Cathode Porous Pt Stabilized Zr02 impregnated with praesodymium oxide and covered with SnO doped In203 Doped lanthanum manganite Extrusion, sintering 2 mm thickness 11 X 10 cm/cm°C expansion from room temperature to 1000°C 30-40% porosity... 

Praesodymium may be recovered from its minerals monazite and bastana-site. The didymia extract of rare earth minerals is a mixture of praesodymia and neodymia, primarily oxides of praesodymium and neodymium. Several methods are known for isolation of rare earths. These are applicable to all rare earths including praesodymium. They include solvent extractions, ion-exchange, and fractional crystallization. While the first two methods form easy and rapid separation of rare earth metals, fractional crystaUization is more tedious. Extractions and separations of rare earths have been discussed in detail earlier (see Neodymium and Cerium). 

Praesodymium metal can be obtained from its anhydrous halides by reduction with calcium. The metal also may be prepared by electrolysis of fused praesodymium chloride at elevated temperatures (about 1,000°C). Alternatively, an eutectic mixture of praesodymium chloride, potassium chloride, and sodium chloride may be electrolyzed. In such electrolysis graphite is the anode and tungsten the cathode. 

Praesodymium salts containing oxo anions such as sulfate, hydroxide, carbonate, silicates, oxalate, thiosulfate, chromate, molybdate, and borate are known. 

Praesodymium salts can be identified nondestructively by x-ray diffraction. The metal can be analyzed by atomic absorption or emission spectroscopy. The water insoluble oxide and other compounds may be digested with aqua regia, diluted, and analyzed by AA or ICP. 

Spectrum of the Glowing Oxide.—Neodymium oxide is one of the very few solids with a discontinuous spectrum. The spectrum which was known long before neodymium was separated from its fellow element praesodymium, was briefly described by Bunsen1 in 1864, who in the same communication mentions the discovery by Bahr2 of the similarly banded spectrum of erbium oxide. Thus far, however, no thorough-going study seems to have been made of this class of spectrum. 

On heating, all of the anhydrous sulfates of the trivalent rare-earth elements and yttrium, type formula R2(S04)3 decompose, without first melting, to basic salts (oxysulfates) of the type R203.S03, then to an oxide. The oxide final product is R203 for all the elements except cerium, praesodymium,... 

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