Praseodymium, separation of mixtures

Praseodymium, separation of mixtures with lanthanum from monazite, as magnesium nitrate double salt, 2 56, 67 Praseodymium (III) nitrate, analysis of anhydrous, 5 41 Praseodymium (III) oxide, for synthesis of nitrate, 5 39w. Precipitates, apparatus for removing liquid from, 8 16 Purpureochromic chloride, 2 196 6 138... 

Cement, laboratory, 1 189 Cerite, extraction of, 2 44 Cerium, phosphor containing strontium sulfide and, 3 23 separation of, from rare earth mixtures, 2 43, 47, 48 test for, 2 50 Cerium amalgam, 1 15 Cerium-group earths, separation of, from yttrium earths by doublesulfate method, 2 44, 46 Cerium (III) magnesium nitrate, 2Ce(N03)s-3Mg(N03)2-24H,0, separation of praseodymium from lanthanum by, 2 57 Cerium(III) nitrate, 2 51 Cerium (IV) nitrate, basic, 2 49 Cesium, cesium azide for preparation of, 1 79... 

Using a spectrometer in 1853, Jean Charles-GaUisard de Marignac (1817—1894) suspected that dydimia was a mixture of yet-to-be-discovered elements. However, it was not until 1879 that Paul-Emile Locoq de Boisbaudran (1838—1912), using a difficult chemical fractionation process, discovered samarium in a sample of samarskite, calling it samarium after the mineral, which was named for a Russian mine official. Colonel von Samarski. Samarskite ore is found where didymia is found. Didymia ( twins ) was the original name given to a combination of the two rare-earths (praseodymium and neodymium) before they were separated and identified. 

The final answer came from the atomic pile. J. A. Marinsky, L. E. Glendenin, and C. D. Coryell at the Clinton Laboratories at Oak Ridge (20) obtained a mixture of fission products of uranium which contained isotopes of yttrium and the entire group of rare earths from lanthanum through europium. Using a method of ion-exchange on Amberlite resin worked out by E. R. Tompkins, J. X. Khym, and W. E. Cohn (21) they were able to obtain a mixture of praseodymium, neodymium, and element 61, and to separate the latter by fractional elution from the Amberlite column with 5 per cent ammonium citrate at pH 2.75. Neutron irradiation of neodymium also produced 61. 

The chelates can be purified, and mixtures of the complexes can be separated by fractional sublimation and distillation. In the gas phase, in solution, and in the solid state, Tb(thd)3 emits a brilliant green fluorescence when irradiated at 3660 A. with an ultraviolet lamp. Fluorescence is also exhibited by Eu(thd)3, Dy(thd)3, and Sm(thd)3. The praseodymium complex is thermally stable in the gas phase when heated for prolonged periods of time. Vapor pressure measurements on this complex showed no increase in pressure when the sample was heated at 250° for 6 hours. Thermogravimetric analyses and discussions of trends in volatility of the rare-earth-thd chelates have been published. 

Auer von Weis bach in Austria developed a new separation method. If a mixture of RE oxides is attacked by nitric acid the most basic oxides dissolve, while the less basic will be enriched in the insoluble residue. By using this method he was able, in 1884, to separate lanthanum (the more basic) from didymium. He continued to apply the same method to the didymium fraction and carried out more than 100 fractional crystallizations, each taking two days. In this way didymium was separated into two main fractions. In 1885, spectroscopic studies confirmed that two different elements were present. Auer called the green-colored one praseodymium, the green twin", while the other got the name neodymium, the new twin". This naming has been accepted, although it involved a deviation from the earlier rule that when a supposedly pure RE metal is divided in two, one of the elements shall keep the older name, while the other is given a new name by the discoverer. 

D. W. Bareis, a Continuous Fission Product Separation Process. I. Removal of the Rare Earths Lanthanum, Cerium, Praseodymium, and Neodymium) from a Typical Liquid Bismuth—Uranium Reactor Fuel by Contact with Fused LiCl-KCl Mixture, USAEC Report BNL-125, Brookhaven National Laboratory, 1951. 

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