Transplutonium element, preparative

Tricyclopentadienide complexes of many of the actinides are known (Ac = Th, U, Pu, Am, Cm, Bk, Cf). Indeed, these are the only cyclopentadienide complexes known for the transplutonium elements, where -(-3 is the most stable oxidation state. The transplutonium elements were all prepared by a microchemical procedure which utilized a melt of biscyclopentadienyl beryllium (6) according to ... 

The development of the program for the production of transplutonium elements, americium 241, americium 243 and curium 244 in France required a major effort from the technological and chemical standpoints. Pre-existing hot cells were reconditioned and others were specially built for these production operations. From the chemical standpoint, the development of extractive chromatography on the preparative scale has allowed the definition of simple processes whose performance characteristics in our operating conditions have proved to be better than those obtained by liquid-liquid extraction. This type of process, initially developed for the treatment of Pu/Al targets, is ideal for the treatment of industrial wastes for their decontamination and for the production of americium 241. 

Ross, R. G. Wiggins, J. T. "Preparation of Curium-Americium Oxide Microspheres by Resin-Bead Loading", paper presented at Symposium on Industrial Scale Production-Separation-Recovery of Transplutonium Elements, 2nd Chem. Congr. North American Continent, Las Vegas, NV, 1980. 

Green solutions believed to be Am are prepared by oxidation of Am in concentrated aqueous basic solution by either ozone or the O radical. In contrast to Np, and similar to Pu, Am is unstable and reduces to the hexavalent state within minutes. A review on the chemistry of heptavalent transplutonium elements can be found in the Handbook of the Physics and Chemistry of the Actinides. ... 

In Table I are summarized some generally useful chemical reactions for the preparation of transplutonium element metal and some compounds. For simplicity, and because of variable oxidation states, the equations are not necessarily balanced. 

Table I. Preparative Chemistry for Transplutonium Element (An) Metal and Some Compounds...

For Th, U, and Pu the starting materials for research samples are often metals prepared external to the laboratory by larger-scale processing. On the other hand, for the transplutonium elements, and Pa and Np, laboratory-scale preparation predominates, and the major preparation routes involve pyrometallurgy combined with vapor transport. 

One of the requirements of any nuclear facility is to monitor the effluent uxiste water to show compliance with existing standards. This paper describes a sequential procedure for the separation of the transuranic elements from water samples up to 60 1. The elements of interest are coprecipitated with calcium fluoride and then individually separated using a combination of ion exchange and solvent extraction, with a final sample preparation by electrodeposition. Alpha spectrometry of these samples allows the measurement of neptunium, plutonium, and transplutonium nuclides at sub-fCi/l, levels. 

In contrast to the early actinide compounds already discussed, the iodates of the transplutonium actinides that have been prepared contain trivalent oxidation states for the actinide elements. For Am, several higher oxidation states are possible, but attempts to prepare Am(V) or Am(VI) analogs of these iodates... 

The major breakthrough occurred in 1953 when the Ames Laboratory team (Daane et al. 1953) reported the preparation of samarium, europium and ytterbium in high purity and high yields by the reduction of their oxides with lanthanum metal in a vacuum. With the preparation of samarium metal, finally, 126 years after the first rare earth element was reduced to its metallic state, all of the naturally occurring rare earths were now available in their elemental state in sufficient quantity and purity to measure their physical and chemical properties. The success of this reaction is due to the low vapor pressure of lanthanum and the extremely high vapor pressures of samarium, europium and ytterbium (Daane 1951, 1961, Habermann and Daane 1961). It is interesting to note that this same technique has been the method of choice for the preparation of some transplutonium metals (Cunningham 1964). 

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