Actinide elements chalcogenides

WES/GRO] Westrum, Jr., E. F., Gronvold, F., Chemical thermodynamics of the actinide element chalcogenides. Thermodynamics of nuclear materials, Proc. Int. Symp., held in Vienna, Austria,21-25 May 1962, pp.3-37. International Atomic Energy Agency, Vienna,... 

Wei E.F. Westrum, Jr., F. Gronwald Chemical Thermodynamics of the Actinide Element Chalcogenides, Proc. Symp. ofThermodyn. of Nucl. Mat., IAEA, STI-Pub. 58, pp. 3-37, Vienna, 1962. 

In actinide binary compounds an equation of state can also be developed on the same lines. The difference in electronegativity of the actinide and the non-actinide element plays an important role, determining the degree of mixing between the actinide orbitals (5 f and 6 d) and the orbitals of the ligand. A mixture of metallic, ionic and covalent bond is then encountered. In the chapter, two classes of actinide compounds are reviewed NaCl-structure pnictides or chalcogenides, and oxides. 

The isomorphism of the lanthanide and actinide B1 compounds allows the bond-length variation to be visualized by simply plotting the lattice parameters. This was done in fig. 2 for the monocarbides (a), the monopnictides (b), and the mono-chalcogenides (c). As in the case of the pure actinide metals (Manes and Benedict 1985), bond shortening is observed for the actinides Pa to Pu, with respect to the other actinides and to the corresponding lanthanide compounds. This effect is most clearly marked for the compounds with the lighter non-actinide elements (e.g. N, P, S, Se) and becomes weaker with increasing Z of the non-actinide partner. Like in... 

Gronvold, F., Drowart, J., and Westrum, E. F., Jr (1984) The Chemical Thermodynandcs of Actinide Elements and Compounds, part 4, The Actinide Chalcogenides (Excluding Oxides), STI/PUB/424/4. International Atomic Energy Agency, Vienna. 

In the actinide compounds with the other group VI elements (X = S, Se, Te), the X/ An ratio varies from 1 to 3. These actinide chalcogenides show predominantly the composition AnX (cub.), AngXt (cub., orthorh.), AngXs (orthorh.), AnX2 (tetr.) and AnXg (orthorh.) which is also the order of decreasing thermal stability. 

Actinide chalcogenides can be obtained for instance by reaction of the elements, and thermal stability decreases S > Se > Te. Those of a given actinide differ from those of another in much the same way as do the oxides. Nonstoichiometry is again prevalent and, where the actinide appears to have an uncharacteristically low oxidation state, semimetallic behaviour is usually observed. 

The trend in the lattice constant of a given chalcogenide or pnictide across the actinide series differs from the trend for the elemental metals in that the dip in the... 

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