Estimation of the standard entropies of some Am(III) and Cm(III) compounds

The standard entropies S degrees (298.15 K) of some actinide(III) compounds have been estimated using a semi-empirical method describing the total entropy as the sum of the lattice entropy S-lat and the excess entropy S-exs. The validity of the applied approach has been verified for the iso-electronic lanthanide(III) compounds for which a good agreement with experimental values has been obtained. The present results for the actinide(III) compounds are compared to previous estimates. Significant differences have been found, in particular for the americium compounds. (C) 2001 Elsevier Science B.V. All rights reserved.