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 ent ropy 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-electron ic lanthanide(III) compounds for which a good agreement with experimental v alues has been obtained. The present results for the actinide(III) compound s are compared to previous estimates. Significant differences have been fou nd, in particular for the americium compounds. (C) 2001 Elsevier Science B. V. All rights reserved.