Ln-4f/ligand-2p covalence in BaLnO(3) and Cs(3)LnF(7) (Ln = Ce, Pr, Tb)

Detailed information on Ln-4f/ligand-2p covalence and on differences in cov alence between tetravalent Ln compounds with oxygen and fluorine was derive d from Ln-M-4,M-5 XANES and Ln-3d XPS spectra of BaLnO(3) and Cs(3)LnF(7) ( Ln = Ce, Pr, Tb). We show that the fine structures of the multi-peaked spec tra can be well reproduced by calculations based on the single-impurity And erson model supplemented by intra-atomic multiplet interaction. In this way , discrepancies between experiment and theory in previous studies of LnO(2) compounds could be resolved, like the question of covalence, which we find to be weaker for Tb(IV) as compared to Ce(TV) and Pr(IV) compounds. (C) 20 00 Elsevier Science B.V. All rights reserved.