Publication Date

2-7-2018

Department

Ames Laboratory; Physics and Astronomy

Campus Units

Physics and Astronomy, Ames Laboratory

Report Number

IS-J 9595

Journal Title

Journal of the American Chemical Society

Volume Number

140

Issue Number

5

First Page

1674

Last Page

1685

Abstract

A series of f-block chromates, CsM(CrO4)(2) (M = La, Pr, Nd, Sm, Eu; Am), were prepared revealing notable differences between the Am-III derivatives and their lanthanide analogs. While all compounds form similar layered structures, the americium compound exhibits polymorphism and adopts both a structure isomorphous with the early lanthanides as well as one that possesses lower symmetry. Both polymorphs are dark red and possess band gaps that are smaller than the Ln(III) compounds. In order to probe the origin of these differences, the electronic structure of alpha-CsSm(CrO4)(2), alpha-CsEu(CrO4)(2), and alpha-CsAm(CrO4)(2) were studied using both a molecular cluster approach featuring hybrid density functional theory and QTAIM analysis and by the periodic LDA+GA and LDA+DMFT methods. Notably, the covalent contributions to bonding by the f orbitals were found to be more than twice as large in the Al-III chromate than in the Sm-III and Eu-III compounds, and even larger in magnitude than the Am-5f spin orbit splitting in this system. Our analysis indicates also that the Am-O covalency in alpha-CsAm(CrO4)(2) is driven by the degeneracy of the 5f and 2p orbitals, and not by orbital overlap.

DOE Contract Number(s)

SC0016568

Language

en

Department of Energy Subject Categories

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Thursday, January 10, 2019

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