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Title: Uncovering the Origin of Divergence in the CsM(CrO 4) 2 (M = La, Pr, Nd, Sm, Eu; Am) Family through Examination of the Chemical Bonding in a Molecular Cluster and by Band Structure Analysis

A series of f-block chromates, CsM(CrO 4) 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 α-CsSm(CrO 4) 2, α-CsEu(CrO 4) 2, and α-CsAm(CrO 4) 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 Am 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 α-CsAm(CrO 4) 2 is driven by the degeneracy of the 5f and 2p orbitals, and not by orbital overlap.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ; ORCiD logo [3] ;  [1] ;  [1] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7] ; ORCiD logo [4] ; ORCiD logo [8] ;  [7]
  1. Florida State Univ., Tallahassee, FL (United States). Department of Chemistry and Biochemistry
  2. Rutgers Univ., Piscataway, NJ (United States). Department of Physics and Astronomy
  3. Ames Lab. and Iowa State Univ., Ames, IA (United States). Department of Physics and Astronomy
  4. Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
  5. Department of Physics, Florida State University, Tallahassee, Florida 32306, United States; National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
  6. National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States; Department of Chemical Engineering, Florida State University, Tallahassee, Florida 32310, United States
  7. National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
  8. School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
Publication Date:
Report Number(s):
IS-J-9584
Journal ID: ISSN 0002-7863
Grant/Contract Number:
AC02-07CH11358; SC0016568
Type:
Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 140; Journal Issue: 5; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
OSTI Identifier:
1434561
Alternate Identifier(s):
OSTI ID: 1427725