Origins of the odd optical observables in plutonium and americium tungstates

Justin N. Cross; Tsung Han Lee; Chang Jong Kang; Yong Xin Yao; Samantha K. Cary; Jared T. Stritzinger; Matthew J. Polinski; Carla D. McKinley; Thomas E.Albrecht Schmitt; Nicola Lanata

doi:10.1039/c9sc01174a

Origins of the odd optical observables in plutonium and americium tungstates

Justin N. Cross, Tsung Han Lee, Chang Jong Kang, Yong Xin Yao, Samantha K. Cary, Jared T. Stritzinger, Matthew J. Polinski, Carla D. McKinley, Thomas E.Albrecht Schmitt, Nicola Lanata

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

A series of trivalent f-block tungstates, MW₂O₇(OH)(H₂O) (M = La, Ce, Pr, Nd, and Pu) and AmWO₄(OH), have been prepared in crystalline form using hydrothermal methods. Both structure types take the form of 3D networks where MW₂O₇(OH)(H₂O) is assembled from infinite chains of distorted tungstate octahedra linked by isolated MO₈ bicapped trigonal prisms; whereas AmWO₄(OH) is constructed from edge-sharing AmO₈ square antiprisms connected by distorted tungstate trigonal bipyramids. PuW₂O₇(OH)(H₂O) crystallizes as red plates; an atypical color for a Pu(iii) compound. Optical absorption spectra acquired from single crystals show strong, broadband absorption in the visible region. A similar feature is observed for CeW₂O₇(OH)(H₂O), but not for AmWO₄(OH). Here we demonstrate that these significantly different optical properties do not stem directly from the 5f electrons, as in both systems the valence band has mostly O-2p character and the conduction band has mostly W-5d character. Furthermore, the quasi-particle gap is essentially unaffected by the 5f degrees of freedom. Despite this, our analysis demonstrates that the f-electron covalency effects are quite important and substantially different energetically in PuW₂O₇(OH)(H₂O) and AmWO₄(OH), indicating that the optical gap alone cannot be used to infer conclusions concerning the f electron contribution to the chemical bond in these systems.

Original language	English
Pages (from-to)	6508-6518
Number of pages	11
Journal	Chemical Science
Volume	10
Issue number	26
DOIs	https://doi.org/10.1039/c9sc01174a
State	Published - 2019
Externally published	Yes

Funding

All experimental studies were supported by the U.S. Department of Energy, Basic Energy Sciences, Heavy Elements Chemistry Program, U.S. Department of Energy, under Grant DE-FG02-13ER16414. Theoretical studies were supported by the U.S. Department of Energy as a part of the Center for Actinide Science and Technology (CAST) funded by the Energy Frontiers Research Program, under Award Number DE-SC0016568. N. L. was also supported by the VILLUM FONDEN via the Centre of Excellence for Dirac Materials (Grant No. 11744). T.-H. L and C.-J. K were supported by the Department of Energy under Grant No. DE-FG02-99ER45761. Y. Y. was supported by the U.S. Department of energy, Office of Science, Basic Energy Sciences, as a part of the Computational Materials Science Program. This work used the Extreme Science and Engineering Discovery Environment (XSEDE) funded by NSF under Grants No. TG-DMR170121.

Funders	Funder number
Center for Actinide Science and Technology	DE-SC0016568
Heavy Elements Chemistry Program
National Science Foundation
U.S. Department of Energy	DE-FG02-13ER16414
Office of Science
Basic Energy Sciences
Villum Fonden	11744

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@article{555800a16f3b4c7ca5925a95e771e790,

title = "Origins of the odd optical observables in plutonium and americium tungstates",

abstract = "A series of trivalent f-block tungstates, MW2O7(OH)(H2O) (M = La, Ce, Pr, Nd, and Pu) and AmWO4(OH), have been prepared in crystalline form using hydrothermal methods. Both structure types take the form of 3D networks where MW2O7(OH)(H2O) is assembled from infinite chains of distorted tungstate octahedra linked by isolated MO8 bicapped trigonal prisms; whereas AmWO4(OH) is constructed from edge-sharing AmO8 square antiprisms connected by distorted tungstate trigonal bipyramids. PuW2O7(OH)(H2O) crystallizes as red plates; an atypical color for a Pu(iii) compound. Optical absorption spectra acquired from single crystals show strong, broadband absorption in the visible region. A similar feature is observed for CeW2O7(OH)(H2O), but not for AmWO4(OH). Here we demonstrate that these significantly different optical properties do not stem directly from the 5f electrons, as in both systems the valence band has mostly O-2p character and the conduction band has mostly W-5d character. Furthermore, the quasi-particle gap is essentially unaffected by the 5f degrees of freedom. Despite this, our analysis demonstrates that the f-electron covalency effects are quite important and substantially different energetically in PuW2O7(OH)(H2O) and AmWO4(OH), indicating that the optical gap alone cannot be used to infer conclusions concerning the f electron contribution to the chemical bond in these systems.",

author = "Cross, {Justin N.} and Lee, {Tsung Han} and Kang, {Chang Jong} and Yao, {Yong Xin} and Cary, {Samantha K.} and Stritzinger, {Jared T.} and Polinski, {Matthew J.} and McKinley, {Carla D.} and Schmitt, {Thomas E.Albrecht} and Nicola Lanata",

note = "Publisher Copyright: {\textcopyright} 2019 The Royal Society of Chemistry.",

year = "2019",

doi = "10.1039/c9sc01174a",

language = "English",

volume = "10",

pages = "6508--6518",

journal = "Chemical Science",

issn = "2041-6520",

publisher = "Royal Society of Chemistry",

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TY - JOUR

T1 - Origins of the odd optical observables in plutonium and americium tungstates

AU - Cross, Justin N.

AU - Lee, Tsung Han

AU - Kang, Chang Jong

AU - Yao, Yong Xin

AU - Cary, Samantha K.

AU - Stritzinger, Jared T.

AU - Polinski, Matthew J.

AU - McKinley, Carla D.

AU - Schmitt, Thomas E.Albrecht

AU - Lanata, Nicola

PY - 2019

Y1 - 2019

N2 - A series of trivalent f-block tungstates, MW2O7(OH)(H2O) (M = La, Ce, Pr, Nd, and Pu) and AmWO4(OH), have been prepared in crystalline form using hydrothermal methods. Both structure types take the form of 3D networks where MW2O7(OH)(H2O) is assembled from infinite chains of distorted tungstate octahedra linked by isolated MO8 bicapped trigonal prisms; whereas AmWO4(OH) is constructed from edge-sharing AmO8 square antiprisms connected by distorted tungstate trigonal bipyramids. PuW2O7(OH)(H2O) crystallizes as red plates; an atypical color for a Pu(iii) compound. Optical absorption spectra acquired from single crystals show strong, broadband absorption in the visible region. A similar feature is observed for CeW2O7(OH)(H2O), but not for AmWO4(OH). Here we demonstrate that these significantly different optical properties do not stem directly from the 5f electrons, as in both systems the valence band has mostly O-2p character and the conduction band has mostly W-5d character. Furthermore, the quasi-particle gap is essentially unaffected by the 5f degrees of freedom. Despite this, our analysis demonstrates that the f-electron covalency effects are quite important and substantially different energetically in PuW2O7(OH)(H2O) and AmWO4(OH), indicating that the optical gap alone cannot be used to infer conclusions concerning the f electron contribution to the chemical bond in these systems.

AB - A series of trivalent f-block tungstates, MW2O7(OH)(H2O) (M = La, Ce, Pr, Nd, and Pu) and AmWO4(OH), have been prepared in crystalline form using hydrothermal methods. Both structure types take the form of 3D networks where MW2O7(OH)(H2O) is assembled from infinite chains of distorted tungstate octahedra linked by isolated MO8 bicapped trigonal prisms; whereas AmWO4(OH) is constructed from edge-sharing AmO8 square antiprisms connected by distorted tungstate trigonal bipyramids. PuW2O7(OH)(H2O) crystallizes as red plates; an atypical color for a Pu(iii) compound. Optical absorption spectra acquired from single crystals show strong, broadband absorption in the visible region. A similar feature is observed for CeW2O7(OH)(H2O), but not for AmWO4(OH). Here we demonstrate that these significantly different optical properties do not stem directly from the 5f electrons, as in both systems the valence band has mostly O-2p character and the conduction band has mostly W-5d character. Furthermore, the quasi-particle gap is essentially unaffected by the 5f degrees of freedom. Despite this, our analysis demonstrates that the f-electron covalency effects are quite important and substantially different energetically in PuW2O7(OH)(H2O) and AmWO4(OH), indicating that the optical gap alone cannot be used to infer conclusions concerning the f electron contribution to the chemical bond in these systems.

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U2 - 10.1039/c9sc01174a

DO - 10.1039/c9sc01174a

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VL - 10

SP - 6508

EP - 6518

JO - Chemical Science

JF - Chemical Science

IS - 26

ER -

Origins of the odd optical observables in plutonium and americium tungstates

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