Stability and optical properties of plutonium monoxide from first-principle calculation

Qiu, Ruizhi; Zhang, Yongbin; Ao, Bingyun

doi:10.1038/s41598-017-12428-x

Cited by 17 publications

(18 citation statements)

References 42 publications

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“…This holds for the some nonmetallic elements such as H and N with weak oxidizability judged from their borderline compounds PuH 3 and PuN . Pu 2+ had not been detected in the binary compounds for a long time; even the unstable PuH 2 and PuO (exactly, stabilized by C, i.e., PuC x O 1– x ) were determined to be trivalent-like Pu ions with a surplus 5f conduction electron, resulting in the metallic states of PuH 2 and PuO, whereas PuH 3 and Pu 2 O 3 are semiconducting states. − Clearly, the valence or OS can be readily changed by more electronegative elements. With the transition of Pu 2 O 3 → PuO 2 → PuO 2+ x , , Pu 5f electrons become more delocalized with the typical feature of fewer 5f states below Fermi energy ( E F ) and are expected to be further delocalized in the crystallographically identified Pu–O–F ternary solid compounds, such as PuO 2 F, PuO 2 F 2 , and PuOF 4 .…”

Section: Introductionmentioning

confidence: 99%

Plutonium Oxidation States in Complex Molecular Solids

Qiu

2019

J. Phys. Chem. C

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Oxidation state is a key chemical quantity that allows the understanding and prediction of the majority of chemical reactions; however, the main deficiency using the formal oxidation state comes from the materials containing multivalent metals. Among them, the most complicated element plutonium (Pu) is an outstanding instance. Here, we calculate the orbital occupation numbers under the frameworks of firstprinciples density functional theory (DFT) + U methods to quantitatively determine the Pu-oxidation state of the recently reported complex molecular solids: [K(crypt)]Pu-[C 5 H 3 (SiMe 3 ) 2 ] 3 , Pu 3 (DPA) 5 (H 2 O) 2 , and Pu 3 (DPA) 6 H. The results show that the oxidation state of Pu is an extremely low Pu 2+ in the former and a mixed Pu 3+ /Pu 4+ in the latter two compounds, which is consistent with the experimental identifications. The steric effects and the environmentally sensitive localization → delocalization transition of Pu 5f electrons can rationally elucidate the formation of the unusual oxidation states. Such atomic-resolution quantitative determination of the unusual Pu oxidation states in the complex molecular solids offers an alternative for the further exploration of peculiar Pu solid-state materials.

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Section: Introductionmentioning

confidence: 99%

Plutonium Oxidation States in Complex Molecular Solids

Qiu

2019

J. Phys. Chem. C

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“…to illustrate that PuO is thermodynamically unstable at ambient pressure and will probably decompose into Pu 2 O 3 and Pu. 15 A number of researchers have suggested that PuO could be stabilized by carbon impurity. [11][12][13]18 The further question is about the thermodynamical stability of carbonsubstituted PuO, i.e., PuO x C y , with respect to Pu 2 O 3 and Pu.…”

Section: ■ Introductionmentioning

confidence: 99%

Thermodynamical Stability of Plutonium Monoxide with Carbon Substitution

et al. 2018

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The existence of condensed plutonium monoxide (PuO) has long been controversial, in which carbon element plays a vital role. In this work, we modeled PuO with carbon substitution of oxygen as the special quasirandom structures of NaCl-type plutonium monoxycarbide (PuO x C 1−x ) and performed first-principles calculations on these models. It is found that PuO could indeed be stabilized by carbon substitution. The amount of carbon element to stabilize PuO is very small if the source of carbon is CO or CO 2 . If the carbon is contributed by plutonium monocarbide, the range of stable PuO x C 1−x agrees well with the experimental result. By analyzing the electronic structures and chemical bonds, we ascribe the stabilization of PuO by carbon substitution to the newly established Pu 5f/6d−C 2p hybridization around the Fermi level, i.e., stronger Pu−C bonds.

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“…In other words, limited oxygen vacancies weaken the strength of the Ce–O bonds; however, they cannot fundamentally alter the electron-match character until the borderline Ce 2 O 3 . Further removing oxygen from Ce 2 O 3 is expected to result in a metallic state, similar to the analogue Pu 2 O 3 and other low valence metal oxides. , …”

Section: Results and Discussionmentioning

confidence: 95%

“…The DOS profiles of stoichiometric oxides or impurity-doped oxides allow us to find whether or not the in-gap states resultant from localized electrons are formed. 42 43,44 The changes in the band gap and energy profile are bound to be reflected in the electronic and optical response, which establishes the basic principle for tailoring ceria. The changes are particularly remarkable for the ternary and quaternary Ce oxides, as shown in Figure 4.…”

Section: Computational Approachmentioning

confidence: 99%

First-Principles Insights into the Oxidation States and Electronic Structures of Ceria-Based Binary, Ternary, and Quaternary Oxides

Qiu

2018

J. Phys. Chem. C

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Ceria and ceria-based materials have versatile technological and industrial applications physically ascribed to the flexible fluctuation of the Ce oxidation state between Ce4+ and Ce3+. Considerable multidisciplinary research has been carried out to obtain the Ce oxidation state, which is crucial for their application; however, a rigorous and physically correct determination of the oxidation state is still lacking. Here, we conduct first-principles DFT + U calculations to unambiguously determine the physical oxidation state of Ce in ceria-based materials, such as homogenous Ce n O2n–2 (n = 7, 9, 10, 11, and 12), ceria doped by multivalent Ti and V, Ce–Ti(V)–O ternary compounds, and Ce–Ti–V–O quaternary compounds. The results show that the Ce oxidation state depends on the local structure and chemical surrounding: oxygen vacancy facilitates the transition from Ce4+ to Ce3+, which is consistent with the localization of Ce 4f electrons; Ti and V with the 3d energy levels higher than 4f energy levels of Ce generally tend to reduce Ce4+ to Ce3+, particularly under an oxygen-deficient condition. The atom-resolved determination of the Ce oxidation states in complicated compounds offers great promise for understanding the physical and chemical behavior of ceria-based materials and for rational design of novel ceria-based materials for application potentials.

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Stability and optical properties of plutonium monoxide from first-principle calculation

Cited by 17 publications

References 42 publications

Plutonium Oxidation States in Complex Molecular Solids

Plutonium Oxidation States in Complex Molecular Solids

Thermodynamical Stability of Plutonium Monoxide with Carbon Substitution

First-Principles Insights into the Oxidation States and Electronic Structures of Ceria-Based Binary, Ternary, and Quaternary Oxides

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