Single-Crystal Structures, Optical Absorptions, and Electronic Distributions of Thorium Oxychalcogenides ThOQ (Q = S, Se, Te)

Koscielski, Lukasz A.; Ringe, Emilie; Duyne, Richard P. Van; Ellis, Donald E; Ibers, James A.

doi:10.1021/ic300510x

Cited by 21 publications

(15 citation statements)

References 30 publications

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“…The reaction product contained dark-red crystals of Ba 3 ThSe 3 (Se 2 ) 2 (Ba:Th:Se≈3:1:7), black columnar crystals of Sb 2 Se 3 [31] (Sb:Se≈2:3), red crystals of BaSe, copper-colored crystals of Th 2 Se 5 [10] (Th:Se≈2:5), and plate-shaped red crystals of ThOSe [32]. Crystals of Ba 3 ThSe 3 (Se 2 ) 2 were subsequently obtained from the stochiometric reaction of the elements using the same heating conditions.…”

Section: Synthesesmentioning

confidence: 99%

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Prakash

Mesbah

Beard

et al. 2015

Journal of Solid State Chemistry

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Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba 3 ThSe 3 (Se 2 ) 2 Journal of Solid State Chemistry, http://dx.Abstract The compound Ba 3 ThSe 3 (Se 2 ) 2 has been synthesized by solid-state methods at 1173 K. Its crystal structure features one dimensional chains of 1 ∞ [Th(Se) 3 (Se 2 ) 2 6− ] separated by Ba 2+ cations. Each Th atom in these chains is coordinated to two Se−Se single-bonded pairs and four Se atoms to give rise to a pseudoocthedral geometry around Th. The Th−Se distances are consistent with Th 4+ and hence charge balance of Ba 3 ThSe 3 (Se 2 ) 2 is achieved as 3 × Ba 2+ , 1 × Th 4+ , 3 × Se 2− , and 2 × Se 2 2−. From optical measurements the band gap of Ba 3 ThSe 3 (Se 2 ) 2 is 1.96(2) eV.DFT calculations indicate that the compound is a semiconductor.

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Section: Synthesesmentioning

confidence: 99%

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Prakash

Mesbah

Beard

et al. 2015

Journal of Solid State Chemistry

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“…The EDX study on black irregularly shaped crystals showed the presence of Ba 2 Ag 2 Se 2 (Se 2 ) (Ba:Ag:Se ≈ 1:2:2). Other secondary phases present in the reaction product were orange plates of ThOSe (Th:Se ≈ 1:1) 35 and red blocks of BaSe (Ba:Se ≈ 1:1). 36 The synthesis of single crystals of Ba 2 Ag 2 Se 2 (Se 2 ) was further carried out by the stoichiometric reaction of BaSe (40.1 mg, 1.85 mmol), Ag (20 mg, 1.85 mmol), and Se (14.6 mg, 1.85 mmol) powders in an evacuated carbon-coated fused-silica tube.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Synthesis and Characterization of Ba₂Ag₂Se₂(Se₂)

et al. 2019

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Single crystals and a polycrystalline sample of Ba2Ag2Se2(Se2) were synthesized by standard solid-state chemistry methods at 1173 and 973 K, respectively. The crystal structure of this ternary compound was established by single-crystal X-ray diffraction studies at 100(2) K. The superstructure of this compound is commensurate and crystallizes in the space group P21/c of a monoclinic system with cell constants of a = 6.1766(2) Å, b = 6.1788(2) Å, c = 21.5784(8) Å, and β = 90.02(1)° (Z = 4). The asymmetric unit of the superstructure comprises eight atoms occupying general positions: two Ba atoms, two Ag atoms, and four Se atoms. In this structure, each Ag atom is tetrahedrally coordinated with four adjacent Se atoms to form distorted AgSe4 units that share edges with the neighboring tetrahedra to form a two-dimensional [AgSe4/4]− layer. These layers are separated by Ba2+ and Se2 2– units. The presence of the Se2 2– unit is also supported by an intense band at around 247 cm–1 in the Raman spectrum of Ba2Ag2Se2(Se2). A density functional theory study shows that the compound is a semiconductor with a calculated band gap of 1.1 eV. As determined by UV–visible spectroscopy, the direct and indirect band gaps are 1.23(2) and 1.10(2) eV, respectively, in good agreement with the theory and consistent with the black color of the compound. A temperature-dependent resistivity study also confirms the semiconducting nature of Ba2Ag2Se2(Se2).

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“…The exchange-correlation functional with generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE)40 was used to solve the Kohn-Sham equations with a kinetic energy cutoff of 600 eV. Since none of the localized 5f-like band is occupied in Th, the DFT with the GGA approximation was proved to be effective enough to describe the structural and vibrational properties of Th-based compounds11414243. The free energy global minimization of ThC 2 were performed by merging ab initio total energy calculations and particle-swarm optimization algorithm19 on structural predictions, as implemented in the CALYPSO code20.…”

Section: Methodsmentioning

confidence: 99%

Pressure-induced structural transformations and polymerization in ThC2

Guo

Lin

et al. 2017

Sci Rep

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Thorium-carbon systems have been thought as promising nuclear fuel for Generation IV reactors which require high-burnup and safe nuclear fuel. Existing knowledge on thorium carbides under extreme condition remains insufficient and some is controversial due to limited studies. Here we systematically predict all stable structures of thorium dicarbide (ThC2) under the pressure ranging from ambient to 300 GPa by merging ab initio total energy calculations and unbiased structure searching method, which are in sequence of C2/c, C2/m, Cmmm, Immm and P6/mmm phases. Among these phases, the C2/m is successfully observed for the first time via in situ synchrotron XRD measurements, which exhibits an excellent structural correspondence to our theoretical predictions. The transition sequence and the critical pressures are predicted. The calculated results also reveal the polymerization behaviors of the carbon atoms and the corresponding characteristic C-C bonding under various pressures. Our work provides key information on the fundamental material behavior and insights into the underlying mechanisms that lay the foundation for further exploration and application of ThC2.

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Single-Crystal Structures, Optical Absorptions, and Electronic Distributions of Thorium Oxychalcogenides ThOQ (Q = S, Se, Te)

Cited by 21 publications

References 30 publications

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Synthesis and Characterization of Ba₂Ag₂Se₂(Se₂)

Pressure-induced structural transformations and polymerization in ThC2

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Single-Crystal Structures, Optical Absorptions, and Electronic Distributions of Thorium Oxychalcogenides ThOQ (Q = S, Se, Te)

Cited by 21 publications

References 30 publications

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Synthesis and Characterization of Ba2Ag2Se2(Se2)

Pressure-induced structural transformations and polymerization in ThC2

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Synthesis and Characterization of Ba₂Ag₂Se₂(Se₂)