Röntgenographische Untersuchungen und Strukturchemie von Chalkogenomolybdaten und ‐wolframaten

Müller, Achim; Sievert, W.

doi:10.1002/zaac.19744030305

Cited by 17 publications

(9 citation statements)

References 38 publications

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“…In the third Se site, Se 2− is bonded in a 5-coordinate geometry to four Na 1+ and one Mo 6+ atom. Our structural analysis is in agreement with the available information for its reported analogs [41][42][43][44][45]. Note, the intercalation of Na atoms could favor an energetically low-cost substitution (or displacement) of cations, enabling the tunability of ] − , it can be safely inferred that the crystal is a typical ionic conductor [45].…”

Section: B Structure and Symmetry Of Orthorhombic Sodium Molybdenum supporting

confidence: 88%

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Modeling the Ternary Chalcogenide Na2MoSe4 from First-Principles

Palos¹,

Reyes-Serrato²,

Alonso-Núñez³

et al. 2020

Preprint

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In the ongoing pursuit of inorganic compounds suitable for solid-state devices, transition metal chalcogenides have received heightened attention due to their physical and chemical properties. Recently, alkali-ion transition metal chalcogenides have been explored as promising candidates to be applied in optoelectronics, photovoltaics and energy storage devices. In this work, we present a comprehensive theoretical study of sodium molybdenum selenide (Na2MoSe4). First-principles computations were performed on a set of hypothetical crystal structures to determine the ground state and electronic properties of Na2MoSe4. We find that the equilibrium structure of Na2MoSe4 is a simple orthorhombic (oP) lattice, with space group Pnma, as evidenced by thermodynamics. Electronic structure computations reveal that three phases are semiconducting, while one (cF) is metallic. Relativistic effects and Coulomb interaction of localized electrons were assessed for the oP phase, and found to have a negligible influence on the band strucutre. Finally, meta-GGA computations were performed to model the band structure of primitive orthorhombic Na2MoSe4 at a predictive level. We employ the Tran-Blaha modified Becke-Johnson potential to demonstrate that oP Na2MoSe4 is a semiconductor with a direct bandgap of 0.53 eV at the Γ point. Our results provide a foundation for future studies concerned with the modeling of inorganic and hybrid organic-inorganic materials chemically analogous to Na2MoSe4.

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Section: B Structure and Symmetry Of Orthorhombic Sodium Molybdenum supporting

confidence: 88%

“…We match our evaluated structures to their analogs. First, we found our least stable candidate cF (F d − 3m) to be isostructural to the stable phase of Na [41][42][43][44][45] and could potentially be intrinsic semiconductors. Additionally, hybrid organic/inorganic members of the family R 2 MX 4 (e.g.…”

Section: A Candidate Structuresmentioning

confidence: 93%

Modeling the Ternary Chalcogenide Na2MoSe4 from First-Principles

Palos¹,

Reyes-Serrato²,

Alonso-Núñez³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…In the third Se site, Se 2− is bonded in a 5-coordinate geometry to four Na 1+ and one Mo 6+ atom. Our structural analysis is in agreement with the available information for its reported analogs [42][43][44][45][46]. Note, the intercalation of Na atoms could favor an energetically low-cost substitution (or displacement) of cations, enabling the tunability of these materials' properties.…”

Section: A Candidate Structuressupporting

confidence: 88%

“…Note, the intercalation of Na atoms could favor an energetically low-cost substitution (or displacement) of cations, enabling the tunability of these materials' properties. Lastly, due to the structure of Na + [MoSe 4 ] − , it can be safely inferred that the crystal is a typical ionic conductor [46].…”

Section: A Candidate Structuresmentioning

confidence: 99%

Modeling the ternary chalcogenide Na₂MoSe₄ from first-principles

Palos

Reyes-Serrato²,

Alonso-Núñez³

et al. 2020

J. Phys.: Condens. Matter

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In the ongoing pursuit of inorganic compounds suitable for solid-state devices, transition metal chalcogenides have received heightened attention due to their physical and chemical properties. Recently, alkali-ion transition metal chalcogenides have been explored as promising candidates to be applied in optoelectronics, photovoltaics and energy storage devices. In this work, we present a theoretical study of sodium molybdenum selenide (Na2MoSe4). First-principles computations were performed on a set of hypothetical crystal structures to determine the ground state and electronic properties of Na2MoSe4. We find that the equilibrium structure of Na2MoSe4 is a simple orthorhombic (oP ) lattice, with space group P nma, as evidenced by thermodynamics. Finally, meta-GGA computations were performed to model the band structure of oP Na2MoSe4 at a predictive level. We employ the Tran-Blaha modified Becke-Johnson potential to demonstrate that oP Na2MoSe4 has a direct bandgap at the Γ point that is suitable for optoelectronics. Our results provide a foundation for future studies concerned with the modeling of inorganic and hybrid organic-inorganic materials chemically analogous to Na2MoSe4.

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“…The compound is isostructural with other simple tetrathiomolybdate salts, M I 2 [MoS 4 ] (M I = NH 4 + , [29, 30] K + [31], Rb + [32], Cs + [33]) with all compounds adopting the β -K 2 SO 4 structure. The linear relationship between the sum of the ionic radii of the component elements and the unit cell volume, observed by Gattow and Franke [45] and Müller and Sievert [46, 47] for compounds of this general type, does not extend to Na 2 MoS 4 . The sizable thermal parameters for the Na + ions and the Na + … S distances, that exceed the sum of the ionic and van der Waals radii of Na + and sulfur, respectively, suggest that the Na + ions occupy oversized voids in a structure comprised of closely packed tetrathiomolybdate anions.…”

Section: Resultsmentioning

confidence: 92%

Molybdenum X-ray absorption edges from 200 to 20,000eV: The benefits of soft X-ray spectroscopy for chemical speciation

George

Drury

et al. 2009

Journal of Inorganic Biochemistry

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We have surveyed the chemical utility of the near-edge structure of molybdenum x-ray absorption edges from the hard x-ray K-edge at 20,000 eV down to the soft x-ray M 4,5 -edges at ~230 eV. We compared, for each edge, the spectra of two tetrahedral anions, MoO 4 and MoS 4 2-. We used three criteria for assessing near-edge structure of each edge: (i) the ratio of the observed chemical shift between MoO 4 2-and MoS 4 2-and the linewidth, (ii) the chemical information from analysis of the near-edge structure and (iii) the ease of measurement using fluorescence detection. Not surprisingly, the K-edge was by far the easiest to measure, but it contained the least information. The L 2,3 -edges, although harder to measure, had benefits with regard to selection rules and chemical speciation in that they had both a greater chemical shift as well as detailed lineshapes which could be theoretically analyzed in terms of Mo ligand field, symmetry, and covalency. The soft x-ray M 2,3 -edges were perhaps the least useful, in that they were difficult to measure using fluorescence detection and had very similar information content to the corresponding L 2,3 -edges.Interestingly, the soft x-ray, low energy (~230 eV) M 4,5 -edges had greatest potential chemical sensitivity and using our high resolution superconducting tunnel junction (STJ) fluorescence detector they appear to be straightforward to measure. The spectra were amenable to analysis using both the TT-multiplet approach and FEFF. The results using FEFF indicate that the sharp near-edge peaks arise from 3d → 5p transitions, while the broad edge structure has predominately 3d → 4f character. A proper understanding of the dependence of these soft x-ray spectra on ligand field and site geometry is necessary before a complete assessment of the utility of the Mo M 4,5 -* Corresponding author: sjgeorge@lbl.gov, +1 510 486 6094, FAX +1 510 486 5664. Supporting Information(1) Crystallographic data of Na 2 MoS 4 in CIF format.

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Röntgenographische Untersuchungen und Strukturchemie von Chalkogenomolybdaten und ‐wolframaten

Cited by 17 publications

References 38 publications

Modeling the Ternary Chalcogenide Na2MoSe4 from First-Principles

Modeling the Ternary Chalcogenide Na2MoSe4 from First-Principles

Modeling the ternary chalcogenide Na₂MoSe₄ from first-principles

Molybdenum X-ray absorption edges from 200 to 20,000eV: The benefits of soft X-ray spectroscopy for chemical speciation

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Röntgenographische Untersuchungen und Strukturchemie von Chalkogenomolybdaten und ‐wolframaten

Cited by 17 publications

References 38 publications

Modeling the Ternary Chalcogenide Na2MoSe4 from First-Principles

Modeling the Ternary Chalcogenide Na2MoSe4 from First-Principles

Modeling the ternary chalcogenide Na2MoSe4 from first-principles

Molybdenum X-ray absorption edges from 200 to 20,000eV: The benefits of soft X-ray spectroscopy for chemical speciation

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Modeling the ternary chalcogenide Na₂MoSe₄ from first-principles