On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View
Comparative exploration of the nanometer-scale atomic structure of KxFe2−yCh2 (Ch = S, Se) was performed using neutron total scattering-based atomic pair distribution function (PDF) analysis of 5 K powder diffraction data in relation to physical properties. Whereas KxFe2−ySe2 is...
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| Format: | Article |
| Language: | English |
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MDPI AG
2018-07-01
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| Series: | Condensed Matter |
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| Online Access: | http://www.mdpi.com/2410-3896/3/3/20 |
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| author | Panagiotis Mangelis Hechang Lei Marshall T. McDonnell Mikhail Feygenson Cedomir Petrovic Emil S. Bozin Alexandros Lappas |
| author_facet | Panagiotis Mangelis Hechang Lei Marshall T. McDonnell Mikhail Feygenson Cedomir Petrovic Emil S. Bozin Alexandros Lappas |
| author_sort | Panagiotis Mangelis |
| collection | DOAJ |
| description | Comparative exploration of the nanometer-scale atomic structure of KxFe2−yCh2 (Ch = S, Se) was performed using neutron total scattering-based atomic pair distribution function (PDF) analysis of 5 K powder diffraction data in relation to physical properties. Whereas KxFe2−ySe2 is a superconductor with a transition temperature of about 32 K, the isostructural sulphide analogue is not, which instead displays a spin glass semiconducting behavior at low temperatures. The PDF analysis explores phase separated and disordered structural models as candidate descriptors of the low temperature data. For both materials, the nanoscale structure is well described by the iron (Fe)-vacancy-disordered K2Fe5−yCh5 (I4/m) model containing excess Fe. An equally good description of the data is achieved by using a phase separated model comprised of I4/m vacancy-ordered and I4/mmm components. The I4/mmm component appears as a minority phase in the structure of both KxFe2−ySe2 and KxFe2−yS2, and with similar contribution, implying that the phase ratio is not a decisive factor influencing the lack of superconductivity in the latter. Comparison of structural parameters of the Fe-vacancy-disordered model indicates that the replacement of selenium (Se) by sulphur (S) results in an appreciable reduction in the Fe-Ch interatomic distances and anion heights, while simultaneously increasing the irregularity of FeCh4 tetrahedra, suggesting the more significant influence of these factors. Structural features are also compared to the non-intercalated FeSe and FeS parent phases, providing further information for the discussion about the influence of the lattice degrees of freedom on the observed properties in layered iron chalcogenides. |
| first_indexed | 2024-04-11T13:20:02Z |
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| institution | Directory Open Access Journal |
| issn | 2410-3896 |
| language | English |
| last_indexed | 2024-04-11T13:20:02Z |
| publishDate | 2018-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Condensed Matter |
| spelling | doaj.art-3da7b0b7d7454f31a1b9344f91ed848a2022-12-22T04:22:14ZengMDPI AGCondensed Matter2410-38962018-07-01332010.3390/condmat3030020condmat3030020On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function ViewPanagiotis Mangelis0Hechang Lei1Marshall T. McDonnell2Mikhail Feygenson3Cedomir Petrovic4Emil S. Bozin5Alexandros Lappas6Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas, Vassilika Vouton, 711 10 Heraklion, GreeceCondensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USANeutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USANeutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USACondensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USACondensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USAInstitute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas, Vassilika Vouton, 711 10 Heraklion, GreeceComparative exploration of the nanometer-scale atomic structure of KxFe2−yCh2 (Ch = S, Se) was performed using neutron total scattering-based atomic pair distribution function (PDF) analysis of 5 K powder diffraction data in relation to physical properties. Whereas KxFe2−ySe2 is a superconductor with a transition temperature of about 32 K, the isostructural sulphide analogue is not, which instead displays a spin glass semiconducting behavior at low temperatures. The PDF analysis explores phase separated and disordered structural models as candidate descriptors of the low temperature data. For both materials, the nanoscale structure is well described by the iron (Fe)-vacancy-disordered K2Fe5−yCh5 (I4/m) model containing excess Fe. An equally good description of the data is achieved by using a phase separated model comprised of I4/m vacancy-ordered and I4/mmm components. The I4/mmm component appears as a minority phase in the structure of both KxFe2−ySe2 and KxFe2−yS2, and with similar contribution, implying that the phase ratio is not a decisive factor influencing the lack of superconductivity in the latter. Comparison of structural parameters of the Fe-vacancy-disordered model indicates that the replacement of selenium (Se) by sulphur (S) results in an appreciable reduction in the Fe-Ch interatomic distances and anion heights, while simultaneously increasing the irregularity of FeCh4 tetrahedra, suggesting the more significant influence of these factors. Structural features are also compared to the non-intercalated FeSe and FeS parent phases, providing further information for the discussion about the influence of the lattice degrees of freedom on the observed properties in layered iron chalcogenides.http://www.mdpi.com/2410-3896/3/3/20neutron pair distribution function (PDF)intercalated iron superconductorsanion heighttetrahedron regularity |
| spellingShingle | Panagiotis Mangelis Hechang Lei Marshall T. McDonnell Mikhail Feygenson Cedomir Petrovic Emil S. Bozin Alexandros Lappas On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View Condensed Matter neutron pair distribution function (PDF) intercalated iron superconductors anion height tetrahedron regularity |
| title | On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View |
| title_full | On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View |
| title_fullStr | On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View |
| title_full_unstemmed | On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View |
| title_short | On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View |
| title_sort | on the nanoscale structure of kxfe2 ych2 ch s se a neutron pair distribution function view |
| topic | neutron pair distribution function (PDF) intercalated iron superconductors anion height tetrahedron regularity |
| url | http://www.mdpi.com/2410-3896/3/3/20 |
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