Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study
DFT calculations have been used to provide insights into the origin of the colossal positive and negative thermal expansion in Ag3[Co(CN) 6]. The results confirm that the positive expansion within the trigonal basal plane and the negative expansion in the orthogonal direction are coupled due to the...
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| Format: | Journal article |
| Language: | English |
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2008
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| _version_ | 1826269530842726400 |
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| author | Calleja, M Goodwin, A Dove, M |
| author_facet | Calleja, M Goodwin, A Dove, M |
| author_sort | Calleja, M |
| collection | OXFORD |
| description | DFT calculations have been used to provide insights into the origin of the colossal positive and negative thermal expansion in Ag3[Co(CN) 6]. The results confirm that the positive expansion within the trigonal basal plane and the negative expansion in the orthogonal direction are coupled due to the existence of a network defined by nearly rigid bonds within the chains of Co-C-N-Ag-N-C-Co linkages. The origin of the colossal values of the coefficients of thermal expansion arise from an extremely shallow energy surface that allows a flexing of the structure with small energy cost. The thermal expansion can be achieved with a modest value of the overall Grüneisen parameter. The energy surface is so shallow that we need to incorporate a small empirical dispersive interaction to give ground-state lattice parameters that match experimental values at low temperature. We compare the results with DFT calculations on two isostructural systems: H 3[Co(CN)6], which is known to have much smaller values of the coefficients of thermal expansion, and Au3[Co(CN)6], which has not yet been synthesized but which is predicted by our calculations to be another candidate material for showing colossal positive and negative thermal expansion. © 2008 IOP Publishing Ltd. |
| first_indexed | 2024-03-06T21:26:30Z |
| format | Journal article |
| id | oxford-uuid:4342e99c-ee63-4235-a423-49e2f662f034 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:26:30Z |
| publishDate | 2008 |
| record_format | dspace |
| spelling | oxford-uuid:4342e99c-ee63-4235-a423-49e2f662f0342022-03-26T14:54:23ZOrigin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory studyJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:4342e99c-ee63-4235-a423-49e2f662f034EnglishSymplectic Elements at Oxford2008Calleja, MGoodwin, ADove, MDFT calculations have been used to provide insights into the origin of the colossal positive and negative thermal expansion in Ag3[Co(CN) 6]. The results confirm that the positive expansion within the trigonal basal plane and the negative expansion in the orthogonal direction are coupled due to the existence of a network defined by nearly rigid bonds within the chains of Co-C-N-Ag-N-C-Co linkages. The origin of the colossal values of the coefficients of thermal expansion arise from an extremely shallow energy surface that allows a flexing of the structure with small energy cost. The thermal expansion can be achieved with a modest value of the overall Grüneisen parameter. The energy surface is so shallow that we need to incorporate a small empirical dispersive interaction to give ground-state lattice parameters that match experimental values at low temperature. We compare the results with DFT calculations on two isostructural systems: H 3[Co(CN)6], which is known to have much smaller values of the coefficients of thermal expansion, and Au3[Co(CN)6], which has not yet been synthesized but which is predicted by our calculations to be another candidate material for showing colossal positive and negative thermal expansion. © 2008 IOP Publishing Ltd. |
| spellingShingle | Calleja, M Goodwin, A Dove, M Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study |
| title | Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study |
| title_full | Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study |
| title_fullStr | Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study |
| title_full_unstemmed | Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study |
| title_short | Origin of the colossal positive and negative thermal expansion in Ag(3)[Co(CN)(6)]: an ab initio density functional theory study |
| title_sort | origin of the colossal positive and negative thermal expansion in ag 3 co cn 6 an ab initio density functional theory study |
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