Disordering of MgAl2O4 spinel from first principles
At high temperature, MgAl2O4 spinel is stabilized by disorder of Mg and Al between octahedral and tetrahedral sites. This behaviour has been measured up to 1700 K in recent neutron experiments, but the extrapolation of subsequently fitted thermodynamic models is not reliable. First principles simula...
| Main Authors: | , , |
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| Format: | Journal article |
| Language: | English |
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2000
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| _version_ | 1826279689378856960 |
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| author | Warren, M Dove, M Redfern, S |
| author_facet | Warren, M Dove, M Redfern, S |
| author_sort | Warren, M |
| collection | OXFORD |
| description | At high temperature, MgAl2O4 spinel is stabilized by disorder of Mg and Al between octahedral and tetrahedral sites. This behaviour has been measured up to 1700 K in recent neutron experiments, but the extrapolation of subsequently fitted thermodynamic models is not reliable. First principles simulation of the electronic structure of such minerals can in principle accurately predict disorder, but would require unfeasibly large computing resources. We have instead parameterized on-site and short-ranged cluster potentials using a small number of electronic structure simulations at zero temperature. These potentials were then used in large-scale statistical simulations at finite temperatures to predict disordering thermodynamics beyond the range of experimental measurements. Within the temperature range of the experiment, good agreement is obtained for the degree of order. The entropy and free energy are calculated and compared to those from macroscopic models. |
| first_indexed | 2024-03-07T00:02:31Z |
| format | Journal article |
| id | oxford-uuid:7673ba2b-9401-4530-996f-00194513ed82 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T00:02:31Z |
| publishDate | 2000 |
| record_format | dspace |
| spelling | oxford-uuid:7673ba2b-9401-4530-996f-00194513ed822022-03-26T20:16:19ZDisordering of MgAl2O4 spinel from first principlesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:7673ba2b-9401-4530-996f-00194513ed82EnglishSymplectic Elements at Oxford2000Warren, MDove, MRedfern, SAt high temperature, MgAl2O4 spinel is stabilized by disorder of Mg and Al between octahedral and tetrahedral sites. This behaviour has been measured up to 1700 K in recent neutron experiments, but the extrapolation of subsequently fitted thermodynamic models is not reliable. First principles simulation of the electronic structure of such minerals can in principle accurately predict disorder, but would require unfeasibly large computing resources. We have instead parameterized on-site and short-ranged cluster potentials using a small number of electronic structure simulations at zero temperature. These potentials were then used in large-scale statistical simulations at finite temperatures to predict disordering thermodynamics beyond the range of experimental measurements. Within the temperature range of the experiment, good agreement is obtained for the degree of order. The entropy and free energy are calculated and compared to those from macroscopic models. |
| spellingShingle | Warren, M Dove, M Redfern, S Disordering of MgAl2O4 spinel from first principles |
| title | Disordering of MgAl2O4 spinel from first principles |
| title_full | Disordering of MgAl2O4 spinel from first principles |
| title_fullStr | Disordering of MgAl2O4 spinel from first principles |
| title_full_unstemmed | Disordering of MgAl2O4 spinel from first principles |
| title_short | Disordering of MgAl2O4 spinel from first principles |
| title_sort | disordering of mgal2o4 spinel from first principles |
| work_keys_str_mv | AT warrenm disorderingofmgal2o4spinelfromfirstprinciples AT dovem disorderingofmgal2o4spinelfromfirstprinciples AT redferns disorderingofmgal2o4spinelfromfirstprinciples |