MgO Miscibility in Liquid Iron
Fuente:
arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866917774606991360 |
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| author | Insixiengmay, Leslie Stixrude, Lars |
| author_facet | Insixiengmay, Leslie Stixrude, Lars |
| contents | We explore phase equilbria on the MgO-Fe join as a prototype of lithophile-core interaction in terrestrial planets. Our simulations, based on density functional theory, are based on a two-phase method: fluids of initially pure MgO and Fe compositions are allowed to establish a dynamic equilbrium across a near-planar interface. Methods for analyzing the composition and other properties of the two coexisting phases show that MgO behaves as a component, with indistinguishable Mg and O concentrations in Fe-rich and oxide-rich phases. The phase diagram is well described as that of a symmetric regular solution, a picture confirmed by independent one-phase determinations of the enthalpy, entropy, and volume of mixing. The critical temperature, above which there is complete miscibility across the MgO-Fe join is 7000 K at 68 GPa, and 9000 K and 172 GPa. The rate of MgO exsolution from the Fe-rich liquid on cooling is similar to that found in previous experimental studies, and is too small to drive a dynamo. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_07681 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | MgO Miscibility in Liquid Iron Insixiengmay, Leslie Stixrude, Lars Geophysics We explore phase equilbria on the MgO-Fe join as a prototype of lithophile-core interaction in terrestrial planets. Our simulations, based on density functional theory, are based on a two-phase method: fluids of initially pure MgO and Fe compositions are allowed to establish a dynamic equilbrium across a near-planar interface. Methods for analyzing the composition and other properties of the two coexisting phases show that MgO behaves as a component, with indistinguishable Mg and O concentrations in Fe-rich and oxide-rich phases. The phase diagram is well described as that of a symmetric regular solution, a picture confirmed by independent one-phase determinations of the enthalpy, entropy, and volume of mixing. The critical temperature, above which there is complete miscibility across the MgO-Fe join is 7000 K at 68 GPa, and 9000 K and 172 GPa. The rate of MgO exsolution from the Fe-rich liquid on cooling is similar to that found in previous experimental studies, and is too small to drive a dynamo. |
| title | MgO Miscibility in Liquid Iron |
| topic | Geophysics |
| url | https://arxiv.org/abs/2409.07681 |