{"title":"氧化镁在液态铁中的混溶性","authors":"Leslie Insixiengmay, Lars Stixrude","doi":"arxiv-2409.07681","DOIUrl":null,"url":null,"abstract":"We explore phase equilbria on the MgO-Fe join as a prototype of\nlithophile-core interaction in terrestrial planets. Our simulations, based on\ndensity functional theory, are based on a two-phase method: fluids of initially\npure MgO and Fe compositions are allowed to establish a dynamic equilbrium\nacross a near-planar interface. Methods for analyzing the composition and other\nproperties of the two coexisting phases show that MgO behaves as a component,\nwith indistinguishable Mg and O concentrations in Fe-rich and oxide-rich\nphases. The phase diagram is well described as that of a symmetric regular\nsolution, a picture confirmed by independent one-phase determinations of the\nenthalpy, entropy, and volume of mixing. The critical temperature, above which\nthere is complete miscibility across the MgO-Fe join is 7000 K at 68 GPa, and\n9000 K and 172 GPa. The rate of MgO exsolution from the Fe-rich liquid on\ncooling is similar to that found in previous experimental studies, and is too\nsmall to drive a dynamo.","PeriodicalId":501270,"journal":{"name":"arXiv - PHYS - Geophysics","volume":"2 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"MgO Miscibility in Liquid Iron\",\"authors\":\"Leslie Insixiengmay, Lars Stixrude\",\"doi\":\"arxiv-2409.07681\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We explore phase equilbria on the MgO-Fe join as a prototype of\\nlithophile-core interaction in terrestrial planets. Our simulations, based on\\ndensity functional theory, are based on a two-phase method: fluids of initially\\npure MgO and Fe compositions are allowed to establish a dynamic equilbrium\\nacross a near-planar interface. Methods for analyzing the composition and other\\nproperties of the two coexisting phases show that MgO behaves as a component,\\nwith indistinguishable Mg and O concentrations in Fe-rich and oxide-rich\\nphases. The phase diagram is well described as that of a symmetric regular\\nsolution, a picture confirmed by independent one-phase determinations of the\\nenthalpy, entropy, and volume of mixing. The critical temperature, above which\\nthere is complete miscibility across the MgO-Fe join is 7000 K at 68 GPa, and\\n9000 K and 172 GPa. The rate of MgO exsolution from the Fe-rich liquid on\\ncooling is similar to that found in previous experimental studies, and is too\\nsmall to drive a dynamo.\",\"PeriodicalId\":501270,\"journal\":{\"name\":\"arXiv - PHYS - Geophysics\",\"volume\":\"2 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-09-12\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv - PHYS - Geophysics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/arxiv-2409.07681\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Geophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.07681","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
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.