LINK<\/strong><\/a><\/p>\n\n\n\n“Highlights<\/p>\n\n\n\n
\u2022 The activity coefficient of FeO decreases with decreasing oxygen fugacity.
\n\u2022 Silicon in metal decreases activities of trace elements in Fe-rich alloys.
\n\u2022 Interaction coefficients of trace elements in FeSi alloys vary with pressure.”<\/p>\n\n\n\n
“The differences in FeO mantle contents and core masses between the terrestrial planets suggest the oxygen fugacity (fO2) during their differentiation likely varied significantly. The metal-silicate partitioning of siderophile (iron-loving) elements is a function of fO2 and of their valence state(s) in silicate melts. Silicon (Si) is known to partition into metal at low fO2 and has been proposed as a possible light element in the cores of Mercury and the aubrite parent body (AuPB).<\/p>\n\n\n\n
To systematically study the metal-silicate partitioning behavior of siderophile elements into Si-bearing metal, 69 high pressure (P) \u2013 temperature (T) metal-silicate partitioning experiments were performed under moderately to highly reducing conditions. Oxygen fugacities ranged between 1 and 7\u202funits below the iron-w\u00fcstite buffer (\u0394IW). Experimental pressures and temperatures ranged between 1 and 5\u202fGPa and 1883 to 2273\u202fK, respectively. A comparison of the \u0394IW values and the fO2 based on the Si-SiO2 buffer (\u0394Si-SiO2) indicates that the activity coefficient of FeO in silicate melts decreases significantly from reducing to highly reducing conditions under C-saturated conditions. It was found that at conditions more reducing than \u0394IW\u202f=\u202f\u22123 to \u22124, the metal-silicate partitioning behavior of the majority of the siderophile elements deviates significantly from values corresponding to their expected valence state(s). These results indicate that the activity in metal of the elements considered, including that of Si itself, is decreased as a function of Si metal content, and a thermodynamic approach was used to quantify these effects. Interaction coefficients of trace elements in Si-bearing, Fe-rich alloys (\u03b5MSi) derived from the new experiments are in good agreement with previously proposed values at similar pressures below 5\u202fGPa. However, \u03b5MSi values obtained for C-free systems decrease within the 1 to 11\u202fGPa range, suggesting extrapolation of lower-pressure parameters may yield erroneous results at much higher pressures. Altogether, the new results provide an extensive experimental foundation for future studies of planetary differentiation under (highly) reduced conditions.”<\/p>\n","protected":false},"excerpt":{"rendered":"
E.S. Steenstra, A.X. Seegers, R. Putter, J. Berndt, S. Klemme, S. Matveev, E. Bullock, W. van Westrenen Icarus LINK “Highlights \u2022 The activity coefficient of FeO decreases with decreasing oxygen fugacity. \u2022 Silicon in metal…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[38,75,1183,137,73],"tags":[1852,1657,2587,1970,1592],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20207"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=20207"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20207\/revisions"}],"predecessor-version":[{"id":20208,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20207\/revisions\/20208"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=20207"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=20207"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=20207"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}