An experimental study of silver and palladium partitioning between solid and liquid metal,with applications to iron meteorites |
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| Authors: | NANCY L CHABOT MICHAEL J DRAKE |
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| Abstract: | Abstract— Solid metal/liquid metal partition coefficients for Ag and Pd were determined experimentally as a function of the S concentration of the metallic liquid. Silver is incompatible in solid metal and strongly sensitive to the S content of the metallic liquid; partition coefficients for Ag decrease more than an order of magnitude with increasing S content of the metallic liquid and can be expressed as:  where k(Ag) is the molar solid metal/liquid metal partition coefficient and XS is the molar S content of the metallic liquid. The partition coefficient of Pd is less variable but changes from modestly incompatible to modestly compatible in solid metal with increasing S content of the metallic liquid:  With these new partition coefficients for Pd and a fractional crystallization model, Pd abundance trends recorded in iron meteorite groups are modeled successfully. Measured Ag distribution between troilite-rich nodules and adjacent metal in iron meteorites also agree well with experimental solid metal/liquid metal equilibrium values. However, observed Pd metal/nodule distributions do not agree with experimentally determined partition coefficients, which suggests a more complex history than simple solid metal/liquid metal equilibrium. |
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