[SIT20-P01] Melting relations in the Fe-P system at high pressures
Keywords:Earth's core, Core light element, Melting relations, High pressure
The melting relation was determined from in-situ X-ray diffraction measurements at the beamline BL10XU of the SPring-8 synchrotron facility. During heating, we observed a peritectic melting of Fe3P to liquid + Fe2P and complete melting up to 60 GPa. The onset and complete melting of the sample were judged from the intensity of diffuse scattering signals from the liquid. This melting phase relation was also confirmed from the chemical analysis on some recovered samples. Above 60 GPa, we observed the change in diffraction pattern of the Fe3P sample at subsolidus temperature conditions, which might be the decomposition to iron-rich and Fe2P phases. For this two-phase mixture, we also determined the solidus and liquidus temperatures. In the present experimental pressure conditions, the peritectic (or solidus) and liquidus temperatures of the Fe3P composition are ~700 K and ~200-300 K lower, respectively, relative to the melting temperature of Fe . These indicate that phosphorous reduces strongly the melting temperature of Fe.
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