Fe-FeS eutectic temperatures to 620 kbar

Eutectic melting temperatures for the system Fe-FeS have been measured for the first time in the diamond anvil cell, using improved techniques to identify the solidus temperatures. Results at low pressure are in excellent agreement with previous measurements. The eutectic temperature increases linearly with pressure and remains lower than the melting temperatures of either Fe or FeS throughout the pressure range of this work. However, the magnitude of the eutectic depression becomes smaller at high pressure, in contrast to previous assumptions. These results support rather than exclude the possibility of solid-solution between iron and sulfide at core pressures, as suggested from electronic band structure calculations.