[S-IT17] Property and role of liquids inside terrestrial planets

[SIT17-04] Density and thermal expansion of liquid and solid iron at 1 atm determined using high-temperature furnace

★Invited Papers

*Hidenori Terasaki¹, Asaka Kamiya², Tadashi Kondo² (1.Department of Earth science, Okayama University, 2.Department of Earth and Space science, Osaka University)

Keywords:density, thermal expansion, iron, liquid

To estimate the structure and composition of a planetary core, the equation of state of iron alloys is an important information, along with planetary exploration data. The density and thermal expansion coefficient is one of the most fundamental characteristics to describe the equation of state. In this study, we precisely measured the densities of solid and liquid iron at high temperatures and ambient pressure using a high-temperature furnace with optical windows. The sample volume was determined from the optical image measured at each temperature. The density error of solid Fe was estimated to 0.11–0.7% in the temperature range of 295–1803 K with increments of 1–10 K. The two discontinuous density jumps were observed at 1162 and 1666 K which were derived from phase transitions (alpha/gamma/delta phases). The density decreased linearly with increasing temperature in each phase. For liquid, the density of liquid Fe was determined with uncertainty of 0.4–0.7% in the range of 1818–1998 K with temperature increments of 5 K. The obtained thermal expansion coefficient of liquid iron was 2.42(1) x 10^-4 K^-1.