中性子回折実験で探る高温高圧下でのSiを含んだhcp鉄の水素化挙動

Abstract

The identification of light elements in the Earth's core has been an open question for more than 50 years. From seismic observation, the Earth’s core is believed to contain some light elements because it is about 10% less dense than pure Fe at the corresponding pressure and temperature conditions. Among the candidates of light elements in the core, hydrogen is one of the promising light elements. Neutron diffraction is very useful in systems when detecting light atoms surrounded by heavy atoms because its scattering intensity is independent of atomic number. Hence, many neutron diffraction studies have been performed on the iron-hydrogen binary system. On the other hand, it is likely that there is more than one type of light elements dissolved in the core, and interactions between light elements are also involved. Here, we focused on an Fe-Si-H system, and we investigated the sites occupied by deuterium and its site occupancy of hcp Fe0.95Si0.05 Hx at 14.7 GPa and 800 K by in-situ neutron diffraction experiments. So far, this pressure condition is the highest for neutron diffraction experiments at high pressure and high temperature, where crystal structure analysis has been conducted.