Experimental and DFT computational study on hexaaquamagnesium(II) acesulfamate

Abstract

Poster Sessions C684 metal-hydrogen systems. To study structure of liquid transition metal hydrogen alloys, we have performed in-situ energy-dispersive x-ray diffraction measurements at high pressures and high temperatures using a cubic-type multi-anvil press on BL14B1 at SPring-8 synchrotron facility. Pure metal wire was used as a starting material and LiAlH 4 was used as a hydrogen source. The x-ray diffraction measurements on liquid pure metals were also performed for comparison. FeH x is one of the most studied hydrides under high pressure. A solubility of hydrogen in iron is small at ambient conditions but iron and hydrogen react under high pressure and FeH x (x≈0.8) is formed at 6.7GPa and 250°C [1]. The melting temperature of FeH x has been reported by several groups and it is lower than that of pure iron by 500°C at 5 GPa [2], [3]. Our X-ray measurements confirmed the hydrogenation of iron and the decrease of the melting temperature. The pair correlation functions, which are obtained by Fourier transformation of structure factor, indicate that the Fe-Fe nearest neighbor distance in FeH x is slightly longer than that in pure Fe [4]. Similar amount of elongations of the atomic distance were observed also in NiH x and CoH x. In spite of a suggestion of a large decrease of melting temperature in VH x [5], we have not observed melting transition in our X-ray measurements for VH x. We thank Y. Fukai for discussion.