An X-Ray Absorption Spectroscopy Investigation into the Fundamental Structure of Liquid Metal Alloys.

Gallium and gallium alloys have gained significant interest due to gallium's low melting point. This property allows for gallium-based catalysts to take advantage of the unique reaction environments only available in the liquid state. While understanding of the catalytic properties of liquid metals is emerging, a comprehensive investigation into the fundamental structures of these materials has yet to be undertaken. Herein, the structure of liquid gallium, along with related liquid alloys EGaIn, EGaSn, and Galinstan are explored using X-ray absorption spectroscopy (XAS). In contrast to some other studies that show dimers, analysis of the XAS data both in X-ray absorption near edge structure and extended X-ray absorption fine structure shows that when fully dissolved the materials are largely homogenous with no obvious signs of local structures. Ga shows a bond contraction when melted which is consistent with its increase in density; however, an expansion in bond length is observed when alloyed with In and Sn. XAS data indicate that the effective nuclear charge ( ) of In and Sn follows the trend expected based on electronegativity. Molecular dynamic (MD) simulations are performed to simulate the structure and trends between MD and XAS; the trends agree well but MD overestimates bond lengths.