At Advanced Light Source (ALS) Beamline 12.2.2, researchers performed x-ray diffraction experiments on a nickel–argon mixture while subjecting it to pressures greater than 1.5 million times Earth’s atmospheric (surface) pressure and temperatures above 2000 K (1,700 C or 3,100F). The results strongly indicated that a new compound does indeed form—an alloy of 50% argon and 50% nickel. Theoretical calculations revealed that argon engages in significant electron transfer with nickel, resulting in a material with the crystal structure of an intermetallic alloy, with the argon and nickel equally interspersed in a solid solution. The results open up the possibility of argon being bound to nickel in the Earth’s core and may help solve outstanding geological questions about the location of argon (the “missing argon paradox”). Moreover, this study highlights that extreme pressures and temperatures lead to new chemistry rules and underscores the need for close synergy between experimental and theoretical studies in this new frontier of chemical properties under extreme thermodynamic conditions. Reference: “A High-Pressure Compound of Argon and Nickel: Noble Gas in the Earth’s Core?” by Adebayo A. Adeleke, Martin Kunz, Eran Greenberg, Vitali B. Prakapenka, Yansun Yao and Elissaios Stavrou, 1 October 2019, ACS Earth and Space Chemistry.DOI: 10.1021/acsearthspacechem.9b00212
