Synthesis of Xenon and Iron/Nickel intermetallic compounds at Earth's core thermodynamic conditions

TL;DR

This study demonstrates the formation of stable xenon-iron and xenon-nickel compounds under Earth's core conditions, providing insights into noble gas chemistry and potential explanations for the missing xenon paradox.

Contribution

It provides the first experimental evidence of stable Xe-Fe/Ni compounds at high pressures, combining in situ spectroscopy with first principles calculations.

Findings

Stable Xe(Fe,Fe/Ni)$_3$ and XeNi$_3$ compounds synthesized

Noble gases can form stable compounds with electropositive elements at high pressures

Results shed light on noble gas chemistry under extreme conditions

Abstract

Although Xe is known to form stable compounds with strong electronegative elements, evidence on the formation of stable compounds with electropositive elements, such as Fe and Ni, was missing until very recently. In addition to the significance of the emerging field of noble gas elements chemistry, the possible formation of Xe-Fe/Ni compounds has been proposed as a plausible explanation of the so-called "missing Xe paradox". Here we explore the possible formation of stable compounds in the Xe-Fe/Ni systems at thermodynamic conditions representative of Earth's core. Using in situ synchrotron X-ray diffraction and Raman spectroscopy in concert with first principles calculations we demonstrate the synthesis of stable Xe(Fe,Fe/Ni)$_3$ and XeNi$_3$ compounds. The results indicate the changing chemical properties of elements under extreme conditions where noble gas elements can form stable compounds with elements which are electropositive at ambient conditions but become slightly electronegative at high pressures.