Mg2IrH6 is a metastable complex metal hydride with a predicted superconducting transition temperature as high as 170 K at ambient pressure. Following the synthesis of isomorphic, insulating Mg2IrH5 at low pressure, higher-pressure studies were conducted to investigate the phase behavior and compound formation in this system. X-ray diffraction and Raman spectroscopic measurements indicate that cubic Mg2IrH7 is stabilized above ca. 40 GPa and coexists with a related hexagonal hydride with likely composition near Mg2IrH5. Electrical transport measurements show that the cubic Mg2IrH7 is insulating, in agreement with ab initio predictions, and persists during room-temperature decompression until ∼20 GPa before reverting back to the cubic Mg2IrH5. The experimental results confirm ground-state structure predictions in the Mg-Ir-H system, and the formation of two nearly identical phases with surrounding compositions opens new opportunities to access superconducting Mg2IrH6 through non-equilibrium processing pathways.
@article{arxiv.2602.23675,
title = {High-pressure stabilization of Mg2IrH7: Structural proximity to high-Tc superconductivity},
author = {Shubham Sinha and Wencheng Lu and Mads F. Hansen and Michael J. Hutcheon and Trevor W. Bontke and Lewis J. Conway and Kapildeb Dolui and Chris J. Pickard and Christoph Heil and Piotr A. Guńka and Stella Chariton and Vitali Prakapenka and Liangzi Deng and Ching-Wu Chu and Matthew N. Julian and Rohit P. Prasankumar and Timothy A. Strobel},
journal= {arXiv preprint arXiv:2602.23675},
year = {2026}
}