High‐Pressure Synthesis of Quantum‐Stabilised Manganese Superhydride MnH 7

Abstract

ABSTRACT Through high‐temperature, high‐pressure diamond anvil cell studies combined with in situ synchrotron powder x‐ray diffraction, we investigate the reactivity between manganese and hydrogen up to 182 GPa. Laser heating manganese in an medium at 118 GPa yields body‐centred tetragonal , which has the highest hydrogen content ever observed in the binary hydrides of group IV–XII transition metals. In addition, we also observe two other new hydrides as minor phases, with a tetragonal crystal structure and cubic , formed at the pressures of 105 and 118 GPa, respectively. Upon decompression, and remain stable down to 30 GPa before decomposing into the monohydride. Our ab initio quantum chemistry computations employing density‐functional theory reveal that the key stabilisation factor of and is zero‐point energy, however, no isotope effect is observed on the crystal structures of the deuterated samples.