First-principles comprehensive study of electronic and mechanical properties of novel uranium hydrides at different pressures

Highlights

• In a pressure up to 300 GPa twenty uranium hydrides have been predicted.

• Seven new uranium hydrides have never been reported previously.

• Their electronic, chemical bonding and mechanical properties have been analyzed.

Abstract

The systematic investigation on the U–H binary system up to 300 GPa has been performed by means of first-principles calculations in combination with the variable-composition evolutionary algorithm. Twenty uranium hydrides, including UH_x (x = 1, 2, 3, 4, 5, 6, 7, 8, 9, 17), U₂H_y (y = 3, 5, 7, 13, 15, 17), U₃H₈, U₃H₁₀, U₄H₅ and U₄H₉ have been found under different pressures. Besides thirteen compounds that are in nice agreement with previously reported structural search, new uranium hydrides in terms of the derived convex hull of the formation enthalpies have also been found in the present investigation. These seven novel compounds including Cmcm-UH₃, Fmmm-UH₄, R$\bar{3}$m-U₂H₇, Pm–U₂H₁₅, Cm–U₃H₈, C2–U₄H₉ and C2/m-U₄H₅, are found to be dynamically and thermodynamically stable, and their stable pressure range has been determined. At last, the electronic and mechanical properties of these seven novel structures have further been calculated.