Theoretical Prediction And Physical Properties Of New Uranium-hydrogen Compounds Under High Pressure

Hydride materials have fascinating physical and chemical properties such as various structures and superconducting at high pressures.People have been focusing on the exploration of high-temperature superconducting materials.Recently,scientists have discovered in the experiment the high-T_c of 203 K of the compressed H₂S at 155 GPa.Stable structures of uranium hydrides at 0-550 GPa were studied using genetic algorithm?GA?combined with density functional theory?DFT?calculations.We investigated structures of UH₄,UH₈ and UH₁₀0 at high pressures,and properties,including stability,electronic property and superconductivity.1.Our study found that UH₈ was the most stable phase at 100-550 GPa.UH₄ was a stable phase at 100-550 GPa.It had a phase transition from Cmca to R3m at 180 GPa and R3m to C2/m at 370 GPa.And UH₁₀0 could become stable over 450 GPa.For UH₁₀,the most stable phase was Fm3 m.By comparing with the enthalpy values of UH₅ and UH₇,it was found that UH₅ was most stable at 10-20 GPa,UH₇ was most stable at 25-50 GPa.2.Under high pressures,Cmca-UH₄,R3m-UH₄,C2/m-UH₄,Fm 3 m-UH₈ and Fm 3 m-UH₁₀0 all showed metallic properties,but only Fm 3 m-UH₁₀0 showed superconductivity and the T_c's of the Fm 3 m-UH₁₀0 structure were predicted to be 51,21,12,10 and 15 K at 100,200,300,400 and 550 GPa,respectively.