Ab Initio Calculation Principles Study of Crystal Structure and Superconducting Properties of Y-Si-H System under High Pressure.

MA Hao; CHEN Ling; JIANG Qiwen; AN Decheng; DUAN Defang

Using first principles density functional theory calculations, the crystal structure, electronic properties, and superconductivity characteristics of the ternary hydride Y-Si-H system under high pressure were investigated. The study revealed the existence of thermodynamically stable phases, including YSiH7, YSiH9, YSi2H12, and YSiH18, and thermodynamically metastable phases, namely YSi2H13, YSi2H14, and Y2SiH17. Electronic properties calculations showed that YSiH7 is insulator and YSi2H13 is semiconductor, while the remaining hydrides exhibit metallic properties. Superconducting transition temperatures (Tc) were estimated using the McMillan equation, with YSi2H12 hosting the highest Tc of 43.5 K at 100 GPa. The dynamic stable pressure of YSi2H14 can be reduced to 40 GPa, and its Tc is 23.8 K which is twice the highest Tc among binary Y-Si compounds, indicating that introducing H atom into Y-Si system can effectively increase the superconducting transition temperature. Y2SiH17 exhibits a Tc of 35.8 K at 100 GPa. Spectral function and electron-phonon coupling calculations suggested that in YSi2H14 and Y2SiH17, in addition to the H-induced superconductivity from mid-frequency vibrations, low-frequency vibrations of Y also play a significant role for superconductivity.

AB-initio calculations; SUPERCONDUCTING transition temperature; CRYSTAL structure; ELECTRON-phonon interactions; DENSITY functional theory; SUPERCONDUCTIVITY

Chinese Journal of High Pressure Physics, 2024, Vol 38, Issue 2, p1

1000-5773

Academic Journal

10.11858/gywlxb.20230791