Synthesis and superconductivity in yttrium superhydrides under high pressure

• Published in: Chinese physics B 2022-09, Vol.31 (10), p.106201-123
• Main Authors: Wang, Yingying, Wang, Kui, Sun, Yao, Ma, Liang, Wang, Yanchao, Zou, Bo, Liu, Guangtao, Zhou, Mi, Wang, Hongbo
• Format: Article
• Language: English
• Subjects: high pressure; superconductivity; superhydride
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/ac872e

Flourishing rare earth superhydrides are a class of recently discovered materials that exhibit near-room-temperature superconductivity at high pressures, ushering in a new era of superconductivity research at high pressures. Yttrium superhydrides drew the most attention among these superhydrides due to their abundance of stoichiometries and excellent superconductivities. Here, we carried out a comprehensive study of yttrium superhydrides in a wide pressure range of 140 GPa–300 GPa. We successfully synthesized a series of superhydrides with the compositions of YH 4 , YH 6 , YH 7 , and YH 9 , and reported superconducting transition temperatures of 82 K at 167 GPa, 218 K at 165 GPa, 29 K at 162 GPa, and 230 K at 300 GPa, respectively, as evidenced by sharp drops in resistance. The structure and superconductivity of YH 4 were taken as a representative example and were also examined using x-ray diffraction measurements and the superconductivity suppression under external magnetic fields, respectively. Clathrate YH 10 , a candidate for room-temperature superconductor, was not synthesized within the study pressure and temperature ranges of up to 300 GPa and 2000 K. The current study established a detailed foundation for future research into room-temperature superconductors in polynary yttrium-based superhydrides.