Hydrogen pentagraphenelike structure stabilized by hafnium : a high-temperature conventional superconductor

• Main Authors: Xie, Hui, Yao, Yansun, Feng, Xiaolei, Duan, Defang, Song, Hao, Zhang, Zihan, Jiang, Shuqing, Redfern, Simon Anthony Turner, Kresin, Vladimir Z., Pickard, Chris J., Cui, Tian
• Other Authors: Asian School of the Environment
• Format: Article
• Language: English
• Published: 2021
• Subjects: Science::General; Hafnium; Conventional Superconductor
• Online Access: https://hdl.handle.net/10356/146269
• Institution: Nanyang Technological University

The recent discovery of H_{3}S and LaH_{10} superconductors with record high superconducting transition temperatures T_{c} at high pressure has fueled the search for room-temperature superconductivity in the compressed superhydrides. Here we introduce a new class of high T_{c} hydrides with a novel structure and unusual properties. We predict the existence of an unprecedented hexagonal HfH_{10}, with remarkably high value of T_{c} (around 213-234 K) at 250 GPa. As concerns the novel structure, the H ions in HfH_{10} are arranged in clusters to form a planar "pentagraphenelike" sublattice. The layered arrangement of these planar units is entirely different from the covalent sixfold cubic structure in H_{3}S and clathratelike structure in LaH_{10}. The Hf atom acts as a precompressor and electron donor to the hydrogen sublattice. This pentagraphenelike H_{10} structure is also found in ZrH_{10}, ScH_{10}, and LuH_{10} at high pressure, each material showing a high T_{c} ranging from 134 to 220 K. Our study of dense superhydrides with pentagraphenelike layered structures opens the door to the exploration of a new class of high T_{c} superconductors.