Prediction of superconductivity in pressure-induced new silicon boride phases
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2020-01-27 |
| Journal | Physical review. B./Physical review. B |
| Authors | Xiaowei Liang, Aitor Bergara, Yu Xie, Linyan Wang, Rongxin Sun |
| Institutions | Jilin University, State Key Laboratory of Superhard Materials |
| Citations | 18 |
Abstract
Section titled āAbstractāThe crystal structures and properties of boron-silicon (B-Si) compounds under pressure have been systematically explored using particle swarm optimization structure prediction method in combination with first-principles calculations. Three new stoichiometries, B2Si, BSi, and BSi2, are predicted to be stable gradually under pressure, where increasing pressure favors the formation of silicon rich B-Si compounds. In the boron-rich compounds, the network of boron atoms changes from B12 icosahedron in the ambient phases to the similar buckled graphenelike layers in the high-pressure phases, which crystalize in the same PĀÆ3m1 symmetry but with different numbers of boron layers between adjacent silicon layers. Phonon calculations show that these structures might be retained to ambient conditions as metastable phases. Further electron-phonon coupling calculations indicate that the high-pressure phases of boron-rich compounds might superconduct at 1 atm, with the highest Tc value of 21 K from the Allen-Dynes equation in PĀÆ3m1 B2Si, which is much higher than the one observed in boron doped diamond-type silicon. Moreover, further fully anisotropic Migdal-Eliashberg calculations indicate that B2Si is a two-gap anisotropic superconductor and the estimated Tc might reach up to 30 K at 1 atm. On the silicon-rich side, BSi2 is predicted to be stable in the CuAl2-type structure. Our current results significantly enrich the phase diagram of the B-Si system and will stimulate further experimental study.