三元富氢高温超导体的理论设计与高压研究

高压下硫氢化物203K高温超导电性的新发现点燃了设计与合成氢基室温超导体的科学梦想。最近，一系列超导转变温度达到室温或超过冰点的笼型二元富氢化合物被理论预言，使笼型氢化物成为高压领域的研究热点。项目组通过对Li-Mg-H体系的初步探索发现，三元氢化物蕴藏着丰富的氢笼结构类型与潜在的室温超导体，其高压研究有望获得原始创新。本项目将聚焦于Li-M-H(M=Mg,Ca,Sc,Y)体系，探索其高压相晶体结构，构筑高压相图，获得三元笼型氢化物的稳定压力条件与可能的合成路径；研究其电子、晶格动力学及电子－声子相互作用性质，并通过求解能隙方程合理预测三元笼型氢化物具有室温超导电性的可能性；寻找三元笼型氢化物的结构特征与超导电性之间具有何种定性或定量的关联。本项目的实施可以为发现氢基室温超导体提供理论支撑。

The discovery of sulfur hydrides with Tc of 203K has aroused great interest in the rational design and synthesis of superhydrides with higher Tc at high pressure. Recently, the H-clathrate structure has been a hot topic in this field, since which was found to be a sign of the high-Tc superconductivity in several binary superhydrides. Our preliminary studies on Li-Mg-H alloys indicated that ternaries are as important as binaries for the design of H-clathrate structures, and the high-pressure studies on them would create breakthrough innovations. This research project focuses on the Li-M-H(M=Mg,Ca,Sc,Y) system, and the three major goals are as following: 1) to explore the crystal structure of the high-pressure polymorphs, build the high-pressure phase diagram, and obtain the pressure condition of stability and the possible synthesis routes; 2) to study the electronic property, lattice dynamics, electron-phonon couplings, and make a rational prediction on the room-temperature superconductivity of the predicted H clathrate ternaries based on the Tc solved from the gap equation, 3) to investigate the relationship between the superconductivity and the structural features of H clathrate structures. The present project is anticipated to provide theories to support the discovery of room-temperature superconductivity in superhydrides.