We report a novel high-pressure cubic cF24 phase of TaSi₂ which is stable above 185 GPa through first-principles swarm intelligence structure search method. Results on enthalpy difference show that the structural transition of TaSi₂ from the ambient hexagonal C40 phase to cF24 phase is first order with a volume drop of 4.1%. Under compression, the formation of cubic cF24 phase originates from the dramatic polymerization of one dimensional helical Si chain in the low-pressure C40 phase creating peculiar 3D Si tetrahedrons framework embedded in diamond-like Ta sublattice. The emergence of 3D Si tetrahedrons framework in cF24 phase are suggested to be the main causes for its weaker metallic nature compared to the hexagonal C40 phase.

我们通过第一原理群智能结构搜索方法报告了一种新型的TaSi ₂高压立方cF 24相，该相稳定在185 GPa以上。焓差的结果表明，TaSi ₂从周围的六边形C 40相到cF 24相的结构转变是一级的，体积减小了4.1％。在压缩下，立方cF 24相的形成源自低压C 40相中一维螺旋Si链的剧烈聚合，从而形成了嵌在类金刚石Ta亚晶格中的独特3D Si四面体骨架。cF中3D Si四面体框架的出现与六方碳40相相比，认为24相是其金属性质较弱的主要原因。