碱土金属
单斜晶系
化学
化学物理
四方晶系
电子
环境压力
半导体
结晶学
相(物质)
土(古典元素)
金属
相变
过渡金属
电子能带结构
纳米技术
凝聚态物理
晶体结构
材料科学
热力学
光电子学
物理
量子力学
生物化学
催化作用
有机化学
数学物理
作者
Yunwei Zhang,Weikang Wu,Yanchao Wang,Shengyuan A. Yang,Yanming Ma
摘要
High pressure is able to modify profoundly the chemical bonding and generate new phase structures of materials with chemical and physical properties not accessible at ambient conditions. We here report an unprecedented phenomenon on the pressure-induced formation of semiconducting electrides via compression of layered alkaline-earth subnitrides Ca2N, Sr2N, and Ba2N that are conducting electrides with loosely confined electrons in the interlayer voids at ambient pressure. Our extensive first-principles swarm structure searches identified the high-pressure semiconducting electride phases of a tetragonal I4̅2d structure for Ca2N and a monoclinic Cc structure shared by Sr2N and Ba2N, both of which contain atomic-size cavities with paring electrons distributed within. These electride structures are validated by the excellent agreement between the simulated X-ray diffraction patterns and the experimental data available. We attribute the emergence of the semiconducting electride phases to the p–d hybridization on alkaline-earth-metal atoms under compression as well as the filling of the p–d hybridized band due to the interaction between Ca and N. Our work provides a unique example of pressure-induced metal-to-semiconductor transition in compound materials and reveals unambiguously the electron-confinement topology change between different types of electrides.
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