<br/>High pressure is able to modify profoundly the chemica l bonding and generate new phase structures of materials with  chemical and physical properties not accessibleat ambient conditions. We here report an unprecedented phenomenon on the pressure-induced formation of semi-conducting 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 structure for Ca2N and a monoclinic Cc structure shared by Sr2N and Ba2N, both of which contain atomic-size cavities with paring electronsdistributed 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.

Pressure-stabilized semiconducting electrides in alkaline-earth- metal subnitrides

256th National Meeting (2018)

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