Pressure-induced electride phase formation in calcium: A key to its strange high-pressure behavior

Article

关键词: TOTAL-ENERGY CALCULATIONS;    CA;    TEMPERATURE;    TRANSITIONS;    RESISTANCE;    DYNAMICS;    NITRIDE;    SOLIDS;    METALS;    ANIONS;   

DOI  :  10.1103/PhysRevB.107.125152

来源: SCIE

【 摘 要 】

Elemental calcium (Ca), a simple metal at ambient conditions, has attracted huge interest because of its unusual high-pressure behavior in structural, electrical, and melting properties whose origins remain unsolved. Here, using a theoretical framework appropriate for describing electride phase formation, i.e., the presence of anionic electrons, we establish electride formation in Ca at a pressure as low as 8 GPa. Our analysis shows that under pressure the valence electrons of Ca localize at octahedral holes and exhibit anionic character which is re-sponsible for its strange pressure behavior. Our calculated enthalpy and electrical resistance indicate that Ca will directly transform from an fcc-electride phase to a simple cubic sc-electride phase near 30 GPa, thereby avoiding the intermediate bcc phase. These findings are not limited to Ca but might hold a key to the understanding of host-guest type structures which occur in other elemental solids, though at much higher pressures.

【 授权许可】

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