Novel Superconducting Electrides in Ca–S System under High Pressures

查看全文 作　　者：[1]刘云仙;[1]王超;[1]韩帅;[1]陈欣;[1]孙海瑞;[1]刘晓兵 机构地区：[1]Laboratory of High Pressure Physics and Material Science(HPPMS),School of Physics and Physical Engineering,Qufu Normal University,Qufu 273165,China 出　　处：《Chinese Physics Letters》索引2021年第38卷第3期,共6页 基　　金：Supported by the National Natural Science Foundation of China(Grant Nos.11704220,11804184,11974208 and 11804185);the Shandong Provincial Natural Science Foundation(Grant Nos.ZR2017BA020,ZR2018PA010,ZR2019MA054 and ZR2017BA012)。 摘　　要：Due to their unique structure properties,most of the electrides that possess extra electrons locating in interstitial regions as anions are insulators.Metallic and superconducting electrides are very rare under ambient conditions.We systematically search possible compounds in Ca-S systems stabilized under various pressures up to 200 GPa,and investigate their crystal structures and properties using first-principles calculations.We predict a series of novel stoichiometries in Ca-S systems as potential superconductors,including P2_(1)/m Ca_(3)S, Pnma Ca_(3)S,Pnma Ca_(2)S,Cmcm Ca_(2)S,Fddd CaS_(2),Immm CaS_(3) and C2/c CaS_(4).The P4mbm Ca_(3)S phase exhibits a maximum Tc value of ~20K.It is interesting to notice that the P2_(1)/m Ca_(3)S and Pnma Ca_(2)S stabilized at 60 and 50 GPa behave as superconducting electrides with critical temperatures Tc of 7.04 K and 0.26 K,respectively.More importantly,our results demonstrate that P2_(1)/m Ca_(3)S and Pnma Ca_(2)S are dynamically stable at 5 GPa and 0 GPa,respectively,indicating a high possibility to be quenched to ambient condition or synthesized using the large volume press. 关 键 词：AMBIENT STABILIZED locating