Ternary arsenides A2Zn5As4 (A = K, Rb): zintl phases built from stellae quadrangulae.
Ternary arsenides A2Zn5As4 (A = K, Rb): zintl phases built from stellae quadrangulae.
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DOI：
10.1021/ic301311m
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发表时间：
2012-08
影响因子：
4.6
通讯作者：
S. Stoyko;M. Khatun;A. Mar
中科院分区：
文献类型：
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作者：
S. Stoyko;M. Khatun;A. Mar
元素在高温下化学计量反应生成K(2)Zn(5)As(4)（650℃）和Rb(2)Zn(5)As(4)（600℃）三元砷化物。K(2)Zn(5)As(4)采用新的结构类型(Pearson符号oC44，空间群Cmcm， Z = 4, a = 11.5758(5) Å， b = 7.0476(3) Å， c = 11.6352(5) Å；对于Rb(2)Zn(5)As(4), a = 11.6649(5) Å， b = 7.0953(3) Å， c = 11.7585(5) Å，具有连接ZnAs(4)四面体的复杂三维框架，产生由碱金属阳离子占据的大通道。描述结构的另一种有用的方法是通过使用星形四边形，每个四边形由四个ZnAs(4)四面体组成，覆盖一个空的中央四面体。这些化合物为Zintl相；对K(2)Zn(5)As(4)和Rb(2)Zn(5)As(4)的能带结构计算表明其具有半导体性质，直接带隙为0.4 eV。
Stoichiometric reaction of the elements at high temperature yields the ternary arsenides K(2)Zn(5)As(4) (650 °C) and Rb(2)Zn(5)As(4) (600 °C). They adopt a new structure type (Pearson symbol oC44, space group Cmcm, Z = 4; a = 11.5758(5) Å, b = 7.0476(3) Å, c = 11.6352(5) Å for K(2)Zn(5)As(4); a = 11.6649(5) Å, b = 7.0953(3) Å, c = 11.7585(5) Å for Rb(2)Zn(5)As(4)) with a complex three-dimensional framework of linked ZnAs(4) tetrahedra generating large channels that are occupied by the alkali-metal cations. An alternative and useful way of describing the structure is through the use of stellae quadrangulae each consisting of four ZnAs(4) tetrahedra capping an empty central tetrahedron. These compounds are Zintl phases; band structure calculations on K(2)Zn(5)As(4) and Rb(2)Zn(5)As(4) indicate semiconducting behavior with a direct band gap of 0.4 eV.