Structural investigation of GeSb6Te10 and GeBi6Te10 intermetallic compounds in the chalcogenide homologous series.
Structural investigation of GeSb6Te10 and GeBi6Te10 intermetallic compounds in the chalcogenide homologous series.
复制标题
DOI：
10.1107/s0108768110024080
复制
发表时间：
2010-08
期刊：
影响因子：
--
通讯作者：
T. Matsunaga;R. Kojima;N. Yamada;Tomoko Fujita;K. Kifune;Y. Kubota;M. Takata
中科院分区：
文献类型：
--
作者：
T. Matsunaga;R. Kojima;N. Yamada;Tomoko Fujita;K. Kifune;Y. Kubota;M. Takata
使用X射线粉末衍射方法对GeSb(6)Te(10)和GeBi(6)Te(10)的晶体结构进行了检查，结果表明这些化合物结晶为具有51层周期（R3m）的三角扭曲立方密排结构。每层由三角形原子网组成； Te原子占据它们自己的特定层，而Ge、Sb和Bi原子位于其他层。在这些伪二元化合物中，观察到Ge和Sb/Bi的随机原子占据，并且层通过沿c轴连续堆叠形成两种元素结构块。可以推测这些化合物是同构的。已知这些伪二元体系中具有同系结构的硫族化合物的化学式可写为(GeTe)(n)(Sb(2)Te(3))(m)或(GeTe)(n)(Bi(2)Te(3))(m)(n、m：整数)；本研究中研究的GeSb(6)Te(10)和GeBi(6)Te(10)对应于n = 1和m = 3的情况，根据这些硫系化合物中常见的形成规则l = 2n + 5m（l代表基本结构单元中的层数），自然具有3 x l = 51层结构。基于密度泛函理论的计算表明，这些材料是带隙非常窄的化合物半导体。
The crystal structures of GeSb(6)Te(10) and GeBi(6)Te(10) were scrutinized using an X-ray powder diffraction method, which revealed that these compounds crystallize in trigonally distorted cubic close-packed structures with a 51-layer period (R3m). Each layer consists of a triangular atomic net; Te atoms occupy their own specific layers, whereas Ge, Sb and Bi atoms are located in the other layers. In these pseudobinary compounds, random atomic occupations of Ge and Sb/Bi are observed and the layers form two kinds of elemental structural blocks by their successive stacking along the c axis. These compounds can be presumed to be isostructural. It is known that the chemical formula of the chalcogenide compounds with the homologous structures found in these pseudobinary systems can be written as (GeTe)(n)(Sb(2)Te(3))(m) or (GeTe)(n)(Bi(2)Te(3))(m) (n, m: integer); the GeSb(6)Te(10) and GeBi(6)Te(10) investigated in this study, which correspond to the case in which n = 1 and m = 3, naturally have 3 x l = 51-layer structures according to a formation rule l = 2n + 5m commonly found in the compounds of these chalcogenide systems (l represents the number of layers in the basic structural unit). Calculations based on the density functional theory revealed that these materials are compound semiconductors with very narrow band gaps.