Iordanidis Lykourgos, Bilc Daniel, Mahanti Subhendra D, Kanatzidis Mercouri G
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
J Am Chem Soc. 2003 Nov 12;125(45):13741-52. doi: 10.1021/ja034196p.
An outstanding example of structural diversity and complexity is found in the compounds with the general formula ABi(3)Q(5) (A = alkali metal; Q = chalcogen). gamma-RbBi(3)S(5) (I), alpha-RbBi(3)Se(5) (II), beta-RbBi(3)Se(5) (III), gamma-RbBi(3)Se(5) (IV), CsBi(3)Se(5) (V), RbBi(3)Se(4)Te (VI), and RbBi(3)Se(3)Te(2) (VII) were synthesized from A(2)Q (A = Rb, Cs; Q = S, Se) and Bi(2)Q(3) (Q = S, Se or Te) at temperatures above 650 degrees C using appropriate reaction protocols. gamma-RbBi(3)S(5) and alpha-RbBi(3)Se(5) have three-dimensional tunnel structures while the rest of the compounds have lamellar structures. gamma-RbBi(3)S(5), gamma-RbBi(3)Se(5), and its isostructural analogues RbBi(3)Se(4)Te and RbBi(3)Se(3)Te(2) crystallize in the orthorhombic space group Pnma with a = 11.744(2) A, b = 4.0519(5) A, c = 21.081(3) A, R1 = 2.9%, wR2 = 6.3% for (I), a = 21.956(7) A, b = 4.136(2) A, c = 12.357(4) A, R1 = 6.2%, wR2 = 13.5% for (IV), and a = 22.018(3) A, b = 4.2217(6) A, c = 12.614(2) A, R1 = 6.2%, wR2 = 10.3% for (VI). gamma-RbBi(3)S(5) has a three-dimensional tunnel structure that differs from the Se analogues. alpha-RbBi(3)Se(5) crystallizes in the monoclinic space group C2/m with a = 36.779(4) A, b = 4.1480(5) A, c = 25.363(3) A, beta = 120.403(2) degrees, R1 = 4.9%, wR2 = 9.9%. beta-RbBi(3)Se(5) and isostructural CsBi(3)Se(5) adopt the space group P2(1)/m with a = 13.537(2) A, b = 4.1431(6) A, c = 21.545(3) A, beta = 91.297(3) degrees, R1 = 4.9%, wR2 = 11.0% for (III) and a = 13.603(3) A, b = 4.1502(8) A, c = 21.639(4) A, beta = 91.435(3) degrees, R1 = 6.1%, wR2 = 13.4% for (V). alpha-RbBi(3)Se(5) is also three-dimensional, whereas beta-RbBi(3)Se(5) and CsBi(3)Se(5) have stepped layers with alkali metal ions found disordered in several trigonal prismatic sites between the layers. In gamma-RbBi(3)Se(5) and RbBi(3)Se(4)Te, the layers consist of Bi(2)Te(3)-type fragments, which are connected in a stepwise manner. In the mixed Se/Te analogue, the Te occupies the chalcogen sites that are on the "surface" of the layers. All compounds are narrow band-gap semiconductors with optical band gaps ranging 0.4-1.0 eV. The thermal stability of all phases was studied, and it was determined that gamma-RbBi(3)Se(5) is more stable than the and alpha- and beta-forms. Electronic band calculations at the density functional theory (DFT) level performed on alpha-, beta-, and gamma-RbBi(3)Se(5) support the presence of indirect band gaps and were used to assess their relative thermodynamic stability.
通式为ABi(3)Q(5)（A = 碱金属；Q = 硫族元素）的化合物展现出了结构多样性和复杂性的一个突出例子。γ-RbBi(3)S(5)（I）、α-RbBi(3)Se(5)（II）、β-RbBi(3)Se(5)（III）、γ-RbBi(3)Se(5)（IV）、CsBi(3)Se(5)（V）、RbBi(3)Se(4)Te（VI）和RbBi(3)Se(3)Te(2)（VII）是通过在650摄氏度以上的温度下，使用适当的反应方案，由A(2)Q（A = Rb、Cs；Q = S、Se）和Bi(2)Q(3)（Q = S、Se或Te）合成的。γ-RbBi(3)S(5)和α-RbBi(3)Se(5)具有三维隧道结构，而其余化合物具有层状结构。γ-RbBi(3)S(5)、γ-RbBi(3)Se(5)及其同构类似物RbBi(3)Se(4)Te和RbBi(3)Se(3)Te(2)在正交空间群Pnma中结晶，对于（I），a = 11.744(2) Å，b = 4.0519(5) Å，c = 21.081(3) Å，R1 = 2.9%，wR2 = 6.3%；对于（IV），a = 21.956(7) Å，b = 4.136(2) Å，c = 12.357(4) Å，R1 = 6.2%，wR2 = 13.5%；对于（VI），a = 22.018(3) Å，b = 4.2217(6) Å，c = 12.614(2) Å，R1 = 6.2%，wR2 = 10.3%。γ-RbBi(3)S(5)具有与硒类似物不同的三维隧道结构。α-RbBi(3)Se(5)在单斜空间群C2/m中结晶，a = 36.779(4) Å，b = 4.1480(5) Å，c = 25.363(3) Å，β = 120.403(2)°，R1 = 4.9%，wR2 = 9.9%。β-RbBi(3)Se(5)和同构的CsBi(3)Se(5)采用空间群P2(1)/m，对于（III），a = 13.537(2) Å，b = 4.1431(6) Å，c = 21.545(3) Å，β = 91.297(3)°，R1 = 4.9%，wR2 = 11.0%；对于（V），a = 13.603(3) Å，b = 4.1502(8) Å，c = 21.639(4) Å，β = 91.435(3)°，R1 = 6.1%，wR2 = 13.4%。α-RbBi(3)Se(5)也是三维的，而β-RbBi(3)Se(5)和CsBi(3)Se(5)具有阶梯状层，其中碱金属离子在层间的几个三角棱柱位点无序分布。在γ-RbBi(3)Se(5)和RbBi(3)Se(4)Te中，层由Bi(2)Te(3)型片段组成，这些片段以逐步方式连接。在混合的Se/Te类似物中，Te占据层“表面”上的硫族元素位点。所有化合物都是窄带隙半导体，光学带隙范围为0.4 - 1.0 eV。研究了所有相的热稳定性，确定γ-RbBi(3)Se(5)比α-和β-形式更稳定。在密度泛函理论（DFT）水平上对α-、β-和γ-RbBi(3)Se(5)进行的电子能带计算支持间接带隙的存在，并用于评估它们的相对热力学稳定性。
