Department of Applied Chemistry, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan.
Inorg Chem. 2012 Dec 17;51(24):13328-33. doi: 10.1021/ic302027b. Epub 2012 Dec 3.
New multinary selenides Ae3SnPn2Se8 (Ae = Sr, Ba; Pn = Sb, Bi), Sr8.01Ge2.04Bi7.95Se24, and Sr8YGe2Bi7Se24 were synthesized by solid-state reaction, and their structures were determined by single-crystal X-ray diffraction. These compounds crystallize in orthorhombic space group Pnma (no. 62) for Ae3SnPn2Se8 (Ae = Sr, Ba; Pn = Sb, Bi) and in Pna21 (no. 33) for Sr8.01Ge2.04Bi7.95Se24 and Sr8YGe2Bi7Se24. The structures feature one-dimensional corner sharing tetrahedral (∞)(1)[MSe3] units, and one-dimensional edge sharing octahedral ∞1[M4Se10], packed with the alkaline earth or rare earth cations. Sr8.01Ge2.04Bi7.95Se24 and Sr8YGe2Bi7Se24 contain a triple cell superlattice structure derived from a special arrangement of Bi and Ge in the tetrahedrally coordinated ∞1[MSe3] chain. Diffuse reflectance spectra and electronic resistivity measurements indicate semiconducting behaviors; the Sr8YGe2Bi7Se24 Seebeck coefficient is −180 μV/K at 303 K. Electronic structure calculations confirm that the electron count for Sr8YGe2Bi7Se24 is optimal for interatomic bonding in the ionic network.
新型多主族硒化物 Ae3SnPn2Se8（Ae=Sr，Ba；Pn=Sb，Bi）、Sr8.01Ge2.04Bi7.95Se24 和 Sr8YGe2Bi7Se24 通过固态反应合成，并通过单晶 X 射线衍射确定其结构。这些化合物在正交晶系 Pnma（No.62）中结晶为 Ae3SnPn2Se8（Ae=Sr，Ba；Pn=Sb，Bi），在 Pna21（No.33）中结晶为 Sr8.01Ge2.04Bi7.95Se24 和 Sr8YGe2Bi7Se24。结构特征为一维顶角共享四面体（∞）（1）[MSe3]单元，一维边缘共享八面体∞1[M4Se10]，与碱土或稀土阳离子堆积。Sr8.01Ge2.04Bi7.95Se24 和 Sr8YGe2Bi7Se24 包含源自 Bi 和 Ge 在四面体配位∞1[MSe3]链中的特殊排列的三重胞超晶格结构。漫反射光谱和电子电阻率测量表明具有半导体行为；Sr8YGe2Bi7Se24 在 303 K 时的 Seebeck 系数为-180 μV/K。电子结构计算证实，Sr8YGe2Bi7Se24 的电子计数对于离子网络中原子间键合是最佳的。
