Browsing by Author "Yu, Ching-Yi"

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Synthesis and characterization of a new quaternary selenide Sr(3)GeSb(2)Se(8)
(2008-09-01)
Yu, Ching-Yi
;
Wang, Ming-Fang
;
Chung, Ming-Yang
;
Jang, Shyue-Ming
;
Huang, Jih-Chen
A new quaternary selenide Sr(3)GeSb(2)Se(8) has been synthesized at 750 degrees C from pure elements in a stoichiometric ratio under vacuum. The product as-synthesized is characterized by single-crystal X-ray diffraction, diffuse reflectance spectroscopy, and thermoanalysis. The title compound crystallizes in the orthorhombic space group Pnma with a = 12.633(4) angstrom, b = 4.301(1) angstrom, c = 28.693(7) angstrom, V = 1558.8(8) angstrom(3), Z = 4, R(1)/wR(2) = 0.0582/0.1221, and GOF = 1.077. The structure of Sr(3)GeSb(2)Se(8) features a new structural type that consists of one-dimensional chains of vertex-sharing tetrahedra (1)(infinity)[MSe(3)] (M = Ge/Sb) and fused double chains of edge-shared square pyramids (1)(infinity)[M(2)Se(5)], which are held together by Sr(2+) ions. A band gap of 0.75 eV for Sr(3)GeSb(2)Se(8) was derived from its diffuse reflectance spectrum. (C) 2007 Elsevier Masson SAS. All rights reserved.
Ternary Chalcogenides GeSb2Se3 and Ge3Sb4Se7 Containing a (1)(infinity)[Sb2Se2](2-) 1D Chain and a 2D Structure Related to SnSe
(2020-08-17)
Chen, Guan-Ruei
;
Li, Chien-He
;
Yu, Ching-Yi
;
Wang, Ming-Fang
;
Lee, Chi-Shen
Ternary chalcogenides, GeSb2Se3 and Ge3Sb4Se7, were synthesized and characterized. These chalcogenides are the first ternary selenides in a ternary Ge-Sb-Se system that feature a layer structure related to black phosphorus and SnSe-type structures. Both compounds contain a(infinity)( 1)[Sb2Se2](2-) unit with Sb+ cations in a zigzag Sb-Sb chain structure, and Sb3+ cations in a distorted NaCl100-type of (1)(infinity)[Gen-2Sb2Sen](2+) unit (n = 4, 5). These materials exhibit n-type semiconducting properties with thermal conductivity significantly lower than that of GeSe and Sb2Se3, which could be correlated to the 1D Sb+ chain and disordered sites with different Ge/Sb compositions. It is anticipated that these newly discovered ternary chalcogenides may provide unique properties with enhanced thermoelectric properties.