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새로운 오성분계 황화물의 합성과 특징
- Alternative Title
- Eunsil Lee
- Author(s)
- 이은실
- Alternative Author(s)
- Eunsil Lee
- Advisor
- 윤호섭
- Department
- 일반대학원 에너지시스템학부
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2012-02
- Language
- eng
- Alternative Abstract
- New quintenary sulfides, ACuTiGe2S7 (A = Rb, Cs)와 Ax(Nb1-yTay)PS6 (A=K, Rb) have been prepared with the use of eutectic alkali metal halide fluxes (RbCl/LiCl or CsCl/LiCl) and their crystal structures have been investigated by single crystal X-ray diffraction techniques. I. ACuTiGe2S7 (A = Rb, Cs) ACuTiGe2S7 (A = Rb, Cs) are the first of the quintenary thiogermanates reported. The title compounds are isostructural and they crystallize in space group P of the triclinic system with two formula units in a cell dimensions: a = 7.0598(9) Å, b = 12.511(2) Å, c = 7.1441(8) Å, α = 75.906(4)˚, β = 79.101(4)˚, γ = 74.749(4)˚, V = 585.2(1) Å3 for RbCuTiGe2S7; a = 6.8653(7) Å, b = 12.368(1) Å, c = 7.1094(6) Å, α = 76.353(2) ˚, β = 81.526(3) ˚, γ = 75.562(3)˚, V = 565.59(8) Å3 for CsCuTiGe2S7. The structures of ACuTiGe2S7 (A = Rb, Cs) consist of the two-dimensional [CuTiGe2S7–] layers separated by alkali metal cations, A+. Each layer contains Ti centered S octahedra, Cu and Ge centered S tetrahedra. The classical charge balance of the compound can be represented by [A+][Cu+][Ti4+][Ge4+]2[S2-]7. The compounds were investigated with solid-state UV/Vis diffuse reflectance spectroscopy which shows an absorption edges and band gaps, Eg are estimated to be ~1.3eV. II. AXNb1-YTaYPS6 (A = K, Rb) Ternary thiophosphate, TaPS6 serves as host structure in the new quintenary thiophosphates, AXNb1-YTaYPS6 (A = K, Rb). The structure of the title compounds contain 3-dimensional open framework with the channels which alkali metal ions (K+ or Rb+) reside. The amount of each metal can vary, [AXNb1-YTaYPS6: A = K, Y = 0.34, 0.50, 0.75; A = Rb, Y = 0.25, 0.30, 0.47, 0.77] and they seem to form solid solutions. The intermetallic M-M distances within the [M2S12] units range from 3.155(1) Å to 3.2707(7) Å, which are considerably shorter compared to that in TaPS6 (dTa-Ta=3.365(1) Å). The electrons released from K or Rb atoms are transferred to the d-orbitals of pair-wise mixed metal (M) by the amount of the alkali metals. Consequently, the interatomic M-M distances are decreased. As a result, the intermetallic bond can be strengthened gradually by the amount of the alkali metals. The classical charge balance of the title compounds can be represented by [A+]X[(Nb/Ta)(5-X)+][P5+][S22-][S2-]4.
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- Graduate School of Ajou University > Department of Energy Systems > 3. Theses(Master)
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