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- Title
A Combined Metal-Halide/Metal Flux Synthetic Route towards Type-I Clathrates: Crystal Structures and Thermoelectric Properties of A<sub>8</sub>Al<sub>8</sub>Si<sub>38</sub> (A=K, Rb, and Cs).
- Authors
Baran, Volodymyr; Senyshyn, Anatoliy; Karttunen, Antti J.; Fischer, Andreas; Scherer, Wolfgang; Raudaschl ‐ Sieber, Gabriele; Fässler, Thomas F.
- Abstract
Single-phase samples of the compounds K8Al8Si38 ( 1), Rb8Al8Si38 ( 2), and Cs7.9Al7.9Si38.1 ( 3) were obtained with high crystallinity and in good quantities by using a novel flux method with two different flux materials, such as Al and the respective alkali-metal halide salt (KBr, RbCl, and CsCl). This approach facilitates the removal of the product mixture from the container and also allows convenient extraction of the flux media due to the good solubility of the halide salts in water. The products were analyzed by means of single-crystal X-ray structure determination, powder X-ray and neutron diffraction experiments, 27Al-MAS NMR spectroscopy measurements, quantum chemical calculations, as well as magnetic and transport measurements (thermal conductivity, electrical resistivity, and Seebeck coefficient). Due to the excellent quality of the neutron diffraction data, the difference between the nuclear scattering factors of silicon and aluminum atoms was sufficient to refine their mixed occupancy at specific sites. The role of variable-range hopping for the interpretation of the resistivity and the Seebeck coefficient is discussed.
- Subjects
CLATHRATE compounds; ALKALI metal halides; CRYSTALLINITY; X-ray diffraction; NEUTRON diffraction; NUCLEAR magnetic resonance spectroscopy
- Publication
Chemistry - A European Journal, 2014, Vol 20, Issue 46, p15077
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201403416