On the optical properties of thermoelectric alkali metal chalcogenide compounds
Paraskevopoulos, K. M.
Kanatzidis, M. G.
PublisherAffiliation: Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
Affiliation: Department of Chemistry, Michigan State University, East Lansing, MI 48824, United States
Affiliation: Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia, Cyprus
Correspondence Address: Hatzikraniotis, E.
Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
SourceMaterials Research Society Symposium Proceedings
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Solid solutions of K2Bi8-xSbxSe 13 is an interesting series of complex bismuth-chalcogenide compounds, which are attractive for thermoelectric investigations. The highly anisotropic structure in these compounds results in needle-like morphology along the b- crystallographic axis, leaving structural tunnels where K+ ions reside. The complex electronic structure that arises from a large and low symmetry unit cell and the weakly bound K+ ions, lead to high Seebeck coefficient, highly anisotropic electrical properties and very low thermal conductivity. Reflectivity spectra in the FIR region are presented for several members in the Sb-rich (x≥6) side. Optical investigations are carried out on crystalline and pelletized samples. The received spectra are analyzed, examined comparatively and discussed. Results indicate that upon Bi/Sb substitution in the Sb-rich region, phonons develop a mixed-mode behavior in the FIR spectral region. © 2006 Materials Research Society.