2004/09/21 by Dexuan Huo, D. Huo, T. Sakata +14 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Magnetic and transport properties of perovskites and related materials #Thermal Expansion and Ionic Conductivity #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.71.075113
published as Phys. Rev. B 71 (2005) 075113. · 6 pages, 6 figures, submitted to Phys. Rev. B
arxiv created 2004/09/21 · openalex publication_date 2005/02/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We report the electrical resistivity \ensuremathρ, Hall coefficient RH, thermoelectric power S, specific heat C, and thermal conductivity \ensuremathκ on single crystals of the type-VIII clathrate Ba8Ga16Sn30 grown from Sn-flux. Negative S and RH over a wide temperature range indicate that electrons dominate electrical transport properties. Both \ensuremathρ(T) and S(T) show typical behavior of a heavily doped semiconductor. The absolute value of S increases monotonically to 243\phantom\rule0.3em0ex\ensuremathμV∕K with increasing temperature up to 550\phantom\rule0.3em0exK. The large S may originate from the low carrier concentration n=3.7\ifmmode×\else\texttimes\fi1019\phantom\rule0.3em0excm^\ensuremath-3. Hall mobility \ensuremathμH shows a maximum of 62\phantom\rule0.3em0excm2∕V\phantom\rule0.2em0exs around 70\phantom\rule0.3em0exK. The analysis of temperature dependence of \ensuremathμH suggests a crossover of a dominant scattering mechanism from ionized impurity to acoustic phonon scattering with increasing temperature. The existence of local vibration modes of Ba atoms in cages composed of Ga and Sn atoms is evidenced by analysis of experimental data of structural refinement and specific heat, which give an Einstein temperature of 50\phantom\rule0.3em0exK and a Debye temperature of 200\phantom\rule0.3em0exK. This local vibration of Ba atoms should be responsible for the low thermal conductivity (1.1\phantom\rule0.3em0exW∕m\phantom\rule0.2em0exK at 150\phantom\rule0.3em0exK). The potential of type-VIII clathrate compounds for thermoelectric application is discussed.