Anharmonic guest atom oscillation has direct connection to the thermal transport
and thermoelectric behavior of type-I Ba8Ga16Sn30 clathrates. This behavior can
be observed through several physical properties, with for example the heat
capacity providing a measure of the overall excitation level structure. Localized
anharmonic excitations also influence the low-temperature resistivity, as we show
in this paper. By combining heat capacity, transport measurements, and our
previous NMR relaxation results, we address the distribution of local oscillators
in this material, as well as the shape of the confining potential and the
excitation energies for Ba(2) ions in the cages. We also compare to the soft-potential
model and other models used for similar systems. The results show good agreement
between the previously deduced
anharmonic rattler potential and experimental data.
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