Fig. 2
From: Kondo-like phonon scattering in thermoelectric clathrates
Thermal conductivity data of type-I clathrate single crystals. a Exemplary frequency scan in the 3ω setup. Rectangles show the in-phase, circles the out-of-phase contribution of the temperature oscillation ΔT. The expected linear-in-logarithmic-frequency dependence of the in-phase temperature oscillation of the heater/thermometer line, that is observed at intermediate frequencies (between the hatched areas), is measured with an extremely low noise level. The slope of this dependence (full line) is inversely proportional to the thermal conductivity κ of the studied material. b Temperature-dependent thermal conductivity of all studied materials. The data points represent the phonon thermal conductivities κph, calculated by subtracting an electronic contribution κel (lines and identifier symbols, right axis) from the total measured κ. Each data point above 80 K is determined from the slope of an isothermal ΔT vs log f curve (straight line in a). All sample compositions are given in the Supplementary Table 1
