Thermal Conductivity and Dimensionless Figure of Merit of Thermoelectric Rhodium Oxides Measured by a Modified Harman Method

摘要

We have developed a modified Harman method to extract the thermoelectric signal using a squared AC current in the presence of Joule heating, and have measured the thermal conductivity and dimensionless figure of merit of single crystals of the layered rhodium oxide Bi_(0.78)Sr_(0.4)RhO_(3+d) and the pseudo-one-dimensional rhodium oxide Ba_(1.2)Rh_(8)O_(16). We find that these rhodium oxides exhibit a small thermal conductivity of 30 mW/cm K at 200 K and rather large ZT of 0.02 below 200 K. We believe that this method will be a powerful tool for thermal conductivity measurements in sub-millimeter-sized crystals.