Thermal Transport Measurements of LaCoO 3 and SrTiO 3

Thermal conductivity and thermopower measurements as functions of temperature were carried out on SrTiO 3 single crystals below room temperature and compared to those obtained for LaCoO 3 polycrystalline samples. The maximum value of thermal conductivity for SrTiO 3 (110) and Nb-doped SrTiO 3 single crystals was 1.09 and 0.91 W/mK, respectively, at 300 K. The thermopower measurements were − 5.47 and − 41.17 μ V/K, respectively, at 300 K. This indicates the predominance of negative charge carriers or electrons in the material. Measurements on LaCoO 3 polycrystalline samples yielded maximum values of 0.37 W/mK and 620 μ V/K for thermal conductivity and thermopower, respectively. These positive values suggest that positive charge carriers are predominant or that the compound is slightly hole-doped. We studied the effect of Nb doping on the thermopower and thermal conductivity of SrTiO 3 and contrasted the results obtained with similar measurements on LaCoO 3 .