Thermal Transport Measurements of LaCoO3 and SrTiO3

Thermal conductivity and thermopower measurements as functions of temperature were carried out on SrTiO3 single crystals below room temperature and compared to those obtained for LaCoO3 polycrystalline samples. The maximum value of thermal conductivity for SrTiO3 (110) and Nb-doped SrTiO3 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 LaCoO3 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 SrTiO3 and contrasted the results obtained with similar measurements on LaCoO3.