Thermoelectrical and Structural Properties of Sintered LaCoO$_{3}$ Ceramics

Electrical and thermal transport properties of LaCoO$_{3}$ in bulk are reported in the temperature range from 10 to 390 K. The crystalline structure of the samples was determined by x-ray diffractometry (XRD). XRD measurements indicated that the formation of LaCoO$_{3}$ was completed, and it was verified that a pure phase with rhombohedral crystalline structure was obtained. The results of the thermoelectric measurements show that the Seebeck coefficient ($S)$ initially grow with the increasing of temperature up to a maximum value around of 650 $\mu $V/K at 230 K. After this temperature $S$ decrease slowly up to a value of 520 $\mu $V/K, at room temperature. The polycrystalline LaCoO$_{3}$ samples show thermal conductivity around 0.4 W$/$mK at room temperature, that is a lower value than the reported for single crystal samples of this material. Electrical resistivity measurements show typical semiconducting behavior, with a large value of resistivity, close to 2.6 $\Omega $cm. Finally the thermoelectric figure of merit have a maximum value of 0.09, at room temperature, that is comparable to previous reported values for this material.