Thermoelectric properties and stability of the Re0.2Sr0.8CoO3-delta = Gd, Dy) complex cobalt oxides in the temperature range of 300-800 K

Temperature dependences of the electrical resistivity and Seebeck coefficient of the Re_0.2Sr_0.8CoO_3‒δ Re = Gd, Dy) complex cobalt oxides in the temperature range of 300 – 800 K have been investigated. The effects of ordering in the cation and anion sublattices on the thermoelectric properties has been examined and their comparative analysis has been made. It was found that, in the investigated temperature range, the thermoelectric power factor of the ordered compounds significantly exceeds the analogous parameter of the disordered samples. The temperature dependence of the electrical resistivity was shown to obey the activation law. As the temperature increases, the samples undergo a semiconductor-semiconductor electronic transition with a decrease in the activation energy. The thermoelectric properties of all the samples are shown to be stable in the investigated temperature range. The maximum thermoelectric power factor of the ordered Dy_0.2Sr_0.8CoO_2.67 cobaltite at a temperature of 360 K has been obtained; it amounts to 0.23 µW/(cm·K²), which is a good parameter for this class of materials.