Perovskite-type rare earth cobalt oxide Pr1−xDyxCoO3 (x = 0, 0.25, 0.5, 0.75 and 1) ceramics were fabricated by reaction sintering of the corresponding metal oxide powders, and their thermoelectric properties were evaluated up to 873 K. The electrical properties of Pr1−xDyxCoO3 varied according to a variation in the x value, whereas the thermal conductivity of the solid solutions (x = 0.25 − 0.75) tends to be lower than that of both end components (x = 0 and 1). As the results, Pr0.75Dy0.25CoO3 (x = 0.25) showed the highest figure of merit, Z = 5.72 × 10−5 K−1 at 773 K in the present Pr1−xDyxCoO3 system. This is considered due mainly to the effect of decreasing thermal conductivity caused by phonon scattering of partially substituted A-site ions. These results suggest that the fabrication of solid solutions is effective in improving the thermoelectric properties of the RCoO3 system.

Keywords: Thermoelectric properties, Perovskite, Rare earth cobalt oxides, Solid solutions, Phonon scattering