Preparation, Crystal Structure and High-Temperature Thermoelectric Properties of Double Perovskite-Type Rare-Earth Cobalt Ruthenium Oxides

Abstract

Rare-earth cobalt ruthenium oxides Ln2CoRuO6 (Ln=La, Pr, Nd, Sm, Eu and Gd) having the double perovskite-type structure were prepared at 1673 K in air. Rietveld analysis of the X-ray diffraction patterns revealed that the oxides crystallized in monoclinic cells with space group P21/n (No. 14). Co/Ru disorder up to 10% was observed at each of the octahedral site in GdCoRuO6. Ln2CoRuO6 oxides were p-type semiconductors with Seebeck coefficient of 180-290 μV·K-1 at 400 K and 72-79 μV·K-1 at 1073 K. The power factors at 1073 K were 1.9-4.3×10-6 W·K-2·m-1.