High temperature transport properties of Ag-added (Ca0.975La0.025)3Co4O9 ceramics

Ag-added (Ca0.975La0.025)3Co4O9 ceramics were fabricated using spark plasma sintering from the precursor powder synthesized by a polyacrylamide gel method. The results indicated that Ag precipitated as a second phase in Ca3Co4O9 matrix. The addition of Ag was effective in enhancing the electrical conductivity and had a slight effect on Seebeck coefficient. In addition, the temperature dependence of electrical conductivity showed that the hole hopping conduction mechanism was dominant for the Ag-added (Ca0.975La0.025)3Co4O9 ceramics. The activation energy remained unchanged with the increasing Ag content. The thermoelectric power factor of Ag-added (Ca0.975La0.025)3Co4O9 ceramics reached about 5×10−4 Wm−1 K−2 at 700 °C, suggesting a promising thermoelectric oxide candidate at high temperatures.