Thermoelectric Performance of Magnetically c -Axis Aligned Ca-based Cobaltites

Authors report the preparation and thermoelectric properties of highly grain-oriented and densified [Ca2CoO3-d]0.62CoO2 and [Ca2(Co0.65Cu0.35)2O4]0.624CoO2 bulks. The grain-alignment and densification were performed by magnetic alignment and spark-plasma-sintering (SPS) methods, resp. Both obtained samples with strong c-axis orientation (F > 0.94) and high relative density ( > 98%) which showed highly conductive behaviors up to 1000 K, and their resistivities were almost half of those for samples processed only by SPS. Consequently, the power factors were enhanced up to 5.5x 10-4 and 4.5x 10-4 Wm-1 K-2 for [Ca2CoO3-d]0.62CoO2 and [Ca2(Co0.65Cu0.35)2O4]0.624CoO2 at 1000 K, resp. 19 refs.