Effect of SiC and nano-Ag on the structure and properties of Ca₃Co₄O₉ ceramics

In this study, Ca₃Co₄O₉ ceramic samples incorporating SiC of different crystal structures were initially prepared using the solid-state method under ambient atmosphere. The results indicated that the electrical conductivity and PF of samples containing α-SiC are better than those of the composite β-SiC samples. Therefore, α-SiC was selected as one of the composite dopants. To further enhance the electrical conductivity, Ag was introduced as an additional dopant, leading to the fabrication of Ca₃Co₄O₉-10 wt%Ag-xwt.%α-SiC ceramics. The findings demonstrated that when the α-SiC content was 0.08 wt%, the prepared Ca₃Co₄O₉-10 wt%Ag-0.08 wt%α-SiC composite exhibited optimal thermoelectric properties at 600 °C. The PF reached 269 μW/(K²·m), representing a 143% improvement over Ca₃Co₄O₉. The minimum thermal conductivity (κ) was 0.736 W/(m·K), yielding a maximum ZT value of 0.319.