Enhancement of Ca3Co4O9+δ thermoelectric properties by dispersing SiC nanoparticles

Misfit-layered oxides Ca 3 Co 4 O 9+δ  +  z wt% SiC ( z  = 0.00, 0.025, 0.05, 0.1, 0.2) samples were synthesized using solid-state sintering method and the effects of SiC nanoparticles diapersion on the thermoelectric properties were investigated. Thermoelectric properties of Ca 3 Co 4 O 9+δ  +  z wt% SiC ( z  = 0.00, 0.025, 0.05, 0.1, 0.2) were investigated up to 923 K. Compared with pure sample, the electrical resistivity of SiC-added samples reduces, for Ca 3 Co 4 O 9+δ  +  z wt% SiC ( z  = 0.00, 0.025, 0.05, 0.1, 0.2) ceramic samples with x ≤ 0.05, the electrical resistivity decreases with increasing SiC nanoparticles adding amounts. And, the electrical resistivity exists transition from semiconductor to metal conduction mechanism. While, the thermal conductivity also decreases due to the addition of SiC nanoparticles . As a result, the Ca 3 Co 4 O 9+δ + 0.2 wt% SiC sample had the lowest thermal conductivity of 1.47 W/Km at 923 K, which was 18.4% lower than that of the Ca 3 Co 4 O 9+δ sample. The ZT value of Ca 3 Co 4 O 9+δ + 0.05 wt% SiC can reach 0.218, which is 40.9% higher than the pure Ca 3 Co 4 O 9+δ sample.