Enhanced thermoelectric properties of Ca3Co4O9 by adding nano MoSi2

Adding nanoparticles is a method to regulate the performance of thermoelectric materials. Ca 3 Co 4 O 9 /x MoSi 2 (x = 0, 0.05, 0.10, 0.13, and 0.16) was synthesized by a wet chemical method combined with atmospheric pressure sintering. The XRD and SEM results reveal that there are no other reaction in the samples. The grain size of all samples decrease with increasing MoSi 2 content, and all presented a similar flake morphology. The influence of MoSi 2 on the thermoelectric performance of Ca 3 Co 4 O 9 is systematically analysed. The appropriate addition of nano-MoSi 2 particles can increase the carrier concentration and enhance conductivity of Ca 3 Co 4 O 9 . The electrical conductivity of Ca 3 Co 4 O 9 /0.05 MoSi 2 is 83.16 Scm −1 , which is 49.2% higher than that of Ca 3 Co 4 O 9 at 1080 K. The Seebeck coefficient of the Ca 3 Co 4 O 9 /0.16 MoSi 2 sample reaches 197.56 μVK −1 at 980 K, which is significantly better than that of previously reported samples prepared by the same method. Moreover, combined with the experimental results and the analysis of the effective medium theory model, the addition of MoSi 2 can effectively debase the thermal conductivity of Ca 3 Co 4 O 9 . The thermal conductivity of Ca 3 Co 4 O 9 /0.16 MoSi 2 (∼1.26 Wm −1 K −1 , 1080 K) samples decrease greatly, which is attributed to the influence of interfacial thermal resistance and pores in the Ca 3 Co 4 O 9 /MoSi 2 . The ZT value of the Ca 3 Co 4 O 9 /0.05 MoSi 2 sample increases by 44.4% compare with that of Ca 3 Co 4 O 9 and reaches 0.26 at 1080 K. These results demonstrate that adding an appropriate amount of MoSi 2 particles is one of the methods to enhance the thermoelectric performance of Ca 3 Co 4 O 9 ceramic samples.