Fabrication and Characterization of Ca ₃ Co ₄ O _x ‐Based Thermoelectric Composites

In this study, the effect of boron and graphene oxide addition to calcium cobalt oxide (CCO, Ca 3 Co 4 O x ) on electrical and structural properties was investigated. For this purpose, three different polymer solutions were prepared, and thermoelectric (TE) nanocomposite materials in powder form were obtained from these solutions using the sol‐gel method. Scanning electron microscopy was employed to investigate the morphologies of the CCO‐based TE nanocomposite powders. Fourier transform infrared spectroscopy and X‐ray diffraction methods were used for the characterization of the compounds for further analysis. The powders were pressed as pellets and sintered at an optimum temperature of 900°C for 3 h under ambient air. The electrical transport properties, including electrical conductivity, the power factor (PF), and Seebeck coefficient, were measured in the temperature range of 50°C–500°C after the sintering process. The resulting measurements revealed that all samples behaved as p‐type materials with a Seebeck coefficient between 106.3 and 134.5 μV/K in magnitude, which varied depending on the temperature. The electrical conductivity was found to be as high as 143.5 Ω −1 m −1 , and the highest PF was 2.6 μW/mK 2 . Furthermore, the PF of the material was significantly enhanced by doping with graphene oxide, attributed to enhanced carrier mobility and improved intergranular connectivity.