Investigation of thermoelectric properties of ce and mo doped ceramic CaMn3 material

In this study, the effects of Ce and Mo co-doping on the thermoelectric properties of CaMnO₃-based perovskite-type oxides were investigated. The compounds Ca₁₋ₓCeₓMn₁₋ᵧMoᵧO₃ (x = 0.01, y = 0.01, 0.03, 0.05, 0.10) were synthesized via the conventional solid-state reaction method, and the impact of doping on structural, microstructural, and transport properties was systematically examined. Structural characterization was carried out using X-ray diffraction (XRD), and the results confirmed that all samples exhibited a single-phase orthorhombic perovskite structure. Microstructural analyses were performed using scanning electron microscopy (SEM), which revealed that Mo doping led to a more homogeneous grain size distribution. The histograms derived from SEM images further supported the structural evolution with increasing dopant content. Thermoelectric measurements were conducted in a wide temperature range, and key parameters such as Seebeck coefficient (S), electrical resistivity (ρ), and power factor (PF) were obtained. The results showed that Ce and Mo doping significantly enhanced the thermoelectric performance of CaMnO₃ by improving the charge carrier concentration and optimizing the crystal structure. Particularly, Mo doping contributed to a reduction in resistivity and improved the high-temperature performance due to its electron-donating nature. Finally, a thermoelectric module for high-temperature applications was fabricated by combining the Ca₀.₉₉Ce₀.₀₁Mn₀.₉₉Mo₀.₀₁O₃ (n-type) composition, which exhibited optimum thermoelectric properties, with the p-type counterpart Ca₂.₉₃Sr₀.₀₇Co₄O₉. The module, consisting of 17 p-n pairs and a surface area of 50 × 50 mm², generated a maximum power of 0.045 W at 900 ºC, corresponding to a power density of W/m² and an internal temperature difference (ΔT) of 358 ºC.