Synthesis and Characterization of Ca_2.7−xAg_0.3Eu_xCo₄O₉ Semiconducting Materials for Thermoelectric Generators

In the area of thermoelectric implementation, the development of thermoelectric materials takes a crucial role, especially in areas with substantial thermal differentials, aiming to convert these differentials into electrical signals. This study systematically describes the production and characterization of Ca_2.7−xAg_0.3Eu_xCo₄O₉ materials for use in thermoelectric applications, necessitating robust systems capable of harnessing temperature differences for power generation. These ceramics are synthesized using the sol–gel technique using precursor materials. After the gelation process, the obtained xerogel was desiccated and calcined to acquire the final Ca_2.7−xAg_0.3Eu_xCo₄O₉ bulk materials. Comprehensive characterization, encompassing thermal, structural, microstructural, and thermoelectric characteristics, is performed with methods such as XRD, DTA-TG, XPS, FTIR, SEM, and thermoelectric measuring instruments. XRD and XPS results confirmed the crystalline nature of the synthesized Ca_2.7−xAg_0.3Eu_xCo₄O₉ ceramic powders and verified the inscription of Eu and Ag dopants into Ca₃Co₄O₉ ceramic powder materials, illustrating the successful fabrication of p-type thermoelectric materials. Thermoelectric results showed that electrical resistivity and the Seebeck coefficient were measured as 9.39 mΩcm, and 242.15 µV/K respectively, which yields a maximum power factor of 0.62 smW/mK² at 800°C. According to these results, the study determines that the manufactured semiconducting ceramic materials illustrate high performance for high-performance thermoelectric generator fabricating.