Sol–Gel Synthesis of Ca_2.5Ag_0.3Sm_0.2Co₄O₉ Semiconducting Materials for Thermoelectric Applications in Aerospace Systems

Thermoelectric materials have gained significant attention for energy harvesting and waste heat recovery, particularly in aerospace applications. The layered Ca₃Co₄O₉ structure, a member of the misfit-layered cobaltite family, has been extensively studied for its high thermoelectric performance. Herein, Ca_2.5Ag_0.3Sm_0.2Co₄O₉ ceramic materials are synthesized via the sol–gel method to enhance their thermoelectric properties. Various characterization techniques, including differential thermal analysis thermogravimetry, X-ray diffraction, X-ray Photoelectron Spectroscopy, scanning electron microscopy, and thermoelectric characterization, are employed to analyze the thermal, structural, and morphological properties of the synthesized materials. The thermoelectric properties are evaluated through the Seebeck coefficient, electrical resistivity, and power factor measurements. The incorporation of Ag and Sm as dopants improves the electrical conductivity and thermopower, making these materials suitable for aerospace thermoelectric systems.