High performance Ca_3−xAg_0.3La_xCo₄O₉ materials for aerospace applications of thermoelectric devices

In the domain of aviation applications, the utilization of thermoelectric materials holds significant importance, particularly in regions characterized by notable thermal gradients, aimed at harnessing these gradients for electricity generation. This study advocates for the adoption of thermoelectric modules, specifically within the operational contexts of fixed-wing aircraft and satellites. These settings require resilient thermoelectric systems capable of effectively exploiting temperature differentials to enable electrical power generation, thus emphasizing the necessity of integrating such modules into their operational frameworks. Accordingly, this paper systematically elucidates the production and characterization of Ca_3−xAg_0.3La_xCo₄O₉ for thermoelectric applications in the aerospace sector. Ca_3−xAg_0.3La_xCo₄O₉ ceramics are synthesized via the sol–gel method employing Ca, Ag, La, and Co precursor materials. Distilled water serves as the solvent to dissolve the precursors, yielding homogeneous solutions. These solutions undergo magnetic stirring at 100 °C to achieve final homogeneity, with citric acid monohydrate introduced as a chelating agent to expedite xerogel formation. pH and turbidity measurements are conducted on the prepared solutions using a pH meter and turbidimeter, respectively. Following the gelation process, the resulting xerogel is dried at 200 °C for 2 h to eliminate moisture and undesirable gases. Subsequently, the dried powders are calcined at 800 °C for 2 h, yielding the final Ca_3−xAg_0.3La_xCo₄O₉ materials. The thermal, structural, microstructural, and thermoelectric properties of the materials are comprehensively characterized utilizing DTA-TG, FTIR, XRD, XPS, SEM, and thermoelectric measurement machines. It is ascertained that the produced semiconducting ceramic materials exhibit efficient suitability for thermoelectric generator production.