Energy dissipation in the form of heat from sources such as automobiles, aircraft turbines, power plants, and factories is largely unrecovered, accounting for approximately 70% of the primary energy produced. To address this challenge, thermoelectric energy converters can partially recover this wasted heat and improve system efficiency. Thermoelectric generators (TEGs), made from semiconducting materials, are ideal for such applications. Conventional thermoelectric generators utilize intermetallic compounds, such as lead and bismuth tellurides or silicon-germanium alloys. However, these materials face limitations such as decomposition at relatively low temperatures, low precursor availability, high toxicity, and high cost. As a result, thermoelectric oxides have emerged as a more favourable alternative, as they avoid many of the drawbacks associated with intermetallic compounds. This study synthesized barium-doped calcium cobalt oxide (Ca3-xBaxCo4O9, x = 0.0, 0.02, 0.04, 0.08%) thermoelectric samples using the Sol-gel method. The thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and thermal conductivity, were systematically investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyzed phase purity and surface morphology. XRD confirmed that all samples exhibited a single-phase structure. The doping of barium resulted in enhanced thermoelectric properties, as evidenced by significant improvements in the dimensionless Figure of merit, which reached 1.35 × 10⁻¹² at room temperature, compared to the undoped sample with a zT of 1.16 × 10⁻¹². These findings demonstrate the potential of the sol-gel method to synthesize barium-doped thermoelectric materials with improved thermoelectric performance, offering promising prospects for more efficient energy conversion in various applications.

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