Advancement of High‐Efficiency n‐Type ZnAlGaO Materials for Aerospace Thermoelectric Energy Harvesting

ABSTRACT The development of high‐performance n‐type thermoelectric materials for application in aerospace energy harvesting systems is the main objective of this work. We present an innovative synthesis approach for ZnAlGaO‐based semiconductors, utilizing a refined sol–gel technique with water‐based precursor solutions and the inclusion of glacial acetic acid to facilitate gelation. The process carefully controls solution pH and turbidity through precise instrumentation, ensuring the formation of uniform gels. Following gelation, the xerogel undergoes an optimized drying procedure at 200°C to remove residual compounds. High‐purity ZnAlGaO materials are then created by calcining the resultant powders at 600°C. A novel thermal process at 1350°C for 36 h was implemented to improve the bulk thermoelectric characteristics of the material. Detailed characterization techniques, including DTA‐TG, SEM, FTIR, XRD, XPS, and thermoelectric measurements, confirm the superior performance of the fabricated materials. The n‐type ceramics exhibit a remarkable thermoelectric figure of merit of 0.172 at 800°C, making them promising candidates for thermoelectric generator applications in aerospace technologies.