Investigating Fe and Cr doping effects on thermoelectric efficiency in Mg₃Sb₂ through first-principles calculations for sustainable energy solutions

The thermoelectric performance of Mg₃Sb₂ was systematically enhanced through doping with chromium (Cr) and iron (Fe), offering new insights into advanced materials for energy conversion applications. Using first-principles calculations within the CASTEP framework and Boltzmann transport theory in BoltzTraP, the study evaluated the electronic structure and thermoelectric properties of doped Mg₃Sb₂. Cr doping led to a significant increase in the Seebeck coefficient, reaching 739 µV/K, and an electronic ZT (eZT) value of 0.82—demonstrating a 40% improvement in thermoelectric efficiency compared to undoped Mg₃Sb₂. Fe doping further reduced the bandgap to 0.086 eV, optimizing carrier transport and achieving a Seebeck coefficient of 730 µV/K and a maximum electronic ZT (eZT) of 0.966—a 55% enhancement over the pristine material and 18% higher than Cr-doped variants. These findings represent a significant advancement over previously reported thermoelectric materials, showcasing the potential of Cr and Fe doping to strategically tailor electronic structures and minimize electronic thermal conductivity. With superior eZT values, Fe-doped Mg₃Sb₂ emerges as a promising candidate for next-generation thermoelectric applications, including waste heat recovery, renewable energy systems, and sustainable power generation technologies. This study underscores the critical role of transition metal doping in driving the design of high-performance thermoelectric materials, offering transformative prospects for energy efficiency and sustainability.