Enhancing thermoelectric performance in GeTe through Ge enrichment regulation and AgCuTe alloying

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-04, Vol.485, p.149695, Article 149695
• Main Authors: Lyu, Jingyi, Li, Jingfeng, Yang, Wenwei, Chen, Zhixing, Ren, Zijie, Zhao, Zhanpeng, Liu, Shenghua, Shuai, Jing
• Format: Article
• Language: English
• Subjects: AgCuTe-alloying; Ge vacancies; GeTe; Lattice thermal conductivity
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.149695

The quenching process effectively reduces Ge enrichment, while the introduction of Bi to GeTe efficiently regulates the carrier concentration to the optimal level. Moreover, the incorporation of AgCuTe alloying, with its capacity to lower the Ge enrichment and introduce the secondary phase Cu2Te, significantly decreases the lattice thermal conductivity to the amorphous level. Ultimately, the (Ge0.94Bi0.06Te)0.98(AgCuTe)0.02 sample demonstrates a remarkable peak ZT value of approximately 2.27 at 773 K. [Display omitted] •The quenching process reduces Ge’s enrichment, leading to reduced thermal conductivity.•AgCuTe alloying introduces Cu2Te and regulates the ratio of Ge/Te.•The (Ge0.94Bi0.06Te)0.98(AgCuTe)0.02 sample exhibits a peak ZT of ∼2.27 at 773 K. Germanium telluride (GeTe) exhibits substantial potential as a thermoelectric material well-suited for mid-temperature applications. The presence of a significant amount of off-stoichiometric Ge leads to the formation of Ge precipitates and vacancies, which exert a pronounced influence on the electrical and thermal transport properties of GeTe. In this study, a heat treatment process is initially applied to alleviate Ge enrichment within pristine GeTe, resulting in the achievement of a uniform distribution of Ge precipitates throughout the matrix. Subsequently, we coarsely optimize the carrier concentration through Bi counter-doping, thereby attaining the desired range for optimal performance. Notably, we finely adjust the Ge/Te ratio through AgCuTe alloying, effectively modulating Ge precipitation, reducing lattice thermal conductivity, and enhancing the thermoelectric performance of GeTe. Consequently, the synthesized sample (Ge0.94Bi0.06Te)0.98(AgCuTe)0.02 exhibits a peak ZT value of approximately 2.27 at 773 K, with an average ZT value of approximately 1.38 within the temperature range of 323 to 773 K, making this material as a prominent candidate for medium-temperature thermoelectric applications.