Wu Yutian, Su Xianli, Yang Dongwang, Zhang Qingjie, Tang Xinfeng
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4185-4191. doi: 10.1021/acsami.0c19387. Epub 2021 Jan 12.
AgBiS is an environmentally friendly n-type thermoelectric material composed of earth-abundant and nontoxic elements. It has a complex monoclinic structure with distorted NaCl-type fragments, which provide its intrinsically low thermal conductivity. However, poor electrical properties limit its overall performance. Configurational entropy engineering is an effective method to enhance thermoelectric properties. With the increase of configurational entropy, phonon point defect scattering is amplified, yielding lower lattice thermal conductivity, while the structure symmetry can also be improved, which leads to the enhanced electrical transport property. In this study, we combine carrier modulation and entropy engineering, utilizing melting-annealing and spark plasma sintering, to synthesize a series of AgBi(SeS) bulks. Se substitution effectively increases the configurational entropy and thus dramatically decreases the thermal conductivity. Moreover, anion deficiency modulation effectively optimizes the carrier concentration and the electrical transport properties. Due to a power factor of 2.7 μW/(cm·K) and a low thermal conductivity of 0.45 W/(m·K) at 723 K, the AgBi(SeS) sample possesses the highest of 0.42 at 723 K, nearly double the value of AgBiS or pristine AgBiS. Our work demonstrates that apart from carrier optimization, entropy engineering opens a new avenue for enhancing the thermoelectric properties of a given material.
AgBiS是一种环境友好型n型热电材料，由储量丰富且无毒的元素组成。它具有复杂的单斜结构，带有扭曲的NaCl型片段，这使其固有热导率较低。然而，较差的电学性能限制了其整体性能。构型熵工程是提高热电性能的有效方法。随着构型熵的增加，声子点缺陷散射被放大，导致晶格热导率降低，同时结构对称性也得以改善，进而使电输运性能增强。在本研究中，我们结合载流子调制和熵工程，利用熔融退火和放电等离子体烧结，合成了一系列AgBi(SeS)块体。Se替代有效地增加了构型熵，从而显著降低了热导率。此外，阴离子缺陷调制有效地优化了载流子浓度和电输运性能。由于在723 K时功率因子为2.7 μW/(cm·K)且热导率低至0.45 W/(m·K)，AgBi(SeS)样品在723 K时具有高达0.42的最高品质因数，几乎是AgBiS或原始AgBiS值的两倍。我们的工作表明，除了载流子优化之外，熵工程为提高给定材料的热电性能开辟了一条新途径。
