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Establishing synthesis–composition–property relationships for enhanced and reproducible thermoelectric properties of MgAgSb
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2022-09-30 , DOI: 10.1039/d2ta05936c
Amandine Duparchy 1, 2 , Léo Millerand 1, 2 , Julia Camut 1 , Silvana Tumminello 1 , Hasbuna Kamila 1 , Radhika Deshpande 1 , Aidan Cowley 2 , Eckhard Mueller 1, 3 , Johannes de Boor 1, 4
Affiliation  

α-MgAgSb is a promising p-type thermoelectric (TE) with excellent performance from room temperature up to 300 °C with a figure of merit of zTmax = 1.3. This makes MgAgSb a potential Te-free bismuth telluride (Bi2Te3) substitute for cooling and waste heat conversion applications. However, the material is also known for its sensitivity on synthesis conditions as indicated by various reports on the same nominal composition which show greatly differing TE properties and performance. This indicates a fundamental lack of synthesis control and synthesis–composition–property relationship knowledge. In this work, we establish a modified synthesis route with improved control over the effective sample stoichiometry which allows for reproducible high-performance properties (zTmax = 1.34 ± 0.19 at 561 K) and for systematically targeting different thermodynamic states of MgAgSb. This phase boundary mapping reveals that the homogeneity range for MgAgSb is very small (<0.1 at%) and that the TE properties are not governed by different thermodynamic states. Instead, we rationalize that the TE performance of MgAgSb is mainly controlled by the amount and type of secondary phases, mainly affecting the carrier mobility. We conclude that Sb-excess related secondary phases are the least detrimental, leading the way to upscaled synthesis of high-performance material.

中文翻译:

为 MgAgSb 的增强和可重复的热电性能建立合成-成分-性能关系

α-MgAgSb 是一种很有前途的 p 型热电 (TE),在室温至 300 °C 范围内具有出色的性能,品质因数为zT max = 1.3。这使得 MgAgSb 成为潜在的无碲化铋(Bi 2 Te 3) 替代冷却和废热转换应用。然而,该材料还以其对合成条件的敏感性而闻名,正如关于相同标称成分的各种报告所表明的那样,这些报告显示出极大不同的 TE 特性和性能。这表明根本缺乏综合控制和综合-成分-属性关系知识。在这项工作中,我们建立了一种改进的合成路线,改进了对有效样品化学计量的控制,从而实现了可重现的高性能特性(zT max= 1.34 ± 0.19 at 561 K)和系统地针对不同热力学状态的 MgAgSb。该相界映射表明 MgAgSb 的均匀性范围非常小(<0.1 at%),并且 TE 特性不受不同热力学状态的控制。相反,我们认为 MgAgSb 的 TE 性能主要受第二相的数量和类型控制,主要影响载流子迁移率。我们得出结论,与 Sb 过量相关的第二相的危害最小,为高性能材料的大规模合成开辟了道路。
更新日期:2022-09-30
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