材料科学技术(英文版)2024，Vol.187Issue(20) ：248-257.DOI:10.1016/j.jmst.2023.11.039

Thermoelectric properties of heavily Co-doped β-FeSi2

Jun Cheng Lu Gan Jiawei Zhang Jinyang Xi Lili Xi Jiong Yang Tingting Deng Pengfei Qiu Xun Shi Lidong Chen
材料科学技术(英文版)2024，Vol.187Issue(20) ：248-257.DOI:10.1016/j.jmst.2023.11.039
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Thermoelectric properties of heavily Co-doped β-FeSi2

Jun Cheng 1Lu Gan 2Jiawei Zhang 1Jinyang Xi 2Lili Xi 2Jiong Yang 2Tingting Deng 3Pengfei Qiu 4Xun Shi 1Lidong Chen1
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作者信息

  • 1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China
  • 2. Materials Genome Institute,Shanghai University,Shanghai 200444,China
  • 3. School of Chemistry and Materials Science,Hangzhou Institute for Advanced Study,University of Chinese Academy of Sciences,Hangzhou 310024,China
  • 4. State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;School of Chemistry and Materials Science,Hangzhou Institute for Advanced Study,University of Chinese Academy of Sciences,Hangzhou 310024,China
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Abstract

Element doping is a widely employed strategy to enhance the thermoelectric(TE)properties of various materials.β-FeSi2 is a promising low-cost high-temperature TE material with exceptional thermal stabil-ity;however,the doping limit of β-FeSi2 is usually very low,which limits the tunability of electrical and thermal properties.Recently,a high doping content of 0.16 in β-FeSi2 has been achieved by the introduc-tion of iridium(Ir),leading to the highest reported figure of merit(zT)of 0.6 in β-FeSi2.Motivated by the successful heavy doping with Ir,this work aims to explore element heavy doping in β-FeSi2 with cobalt(Co),a cheaper,more readily available dopant with a smaller atomic radius and closer electronegativity to iron(Fe).In this study,we successfully obtained a record-high doping content of 0.24 in Co-dopedβ-FeSi2 through a prolonged annealing process.Despite the absence of a substantial enhancement in the zT of Co-doped β-FeSi2 at high doping levels,with a maximum zT of 0.3 at 900 K in Fe0.92Co0.08Si2,we observed a transition in the carrier transport mechanism as a function of Co doping content,attributed to changes in the band structure.At a low Co doping content(x ≤ 0.12),Fe1-xCoxSi2 demonstrates dominant carrier transport via impurity levels within the band gap,exhibiting hopping conduction.As the Co dop-ing content increases(x＞0.16),the impurity levels overlap and form an impurity band,and the carrier transport turns into the impurity band conduction.The observed band conduction behavior of Fe1-xCoxSi2(x＞0.16)mirrors that of Ir-doped β-FeSi2,but Fe1-xCoxSi2 shows much lower mobility,which can be at-tributed to the localized feature of the impurity band introduced by the Co doping.Overall,this study provides insights into the heavy Co doping and its influence on the TE properties and carrier conduction mechanisms in β-FeSi2,helpful for the further development of this TE system.

Key words

β-FeSi2/Heavy doping/Hopping/Band conduction

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基金项目

National Natural Science Foundation of China(91963208)

National Natural Science Foundation of China(52232010)

National Natural Science Foundation of China(52122213)

Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(JCYJ-SHFY-2022-002)

Shanghai Government(20JC1415100)

synchrotron beamline RIKEN BL44B2(2023A1294)

出版年

2024
材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCDCSCD
影响因子：0.657
ISSN：1005-0302
参考文献量54
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