摘要
无污染、低成本和高性能Cu_(1.8)S基类液态热电材料受到关注.但是,其过高的本征Cu空位和Cu离子迁移特性限制了其性能和电稳定性的进一步提升.本研究采用机械合金化结合放电等离子体烧结制备了一系列Cu_(1.8)S和Mn_(x)Cu_(1.8)S_(0.5)Se_(0.5)(0.01≤x≤0.06)块体热电材料.随着Se和Mn的引入,体系由低熵Cu_(1.8)S(0.4R^(*))转变为中熵MnxCu_(1.8)S_(0.5)Se_(0.5)(1.2R^(*)).构型熵的增加不仅提高了体系的结构对称性,MnxCu_(1.8)S_(0.5)Se_(0.5)室温下呈立方相结构,还增大了Mn的固溶度.高浓度Mn固溶有效填补了过高的本征Cu空位,降低了载流子浓度,优化了能带结构,提升了电输运性能.熵工程一方面增大了Cu离子迁移势垒,抑制Cu离子迁移.750 K下,即使电流密度达到24 A cm^(-2),Mn_(0.03)Cu_(1.8)S_(0.5)Se_(0.5)的电阻也几乎没有变化,显示出优异的电稳定性;同时可降低声速,软化晶格,降低晶格热导率.Mn_(0.06)Cu_(1.8)S_(0.5)Se_(0.5)的块体样品在773 K时获得最大ZT值0.79,相较于初始样品提高了两倍.结果表明熵工程结合Cu空位工程是提升Cu_(1.8)S基热电材料性能的有效策略.
Cu_(1.8)S-based thermoelectric(TE)materials have garnered considerable interest due to their pollution-free,lowcost,and superior performance characteristics.However,high Cu vacancy and Cu migration inhibit their performance and electrical stability improvement.Through mechanical alloying and spark plasma sintering,a series of Cu_(1.8)S and Mn_(x)Cu_(1.8)-S_(0.5)Se_(0.5)(0.01≤x≤0.06)bulk samples were prepared in this study.With Se alloying and Mn doping,the configuration entropy of Mn_(x)Cu_(1.8)S_(0.5)Se_(0.5) increases from low-entropy 0.4R^(*)for pristine Cu_(1.8)S to medium-entropy 1.2R^(*)for Mn_(x)Cu_(1.8)S_(0.5)-Se_(0.5).Mn_(x)Cu_(1.8)S_(0.5)Se_(0.5) subsequently crystallized in a cubic phase with enhanced symmetry and Mn solid solubility.High solubility enables the filling of excessive Cu vacancies,the reduction of carrier concentration,the adjustment of band structure,the enhancement of the Cu migration energy barrier,and the inhibition of Cu migration.Even at current densities exceeding 25 A cm^(−2) at 750 K,the resistance of Mn_(0.03)Cu_(1.8)S_(0.5)Se_(0.5) remained hardly changed,indicating a vastly improved electrical stability.In addition,the ultralow thermal conductivity of the lattice is achieved by decreasing the sound velocity and softening the lattice.At 773 K,the bulk ZT of Mn_(0.06)Cu_(1.8)S_(0.5)Se_(0.5) reaches a maximum of 0.79,which is twice that of pure Cu_(1.8)S.The results indicate that combining entropy engineering and Cu vacancy engineering is an effective strategy for developing high-performance Cu_(1.8)S TE materials.
作者
周炜
李和章
单帜航
张瑞
卢士阔
裴俊
葛振华
周敏
王愿兵
张波萍
Wei Zhou;Hezhang Li;Zhihang Shan;Rui Zhang;Shikuo Lu;Jun Pei;Zhenhua Ge;Min Zhou;Yuanbing Wang;Boping Zhang(Beijing Municipal Key Laboratory of New Energy Materials and Technologies,School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China;National Institute for Materials Science(NIMS),Tsukuba 3050047,Japan;Faculty of Materials Science and Engineering,Kunming University of Science and technology,Kunming 650093,China;Key Laboratory of Cryogenics,Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China;Wuhan Joule Yacht Science&Technology Co.,Ltd.,Wuhan 430070,China)
基金
supported by the National Key R&D Program of China(2018YFB0703603)
the State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(KF202111)。
