摘要
本征低热导率材料的研究具有重要的科学意义,已引起广泛关注.本工作报道了一类具有简单一维晶体结构的超低热导率材料:铋硒卤族化合物(BiSeX,X=Br,I).研究发现,BiSeI的热导率在573K仅为~0.27Wm^-1K^-1,达到了最低本征热导率的理论极限值.本研究采用第一性原理计算结合粉末中子衍射和变温球差扫描透射电子显微镜表征,深入探究了其超低热导率的机制.研究表明,BiSeX的一维结构赋予了材料低热导特性:弱的成键特性、低的声子速度、声学支和光学支的强非简谐性以及Bi和卤族元素较大的偏移效应,从而有效阻碍了声子输运,使得BiSeX具有超低的热导率.本研究提出了在具有一维结构的材料中寻找低传导特性的新思路,该研究思路在热电材料和热障涂层材料等低热传导需求领域中具有广阔的应用前景.
Materials with intrinsically low thermal conductivity are of fundamental interests.Here we report a new sort of simple one-dimensional(1 D)crystal structured bismuth selenohalides(Bi Se X,X=Br,I)with extremely low thermal conductivity of^0.27 W m^-1K^-1 at 573 K.The mechanism of the extremely low thermal conductivity in 1 D Bi Se X is elucidated systematically using the first-principles calculations,neutron powder-diffraction measurements and temperature tunable aberration-corrected scanning transmission electron microscopy(STEM).Results reveal that the1 D structure of Bi Se X possesses unique soft bonding character,low phonon velocity,strong anharmonicity of both acoustic and optical phonon modes,and large off-center displacement of Bi and halogen atoms.Cooperatively,all these features contribute to the minimal phonon transport.These findings provide a novel selection rule to search low thermal conductivity materials with potential applications in thermoelectrics and thermal barrier coatings.
作者
王东洋
黄志伟
张杨
郝丽杰
王广涛
邓司浩
王洪亮
陈洁
何伦华
肖宝
徐亚东
Stephen J.Pennycook
武海军
赵立东
Dongyang Wang;Zhiwei Huang;Yang Zhang;Lijie Hao;Guangtao Wang;Sihao Deng;Hongliang Wang;Jie Chen;Lunhua He;Bao Xiao;Yadong Xu;Stephen J.Pennycook;Haijun Wu;Li-Dong Zhao(School of Materials Science and Engineering,Beihang University,Beijing 100191,China;State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China;Instrumental Analysis Center of Xi’an Jiaotong University,Xi’an Jiaotong University,Xi’an 710049,China;Department of Materials Science and Engineering,National University of Singapore,Singapore 117575,Singapore;Department of Nuclear Physics,Neutron Scattering Laboratory,China Institute of Atomic Energy,Beijing 102413,China;School of Physics,Henan Normal University,Xinxiang 453007,China;Spallation Neutron Source Science Center,Dongguan 523803,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China)
基金
supported by the National Key Research and Development Program of China(2018YFA0702100 and 2018YFB0703600)
the National Natural Science Foundation of China(51772012 and 51632005)
Shenzhen Peacock Plan team(KQTD2016022619565991)
Beijing Natural Science Foundation(JQ18004)
China Postdoctoral Science Foundation Grant(2019M650429)
111 Project(B17002)
the National Science Foundation for Distinguished Young Scholars(51925101)
the financial support from Singapore Ministry of Education Tier 1grant(R-284-000-212-114)for Lee Kuan Yew Postdoctoral Fellowship。