Pushing the limit of thermal conductivity of MAX borides and MABs  

作　　者：Shaohan Li Weiwei Sun Yi Luo Jin Yu Litao Sun Bao-Tian Wang Ji-Xuan Liu Guo-Jun Zhang Igor Di Marco 

机构地区：[1]School of Materials Science and Engineering,Southeast University,Nanjing 211189,China [2]Jiangsu Province Key Laboratory of Advanced Metallic Materials,Southeast University,Nanjing 211189,China [3]SEU-FEI Nano-Pico Center,Key Laboratory of MEMS of Ministry of Education,Southeast University,Nanjing 210096,China [4]Institute of High Energy Physics,Chinese Academy of Sciences(CAS),Beijing 100049,China [5]Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China [6]State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,College of Materials Science and Engineering,Institute of Functional Materials,Donghua University,Shanghai 201620,China [7]Asia Pacific Center for Theoretical Physics,Pohang,Gyeonbuk 790-784,Republic of Korea [8]Department of Physics,POSTECH,Pohang,Gyeonbuk 790-784,Republic of Korea [9]Department of Physics and Astronomy,Uppsala University,Box 516,Uppsala SE-75120,Sweden

出　　处：《Journal of Materials Science & Technology》2022年第2期79-88,共10页材料科学技术（英文版）

基　　金：the National Natural Science Foundation of China(No.51902052);partially supported by“the Fundamental Research Funds for the Central Universities”;supported by appointments to the JRG program at the APCTP through the Science and Technology Promotion Fund and Lottery Fund of the Korean Government,the Korean Local Governments,Gyeongsangbuk-do Province and Pohang City;partially funded by the Swedish Research Council through grant agreement no.2018-05973 for providing the facility support on the numerical calculations in this paper。

摘　　要：The emergence of MAX borides as well as MAB phases attracted great attention because of the renewable developments of ternary ceramics and offering great opportunities in potential applications.However,the number of borides remains limited,and further fundamental descriptions and detailed investigations on various properties are still lacking.In this report,we employ an integrated computational scheme that combines density functional theory with the evolutional algorithm to search for the favorable structures of P-and S-glued ternary borides terminated by Nb metal.We discover that the structures of 212-type,as e.g.Nb_(2)PB_(2)and Nb_(2)SB_(2),belong to the P6m2 space group,while those of 211-type,as e.g.Nb_(2)PB and Nb_(2)SB,prefer to crystallize in the P6_(3)/mmc space group,and the corresponding carbides Nb_(2)PC and Nb_(2)SC are also considered for the sake of completeness and comparative analsys.The predicted Nb_(2)PB_(2),Nb_(2)PB,Nb_(2)SB,Nb_(2)PC and Nb_(2)SC are energetically stable,as revealed by the negative formation energies and by the proposed reaction paths with respect to the most competing phases,as well as dynamically stable,as suggested by the non-imaginary phonon spectra.The thermal conductivities of the six materials show unusual behaviors,particularly for the acoustic and optical contributions,and are accompanied by a strong anisotropy.Most importantly,Nb_(2)PB_(2) is found to be an excellent thermal conductor with a total thermal conductivity of~65 W/(m K),while Nb_(2)SC is found to be an ultra-low thermal conductor,with a total thermal conductivity of~5 W/(m K).These values are clearly outside the currently reported range of thermal conductivities,which makes Nb_(2)PB_(2)and Nb_(2)SC extremely interesting for fundamental research as well as prospective applications with the aid of artificial tunings on the almost independent MB block and the A layer.The discovery of these novel materials is expected to contribute substantially to the rapid development of ternary ceramics and to accelerate at

关 键 词：MAX and MAB phases Density functional theory calculation Structure searching Thermal conductivity 

分 类 号：TQ174.1[化学工程—陶瓷工业]