Unravelling ultralow thermal conductivity in perovskite Cs_(2)AgBiBr_(6):dominant wave-like phonon tunnelling and strong anharmonicity  

作　　者：Jiongzhi Zheng Changpeng Lin Chongjia Lin Geoffroy Hautier Ruiqiang Guo Baoling Huang 

机构地区：[1]Department of Mechanical and Aerospace Engineering,The Hong Kong University of Science and Technology,Clear Water Bay,Kowloon,Hong Kong [2]Thayer School of Engineering,Dartmouth College,Hanover,NH 03755,USA [3]Theory and Simulation of Materials(THEOS),École Polytechnique Fédérale de Lausanne,CH-1015 Lausanne,Switzerland [4]National Centre for Computational Design and Discovery of Novel Materials(MARVEL),École Polytechnique Fédérale de Lausanne,CH-1015 Lausanne,Switzerland [5]Thermal Science Research Center,Shandong Institute of Advanced Technology,Jinan 250103 Shandong,China [6]HKUST Foshan Research Institute for Smart Manufacturing,Hong Kong University of Science and Technology,Clear Water Bay,Kowloon,Hong Kong,China [7]HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute,Futian 518055 Shenzhen,China

出　　处：《npj Computational Materials》2024年第1期2933-2945,共13页计算材料学(英文)

基　　金：the financial support from the Science and Technology Planning Project of Guangdong Province,China(Grant No.2017A050506053);the Science and Technology Program of Guangzhou(No.201704030107);the Hong Kong General Research Fund(Grants No.16214217 and No.16206020);supported in part by the Project of Hetao Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone(HZQB-KCZYB2020083);R.G.acknowledges support from the Excellent Young Scientists Fund(Overseas)of Shandong Province(2022HWYQ091);the Taishan Scholars Program of Shandong Province,the Natural Science Foundation of Shandong Province(ZR2022MA011);the Initiative Research Fund of Shandong Institute of Advanced Technology(2020107R03);funding by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division,under Contract No.DE-AC02-05-CH11231:Materials Project program KC23MP.ChangpengL.acknowledges the support from the Sinergia project of the Swiss National Science Foundation(grant number CRSII5_189924).

摘　　要：Understanding the lattice dynamics and heat transport physics in the lead-free halide double perovskites remains an outstanding challenge due to their lattice dynamical instability and strong anharmonicity.In this work,we investigate the microscopic mechanisms of anharmonic lattice dynamics and thermal transport in lead-free halide double perovskite Cs_(2)AgBiBr_(6)from first principles.We combine self-consistent phonon calculations with bubble diagram correction and a unified theory of lattice thermal transport that considers both the particle-like phonon propagation and wave-like tunnelling of phonons.An ultra-low thermal conductivity at room temperature(~0.21Wm^(−1)K^(−1))is predicted with weak temperature dependence(~T^(−0.34)),in sharp contrast to the conventional~T^(−1 )dependence.Particularly,the vibrational properties of Cs_(2)AgBiBr_(6)are featured by strong anharmonicity and wave-like tunnelling of phonons.Anharmonic phonon renormalization from both the cubic and quartic anharmonicities are found essential in precisely predicting the phase transition temperature in Cs_(2)AgBiBr_(6)while the negative phonon energy shifts induced by cubic anharmonicity has a significant influence on particle-like phonon propagation.Further,the contribution of the wave-like tunnelling to the total thermal conductivity surpasses that of the particle-like propagation above around 310 K,indicating the breakdown of the phonon gas picture conventionally used in the Peierls-Boltzmann Transport Equation.Importantly,further including four-phonon scatterings is required in achieving the dominance of wave-like tunnelling,as compared to the dominant particle-like propagation channel when considering only three-phonon scatterings.Our work highlights the importance of lattice anharmonicity and wave-like tunnelling of phonons in the thermal transport in lead-free halide double perovskites.

关 键 词：harmonic PHONON PEROVSKITE 

分 类 号：O57[理学—粒子物理与原子核物理]