二元氧化物Yb_(3)TaO_(7)的非晶状热传导机理  

Mechanism of amorphous-like thermal conductivity in binary oxide Yb_(3)TaO_(7)

作　　者：王学智 汤雨婷 车军伟 令狐佳珺 侯兆阳 Wang Xue-Zhi;Tang Yu-Ting;Che Jun-Wei;Linghu Jia-Jun;Hou Zhao-Yang(Department of Applied Physics,School of Science,Chang’an University,Xi’an 710064,China;State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,College of Mechanical and Vehicle Engineering,Hunan University,Changsha 410082,China;MOE Key Lab for Non-equilibrium Synthesis and Modulation Condensed Matter,School of Physics,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]长安大学理学院应用物理系,西安710064 [2]湖南大学机械与运载工程学院,汽车车身先进设计制造国家重点实验室,长沙410082 [3]西安交通大学物理学院,教育部物质非平衡合成与调控重点实验室,西安710049

出　　处：《物理学报》2023年第5期267-277,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12204063);中央高校基本科研业务费专项资金(批准号:300102122112);陕西省自然科学基础研究计划(批准号:2020JQ-339)资助的课题。

摘　　要：具有非晶状热导率的固体材料在热能转换和热管理应用中备受青睐.因此,揭示晶体材料的非晶状热传导机理对于开发和设计低热导率材料至关重要.本文运用原子模拟方法揭示了萤石结构二元简单晶体Yb_(3)TaO_(7)的非晶状低热导率的物理机理.研究发现,萤石Yb_(3)TaO_(7)的低热导率主要是由O-Yb和O-Ta之间的原子间结合力相差较大引起的.这种相差较大的原子键可以极大地软化声子模式,从而抑制声子输运.振动模式分解显示,萤石Yb_(3)TaO_(7)中的大多数声子模式位于Ioffe-Regel极限以下,表现出强烈的扩散特征.萤石Yb_(3)TaO_(7)中绝大部分(>90%)的热流是通过扩散模式而不是传播模式传输.因此,萤石Yb_(3)TaO_(7)中的热传导表现出独特的类非晶特性.同时发现,萤石Yb_(3)TaO_(7)中的光学声子模式在热传导中发挥着重要的作用.本文对于原子间结合力与低热导率之间关系的认识,以及开发和设计低热导率材料提供了新思路.The materials with low thermal conductivity(κ)are both fundamentally interesting and technologically important in applications relevant to thermal energy conversion and thermal management,such as thermoelectric conversion devices,thermal barrier coatings,and thermal storage.Therefore,understanding the physical mechanisms of glass-like heat conduction in crystalline materials is essential for the development and design of low-κmaterials.In this work,the microscopic phonon mechanism of glass-like lowκin binary simple crystal Yb_(3)TaO_(7)with fluorite structure is investigated by using the equilibrium molecular dynamics,phonon spectral energy density,and lattice dynamics.Meanwhile,the weberite-structured Yb_(3)TaO_(7)is also mentioned for comparison.The calculatedκindicates that fluorite Yb_(3)TaO_(7)has a glass-like lowκwhile weberite Yb_(3)TaO_(7)has a crystalκ.Such a lowκin fluorite Yb_(3)TaO_(7)is mainly due to the large difference in interatomic force between O-Yb and O-Ta.This different atomic bonding can significantly soften the phonon mode and thus limit phonon transport.To further describe the microscopic phonon thermal conduction,the single-channel model based on the phonon gas model is first used to calculate the totalκ,However,the single-channel model significantly underestimates theκ,suggesting the presence of non-normal phonons in Yb_(3)TaO_(7).Based on this,vibrational mode decomposition is conducted throughout the entire phonon spectrum of fluorite-and weberitetype Yb_(3)TaO_(7).It is found that most modes in fluorite Yb_(3)TaO_(7)fall in the Ioffe-Regel regime and exhibit a strongly diffusive nature.Such diffusive modes cannot be described by the phonon gas model.Based on the decomposed phonon modes,the dual-channel model involving diffusive mode and propagating mode is used to describe the phonon thermal conduction,by which the obtained results accord well with the experimental values.The vast majority(>90%)of heat in fluorite Yb_(3)TaO_(7)is found to be transported by diffusive modes rat

关 键 词：非晶热导率 声子输运 扩散声子 热障涂层 

分 类 号：TB34[一般工业技术—材料科学与工程] O48[理学—固体物理]