氮化硼纳米管热输运性能的分子动力学模拟  

Molecular Dynamics Simulation of Thermal Transport Properties for Boron Nitride Nanotubes

作　　者：高宇飞[1] 孟庆元[1] 张璐[2] 刘甲秋[3] 荆宇航[1] 

机构地区：[1]哈尔滨工业大学航天学院,哈尔滨150001 [2]中国医科大学,沈阳110001 [3]哈尔滨玻璃钢研究院,哈尔滨150001

出　　处：《物理化学学报》2012年第5期1077-1084,共8页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(10772062)资助项目~~

摘　　要：采用基于声子散射理论的Boltzmann-Peierls声子传输方程(BTE)和非平衡态分子动力学模拟(NEMD)方法研究了氮化硼纳米管(BNNT)的热输运性能.分析了BNNT的热力耦合效应,通过BTE与NEMD两种方法相结合,分析了温度和长度对BNNT热输运性能的影响,并应用量子修正扩大了NEMD的研究范围.结果表明:随着拉伸或压缩应变的增加,BNNT热输运性能均呈降低的趋势.通过计算声子态密度(PDOS)在理论上分析了以上结果,发现在拉伸状态下,声子模式的变化是决定BNNT热输运性能变化的主要因素;在压缩状态下,热导率变化是由于模型发生明显的屈曲变形引起的.在低温段,BNNT的热输运性能受量子效应影响最初有一个线性增加的过程,当温度超过一定值时,其开始显著地降低;当BNNT长度小于120nm时,随着长度的增加,其弹道性能逐渐减弱,但仍主要体现为弹道特征,其热导率(κ)与长度(L)基本满足κ∝Lα这一关系.The Boltzmann-Peierls phonon transport equation（BTE）and non-equilibrium molecular dynamics simulation（NEMD）are used to investigate the thermal transport properties of boron nitride nanotubes（BNNTs）.First,the thermal-mechanical coupling is explored using NEMD.Then,by combining BTE and NEMD,the influence of temperature and length is investigated.Quantum correction is used to extend the range over which NEMD can be used.The results demonstrate that under low-strain conditions,the thermal conductivity decreases with increasing tensile or compressive strain.Then the phonon density of state（PDOS）is used to analyze the trends in thermal transport properties theoretically;it is found that the variations in thermal transport properties under tension are caused by changes in the phonon modes,and that under compression changes are induced by the flection of the BNNT structure.The BNNT thermal conductivity increases linearly with increasing temperature because of the quantum effect at low temperatures,and it decreases significantly as the temperature reaches a certain value.When the BNNT length is less than 120 nm,the BNNT？s ballistic characteristics weaken with increasing length,but it also performs ballistic characteristic mainly,and thermal conductivity（κ）and length（L）obey the relationshipκ∝Lα.

关 键 词：氮化硼纳米管 热输运性能 Boltzmann-Peierls声子传输方程 非平衡态分子动力学模拟 声子态密度 量子修正 

分 类 号：TB383.1[一般工业技术—材料科学与工程]