h-BN各向异性热膨胀和热输运特性的第一性原理研究 |
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作者姓名: | 牛波 钟李祥 郝伟 杨治华 段小明 蔡德龙 何培刚 贾德昌 李述周 周玉 |
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作者单位: | Institute for Advanced Ceramics;School of Materials Science and Engineering |
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基金项目: | the National Natural Science Foundation of China(51621091,51225203,and 51672060);the National Key Research and Development Program of China(2017YFB0310400)。 |
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摘 要: | 热填料的热膨胀系数和热导率是设计热管理和热防护复合材料的关键参考因素.六方氮化硼(h-BN)由于其独特的优点是最常用的热填料之一.但由于不同测试方法和测试样品的不一致性,其热膨胀系数和热导率的精确数值尚不清楚.本文分别用基于密度泛函理论的准谐近似方法和声子玻耳兹曼输运方程理论精确计算了h-BN沿层间和层内方向的热膨胀系...
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关 键 词: | 热膨胀系数 六方氮化硼 密度泛函理论 各向异性 玻耳兹曼 体积模量 不一致性 物理原理 |
First-principles study of the anisotropic thermal expansion and thermal transport properties in h-BN |
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Authors: | Bo Niu Lixiang Zhong Wei Hao Zhihua Yang Xiaoming Duan Delong Cai Peigang He Dechang Jia Shuzhou Li Yu Zhou |
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Affiliation: | (Institute for Advanced Ceramics,School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150080,China;School of Materials Science and Engineering,Nanyang Technological University,Singapore 639798,Singapore) |
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Abstract: | The thermal expansion coefficient(TEC)and thermal conductivity(k)of thermal fillers are key factors for designing thermal management and thermal protection composite materials.Due to its unique advantages,hexagonal boron nitride(h-BN)is one of the most commonly used thermal fillers.However,its TEC and k values are still unclear due to the inconsistency of characterization techniques and sample preparations.In this work,these disputes were addressed using the quasi-harmonic approximation(QHA)method and phonon Boltzmann transport equation(BTE)theory based on the density functional theory(DFT),respectively.The accuracy of our calculated TEC and k values was confirmed by previously reported experimental results,and the underlying physical principles were analyzed from the phonon behaviors.Our TEC results show that the h-BN has small in-plane negative value and large cross-plane positive value,which are-2.4×10-6 and 36.4×10-6 K-1 at 300 K,respectively.And the anisotropic TEC is mainly determined by the anisotropic isothermal bulk modulus and the low-frequency out-of-plane longitudinal phonon modes.We found that the convergence of cutoff radius and q-grid size have significant effect on the accuracy of k of h-BN.Our results show that the in-plane k is much higher than the cross-plane k,and the values at 300 K are 286.6 and 2.7 W m-1 K-1,respectively.The anisotropic phonon group velocity arising from the vibration behaviors of acoustic phonon modes should be primarily responsible for the anisotropic k.Our calculated TEC and k values will provide important references for the design of h-BN composite materials. |
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Keywords: | h-BN thermal expansion coefficient thermal conductivity phonon behaviors density functional theory |
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