MgO 中对称倾斜晶界热传递的原子机制,Acta Materialia

当前位置： X-MOL 学术 › Acta Mater. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

MgO 中对称倾斜晶界热传递的原子机制
Acta Materialia ( IF 8.3 ) Pub Date : 2019-06-01 , DOI: 10.1016/j.actamat.2019.04.009
Susumu Fujii , Tatsuya Yokoi , Masato Yoshiya

摘要晶界通常对多晶材料的宏观性质有决定性的影响，但其原子结构、界面长度和成分的多样性使其难以全面表征。理解晶界结构和性能之间的关系将极大地促进优质材料开发的一个不可或缺的例子是热传输，特别是在微观结构演变、热电和热障涂层方面。为了有助于更全面的理解，我们使用扰动分子动力学对 MgO 中各种对称倾斜晶界的晶格热传导进行了系统研究。发现热导率随晶界结构而显着变化，但与过量体积密切相关，过量体积是晶界平面附近原子数密度的量度。实空间分析表明，位错密度决定了低角度边界中的声子传输路径和热导率，而决定热导率的是开放体积的数量，而不是高角度边界中结构单元的形状。我们还发现，无论结构单元的形状如何，低角度边界主要减少低频声子传输，而高角度边界也有效减少中频和高频声子传输。这些见解有望适用于其他紧密堆积的氧化物系统，

"点击查看英文标题和摘要"

Atomistic Mechanisms of Thermal Transport across Symmetric Tilt Grain Boundaries in MgO

Abstract Grain boundaries often have a decisive effect on the macroscopic properties of polycrystalline materials, but the wide variety of their atomic structures, interfacial lengths, and compositions makes them difficult to characterize all-encompassingly. An indispensable example in which an understanding of the relationship between grain boundary structures and properties would greatly facilitate development of superior materials is thermal transport, especially with respect to microstructure evolution, thermoelectrics and thermal barrier coatings. To contribute to a more comprehensive understanding, we performed a systematic study of lattice thermal conduction across a wide range of symmetric tilt grain boundaries in MgO using perturbed molecular dynamics. It was found that thermal conductivities vary significantly with grain boundary structure but are strongly correlated with excess volume, which is a measure of the number density of atoms in the vicinity of the grain boundary planes. Real-space analysis revealed that dislocation densities determine the phonon transport paths and thermal conductivity in low-angle boundaries whereas it is the amount of open volume rather than the shape of structural units in high-angle boundaries that determine thermal conductivity. We also found that low-angle boundaries mainly reduce phonon transports at low frequencies whereas high-angle boundaries also reduce it at intermediate and high frequencies effectively, regardless of the shape of structural units. These insights are expected to be applicable to other close-packed oxide systems, and should aid the design of next-generation thermal materials through tailoring of grain boundaries.

更新日期：2019-06-01

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南