第34卷
第7-8期
2015年8月特约专栏
中国材料进展 MATERIALSCHINA
Vol. 34No.7 8
Aug.2015
维石墨烯/h-BN异质结构负热膨胀二年
性质的理论研究
武明义，孙强，贾瑜，梁二军
（郑州大学物理工程学院，河南郑州450001）
摘
要：二维材料由于存在“膜效应”，即在垂直于薄膜方向的热涨落，使得沿着二维薄膜面内方向出现反常的负热膨胀现
象。这种热效应对薄膜的稳定性及电子性质可产生重要影响。基于第一性原理计算和准谐近似，系统地研究了二维单层石重烯、h-BN和石墨烯/h-BN异质结构的电子、声子以及热影账性质，计算了3种结构不同振动模式的格林奈森参数，讨论了引起这3种结构负热膨胀的操动模式。计算表明，由于重直薄膜方向的热振动，石墨烯和-BN在薄膜面内均具有较大的负热膨
影响，使得形成的异质结构的负膨胀系数介于石量烯和-BN之间。通过分析异质结构的探动模式，发现引起面内热收缩的 ZA报动模式受到了层间范惩瓦尔斯相互作用影响，导致异质结构的负热膨胀系数大于石蛋烯面小于A-BN。研究表明，可以
在实验中通过范德瓦尔斯相互作用来改变层状结构材料的负热膨胀性质，从而提高薄膜材料结构和电子性质的热稳定性。关键词：石墨烯：h-BN；负热影账；格林奈森参数；范德瓦尔斯相互作用
中图分类号：0613.71；TB383
文献标识码：A
文章编号：16743962(2015)07051506
Study of Negative Thermal Expansion in2D
TheoreticalS
Graphene/h-BNHeterostructure WU Mingyi,SUN Qiang,JIA YU,LIANG Erjun
(College of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China)
AbstraCt: Two dimensional (2D) materials generally exhibit negative thermal expansion (NTE) along the in-plane di-rections due to the so called membrane effect", i. e. the thermal fluctuation in vertical direction. The thermal phenome-non may drastically impact the stability and electronic property of the low dimensional materials. Based on first-principles calculations and quasi harmonic approximation, electronic structures, phonon spectra and expansion property of the two di-mensional materials: graphene, h-BN sheet and graphene/h-BN heterostructure are systematically studied. The mode grineisen parameters are calculated and the vibrational modes which contribute to the NTE in the three systems are dis-cussed. The calculated results show that both graphenen and h-BN exhibit pronounced NTE in the in-plane directions due to the vertical thermal vibration, The graphenen/h-BN heterostructure is formed through van der Waals ( vdW) interaction between the monolayer graphene and the h-BN sheet, and this weak interaction may influence the vertical thermal vibration of the monolayer graphene and the h-BN sheet, and consequently the thermal contraction of the heterostructure is signifi-cantly smaller than that of the h-BN, but larger than the graphene. Our results indicate that NTE of the two dimensional materials can be altered through the vdW interactions in experiment and enhance the thermal stability of the structure and electronic property.
Key wOrds : graphene; h-BN; negative thermal expansion; grineisen parameter; van der Waals interaction
1前言
作为下一代电子材料，二维材料石墨烯和h-BN的
收稿日期：2015-04-09
第一作者：武明义，男，1985年生，博士研究生
强，男，1966年生，教授，Email：qsn@
通讯作者：孙
zzu, edu. cn
DOI: 10. 7502/j, issn. 1674 3962. 2015. 07. 04
潜在应用价值引起了人们极大的研究兴趣（1-4)，尤其是它们优异的电子性质【3.5-12]、热学性质【13-18]和力学性质[19-21]，使得这些单层二维材料成为当今纳米科学研究的明星材料。这种二维材料具有理想的蜂窝状排列结