Effects of in-plane stiffness and charge transfer on thermal expansion of monolayer transition metal dichalcogenide  

作　　者：王占雨 周艳丽 王雪青 王飞 孙强 郭正晓 贾瑜 

机构地区：[1]International Joint Research Laboratory for Quantum Functional Materials of Henan,Zhengzhou University [2]School of Physics and Engineering,Zhengzhou University [3]Department of Mechanical and Electrical Engineering,Henan Industry and Trade Vocational College [4]Department of Chemistry,University College London

出　　处：《Chinese Physics B》2015年第2期343-349,共7页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11274280 and 11104254);the National Basic Research Program of China(Grant No.2012CB921300)

摘　　要：The temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconducting transition metal dichalcogenides.Unlike the corresponding bulk material,our simulations show that monolayer MX2（M = Mo and W;X = S,Se,and Te） exhibits a negative thermal expansion at low temperatures,induced by the bending modes.The transition from contraction to expansion at higher temperatures is observed.Interestingly,the thermal expansion can be tailored regularly by alteration of the M or X atom.Detailed analysis shows that the positive thermal expansion coefficient is determined mainly by the in-plane stiffness,which can be expressed by a simple relationship.Essentially the regularity of this change can be attributed to the difference in charge transfer between the different elements.These findings should be applicable to other two-dimensional systems.The temperature dependence of lattice constants is studied by using first-principles calculations to determine the effects of in-plane stiffness and charge transfer on the thermal expansions of monolayer semiconducting transition metal dichalcogenides.Unlike the corresponding bulk material,our simulations show that monolayer MX2（M = Mo and W;X = S,Se,and Te） exhibits a negative thermal expansion at low temperatures,induced by the bending modes.The transition from contraction to expansion at higher temperatures is observed.Interestingly,the thermal expansion can be tailored regularly by alteration of the M or X atom.Detailed analysis shows that the positive thermal expansion coefficient is determined mainly by the in-plane stiffness,which can be expressed by a simple relationship.Essentially the regularity of this change can be attributed to the difference in charge transfer between the different elements.These findings should be applicable to other two-dimensional systems.

关 键 词：transition metal dichalcogenide thermal expansion PHONON 

分 类 号：O469[理学—凝聚态物理]