期刊
CHINESE PHYSICS B
卷 24, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1674-1056/24/2/026501
关键词
transition metal dichalcogenide; thermal expansion; phonon
资金
- National Natural Science Foundation of China [11274280, 11104254]
- National Basic Research Program of China [2012CB921300]
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 monolayerMX(2) (M=Mo andW; 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.
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