The Regulation Of The Interlayer Potential Of Two-dimensional Materials And The Mechanical Study Of The Interface Dislocation Structure

Dislocations are one of the most fundamental concepts in materials science,two-dimensional material provides a new system for studying dislocations.When a relative twist angle or lattice mismatch between differernt layers appears in the heterojunction,the dislocation could be formed by the competition between the interlayer potential and tensile stiffness of two-dimensional material.The formation of dislocation has induced a lot of new physical properties.In addition,the formation of interface dislocations is accompanied by the coexistence of various stacking configurations.The formation of dislocations has a strong relationship with the interlayer potential.Chemical modification and external force are the effective means to control the interlayer potential and electronic property.Therefore,we studied the effects of chemical modification and external forces on the interlayer potential of the system,and the influence of stacking configuration on electronic properties was also studied.The effect of chemical modification on the properties of the system includes two parts.In the first part,we studied the properties of graphene and copper(111)after hydrogenation and hydroxylation by the first principles.It was found that hydrogenation and hydroxylation can effectively immobilize graphene on copper(111).This was due to the strong interfacial coupling between chemically modified graphene and copper(111),and strong interfacial coupling was also beneficial to increase the platinum atoms loading on graphene;In the second part we studied the properties of bilayer graphene and graphene/boron nitride after hydrogenation or fluorination,the result showed that hydrogenation and fluorination could change the interlayer potential.Then we studied the effect of stacking configuration on the electronic properties of hydrogenated graphene/boron nitride.The influence of external forces on the nature of the system includes two parts.In the first part,we found that the rate of change of the band gap of the bilayer heterojunctions constructed by transition metal sulfides dependended on stacking configurations as interlayer distances decreased,and we proposed a plan to prepare the properties that semiconductor and metal states could coexist in the small system.In the second part,the interlayer potential of boron nitride/molybdenum disulfide and graphene/molybdenum disulfide had been calculated by density functional theory.The results showed that boron nitride/molybdenum disulfide and graphene/molybdenum disulfide both had the characteristics of high stacking fault energy.As the interlayer distances decreased,the characteristics of high stacking fault energies remained unchanged.The band gap of molybdenum disulfide in graphene/molybdenum disulfide did not depend on interlayer distance,but the band gap of molybdenum disulfide in boron nitride/molybdenum disulfide did depend on it.However,the stacking configuration had little effect on the band gap of molybdenum disulfide in the boron nitride/molybdenum disulfide and graphene/molybdenum disulfide at the same interlayer distance.Subsequently,we investigated the effect of neighboring layers by comparing the differences of interlayer potential between trilayer heterostructures(graphene/graphene/graphene,graphene/graphene/boron nitride,boron nitride/graphene/boron nitride)and bilayer heterostructures(graphene/graphene,graphene/boron nitride)using density functional theory.It was found that the neighboring layer had a great influence on the interlayer potential of the adjacent layer,and the value of the variation depended on the properties of the adjacent layer.In addition,a new simple expression is proven to describe the general stacking fault energy of graphene-like structure with high accuracy.Finally the generalized Peierls-Nabarro model was used to discuss the influence of the change of interlayer potential on the dislocation.