MECHANICAL AND THERMAL PROPERTIES OF TWO-DIMENSIONAL MATERIAL
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University of North Carolina at Charlotte
The aim of this dissertation is to investigate the mechanical and thermal propertiesof two-dimensional materials. The discovery of the fantastic properties of graphene,such as high mechanical strength and excellent electronic properties, has stimulatedinterests in exfoliating other two-dimensional graphene-like materials. Laminatedmaterials such as hexagonal boron nitride or MoO3 which are composed of stackedlayers with the van derWaals force between adjacent sheets and strong covalent bondswithin each layer have received the most attention. In laminated materials, the weakbonding between layers allows an easy isolation of free-standing single or few-atomthicksheets. The isolated stable free-standing sheets are known as two-dimensionalmaterials which exhibit properties distinct from their corresponding three-dimensionalbulk material counterparts.The high specic surface area of two-dimensional materials along with their attractivephysical, electrical and mechanical properties make them important for avariety of applications such as supercapacitors, optoelectronics, spintronics, lithiumion batteries, sensors and nanocomposites. The use of two-dimensional materials insuch sensitive devices necessitates a fundamental understanding of their physical andmechanical properties. It is the objective of this dissertation to investigate the mechanicaland thermal properties of two-dimensional materials with special focus onMoO3, graphyne and hybrid graphene-boron nitirde.Ideally, the properties of two-dimensional materials should be characterized experimentally.However, designing and performing experiments at nanoscales is verycomplicated. Computational studies, on the other hand, can provide valuable insightsabout the behavior of two-dimensional materials. In this dissertation density functionaltheory (DFT) and molecular dynamics (MD) simulations are used to studythe properties of two-dimensional materials. In the rst part of this dissertation,DFT is used to develop and propose a hyperelastic constitutive model for modelingthe mechanical behavior of MoO3. Such a constitutive model pave the way towardnite element modeling of monolayer MoO3 and can substantially reduce the computationalcosts in comparison with atomistic simulations. In the second part ofthe dissertation, molecular dynamics is utilized to study the mechanical and thermalproperties of both graphyne and hybrid graphene-boron nitride nanoribbons. UsingMD simulations, the impacts of nanoribbons width, length and chirality on theirproperties are investigated. Furthermore, the eects of defects on the properties ofribbons are studied and the strain engineering of the thermal conductivity of ribbonsis investigated.
Smelser, RonaldCherukuri, HarishZhang, Jian
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2015.
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