Date of Graduation

5-2013

Document Type

Thesis

Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor

Spearot, Douglas E.

Reader

Huang, Po-Huang Adam

Abstract

Molybdenum disulfide (MoS2) has a lamellar crystal structure, which makes it ideal for use as a solid lubricant. Transmission electron microscope (TEM) images have shown that line defects exist within the lattice of mechanically deformed MoS2, but the physical mechanisms which lead to the formation of these defects are unknown. The two central objectives of this research are to use molecular dynamics simulations to study the effects of tensile deformation on both single layer and bulk MoS2 and explore the properties of line defects in an otherwise perfect lattice of MoS2. Under tensile loading, molecular dynamics simulations show a multi-stage stress versus strain diagram. Atomistic visualization shows a distinct change in the structure of the lattice during tensile stretching. This new structure is likely the result of a phase transformation. For the second objective, a series of computational approaches are used to create a single line defect in a perfect MoS2 lattice. Shearing both parallel and perpendicular to the basal plane of MoS2 and compression leading to buckling were unsuccessful in moving the line defect.

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