Off-campus Michigan Tech users: To download campus access theses or dissertations, please use the following button to log in with your Michigan Tech ID and password: log in to proxy server
Non-Michigan Tech users: Please talk to your librarian about requesting this thesis or dissertation through interlibrary loan.
Date of Award
Campus Access Master's Thesis
Master of Science in Materials Science and Engineering (MS)
Administrative Home Department
Department of Materials Science and Engineering
Yun Hang Hu
Committee Member 1
Committee Member 2
Invention of graphene has motivated research community to investigate two dimensional materials, due to their exceptional set of electrical-mechanical properties. Molybdenum Disulfide (MoS2), a member of transition metal dichalcogenides (TMD), is found to be the most promising material for various electronic devices such as supercapacitors, optoelectronics, memristor, biosensors. Previously, researchers have demonstrated that 1T phase MoS2 possess superior electrical properties compared to its 2H phase form, due to enhanced electrical conductivity and hydrophilicity. There had been several attempts to understand the mechanism involved in the phase transformation, but use of different processes have provided varying results. In this research, a novel attempt was made to study phase and structural changes in MoS2 by solvent assisted mechanical milling process. The transformation of most stable 2H phase into metastable 1T phase was studied by varying milling duration in presence of different solvents i.e. deionized water (H2O) and dimethylformamide (DMF). A quantitative and qualitative analysis of the phase transformation process was performed by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS) characterizations. The results have shown that both solvents support 2H to 1T phase transformation with increasing milling duration, but the transformation is faster and more effective in a presence of H2O as compared to DMF. This observation can be primarily attributed to polarity difference that each solvent molecule possess. Both of the solvents under investigation are polar in nature where water molecule possess higher polarity compared with dimethylformamide molecule. Intercalation of the solvent molecules impart varying magnitudes of attractive forces on adjacent layers of the two dimensional material, causing dynamically shrink or expand.
Soman, Prasad Pramod, "Mechanically Induced Structural Changes in Molybdenum Disulfide", Campus Access Master's Thesis, Michigan Technological University, 2016.