Experimental study of nanomechanical properties of 2-D transition metal dichalcogenides

In this study, nanoindentation was used to measure the nanomechanical properties of four two-dimensional transition metal dichalcogenides (TMDCs), namely, Molybdenum Disulfide (MoS2), Rhenium Disulfide (ReS2), Rhenium Diselenide (ReSe2), and Tungsten Diselenide (WSe2). An atomic force microscope (AFM) capable of measuring the nanomechanical properties of these two-dimensional nanomaterials through nanoindentation was used to generate force-distance curves for analysis. From the force-distance curves, reduced Young’s modulus, stiffness, and nanohardness of each of these nanomaterials were determined and compared between each other and existing data. The values obtained for reduced Young’s modulus of MoS2, ReS2, ReSe2, and WSe2 were 143.93, 78.57, 37.06, and 37.94 GPa, respectively. Among the samples, MoS2 has the highest values for its reduced Young’s modulus, stiffness, and nanohardness followed by, in order, ReS2, WSe2, and ReSe2. The values of reduced Young’s modulus obtained for these four samples were in agreement with theoretical calculation.