Nanoscale Structure and Energy Dissipation Behaviour of Tungsten Disulphide and Gold Nanoparticles and Nanoclusters Investigated by Advanced Microscopy Techniques

Abstract: In this study nanoscale structure and associated energy dissipation behavior of nanoparticulates of tungsten disulphide (WS2) and nanoparticles of gold (Au) were investigated by advanced scanning probe and electron microscopy techniques. WS2 nanoparticulates were deposited on silicon substrate by van der Waals adhesion transfer-deposition mechanisms. The templates of three size variants of Au nanoparticles, close packed (4-6nm), well dispersed (120-150nm) and clusters of (120-150 nm) nanoparticles were prepared on silicon substrates. Nano-microstructure, morphology, topography and phase shift of both WS2 and Au nanoparticles and nanoparticulates were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). SEM and TEM observations showed that the nanoparticulates of WS2 are atomically oriented lamellar-hexagonal structure or inorganic graphite like structure. In the tapping mode AFM imaging, repeated scanning of nanoparticulates of WS2 resulted in inter layer movement of nanolayers. It was observed that cluster of Au nanoparticles caused more phase shift and high energy dissipation compared to that of well dispersed Au nanoparticles, however close packed Au nanoparticles caused lowest phase shift and energy dissipation. Nano-microstructure, morphology, topography and phase shift were analyzed by SXM software. The nanoscale studies showed that the phase shift and the energy dissipation were influenced by the geometrical and mechanical gradient of the samples.