The Deformation-Induced Phase Transformation in Gold Nanoribbons

The tensile experiment for nanomaterials in a transmission electron microscope (TEM) has become a very important tool to study the atomic deformation of material at nanoscale. An enormous amount of effort has been spent to perform the tensile experiments on nanomaterials. They revealed new discoveries that have never been observed in bulk materials and eventually lead to further applications. In this thesis, experimental reports of tensile test on gold nanoribbons in TEM were reported. The gold nanoribbons have 4H structure but the FCC structure could coexist in some areas. Gold nanoparticles have been studied intensively in the past decades due to their extraordinary properties and promising applications. The rise of chemical syntheses technology has stimulated further exploration of gold nanoparticles in recent years. The wet chemical technique has successfully created more closed-packing structures that have never been discovered before, including 4H gold nanoribbons. Even though the latest syntheses techniques have created many interesting structures, the investigation of their mechanical properties seems to be very difficult to perform. The tensile experiment on gold nanoribbons has never been performed. This thesis reports the first investigation of the mechanical properties of gold nanoribbons by using tensile test in TEM. Phase transformation from 4H to FCC or vice versa were observed. The dislocation in the structures leads to the phase transformation. Furthermore, necking has also been observed during tensile test, particularly in the FCC structure which eventually lead to ductile fracture. However, necking was also observed in 4H structure. In addition to this, coalescence between two nanoribbons was also observed during tensile