In Situ Mechanical Measurement Of Nanomaterials By SEM/SPM Hybrid System

Nanomaterials show many different electrical, mechnical and magneticproperties comparing to their bulk forms. These special properties is one of thehot issues for the present research of nanomaterials. As one of the fundamentalcharacteristics, the research of mechanical properties of nanomaterialshas important significance. Nanomaterials will deform under external force.Once their shapes deform, their electrical and magnetic properties will changecorrespondingly. Fully understand and know the mechanical properties ofnanomaterials, is good for their excellent performance. But, as the scale ofnanomaterials are so small, it is very difficult to manipulate them. It hinder themechanical properties research of nanomaterials.The mechanical properties of polycrystalline TiO2nano/microspheres andsingle crystal Si3N4nanowires with different diameters were characterized withnanoindentation, tensile and three point bending methods in this essay.Meanwhile, the relationship between mechanical properties of nanomaterialsand their diameters were also discussed. The results observed from experimentswere investigated. The research details are shown as follow.1. TiO2nano/microspheres with different diameters were characterized by nanoindentation method with SEM/SPM hybrid system. The process of thenanoindentation was reproduced by finite element ansys method. Thedeformation of the nano/microsphere can be observed clearly and the calculationmethod of nanoindentation can be revised with the help of finite element model.2. Elastic modulus of TiO2nano/microspheres were calculated by revisedcalculation method. It shows that there is no clear relationship between theelastic modulus and diameters of TiO2nano/microspheres. The elastic modulusof TiO2nano/microspheres is30%higher comparing to their bulk forms and theprobably reason for this was analyzed. Then the results were taken into the finiteelement model. The revised calculation method is validated.3. As the SEM/FIB hybrid system has the functions of nano manipulationand2D,3D nano characterization, it was used to build in situ tensile experimentplatform with the AFM tip. Single crystal Si3N4nanowires with differentdiameters were characterized with this in situ tensile experiment platform.Elastic modulus and breaking strength were calculated out. The results show thatthe elastic modulus will decrease with the increased diameters when theirdiameters between80nm to140nm. The inner reason for the size effect wasinvestigative.4. Single crystal Si3N4nanowires with different diameters werecharacterized by three point bending tests with SEM/SPM hybrid system. Thebending modulus and bending strength were calculated out. The results showthat the bending modulus of Si3N4nanowires is40%higher comparing to their bulk forms and their bending strength also bigger than their bulk forms. Thereason for these phenomenon was investigative. Furthermore, the elasticmodulus calculated by these two different method were compared and analyzed.