Synthesis Of Nanoparticles Embedded In SiO₂by Cu And Zn Ion Implantation And Their Thermal Stability In Different Annealing Atmosphere

Due to controlled energy and fluence, ion implantation is widely used insynthesis of nanocomposite. However, the properties of nanoparticles by ionimplantation are closely related to shape, size, composition and distribution, it makesa big challenge to optimize the material performance via control the nanoparticles.Dual ion implantation is an important method to control the composition ofnanoparticles. In this thesis, sequential implantation of Cu and Zn ions has beenemployed to synthesize nanoparticles (NPs). Moreover, the thermal stability of thesynthesized NPs under different annealing atmospheres has also been investigated.The main results and conclusions of the thesis are as follow:(1) Cu NPs embedded into SiO2were fabricated by implantation of45keV Cuions at a fluence of1.0×1017cm-2,and were then irradiated by Zn ions of50keV atthree different fluences, the distribution, structure and optical properties of thefabricated NPs were characterized in detail. After irradiated by Zn ions at low fluence,the surrounding dielectric environment of Cu nanoparticles has been changed by theformed Zn and Zn related composites, resulting in a significant increase of the Cusurface plasmon resonance (SPR) intensity. Cu-Zn alloy NPs have been fabricated bythe followed Zn ion implantation at fluence of0.5×1017cm-2. However, increasing theirradiation fluence of Zn ion to1.0×1017cm-2leads to removal of the Cu NPs owingto Zn post implantation induced sputtering erosion.(2) SiO2samples were sequentially implanted with45keV Cu ions at fluence of0.5×1017cm-2and50keV Zn ions at fluence of0.5×1017cm-2, then were subjected tothermal annealing in different atmospheres, i.e. oxygen and nitrogen atmospheres,respectively. The dependence of NPs formation and evolution on annealingatmosphere has been emphasized. Our results demonstrate that under nitrogenannealing atmosphere, Cu-Zn alloy NPs undergo the alloy and dealloy process. Under350°C annealing, alloy process occurrs. After400°C annealing, Cu-Zn alloy NPsbegin to decompose, increasing annealing temperature to500°C, Cu-Zn alloy NPshas been totally dealloyed, leaving only Cu nanoparticles. Under annealing in oxygenatmosphere, after400°C annealing, Zn atoms are extracted from alloy nanoparticlesand react with O2molecules, and thus, ZnO and Cu NPs appear in the substrate. Further increase of annealing temperature to550°C could transform all the Zn and Cuinto ZnO and CuO.(3) In addition, our results also demonstrate that the introduction of Zn into SiO2substrate could effectively suppress oxidation of Cu NPs under annealing in oxygenambient. It has been also found that the suppressing effect has been found to beenhanced with increasing the Zn concentration. Moreover, the existence of Cu couldpromote thermal diffusion of Zn towards substrate surface, which could result information of ZnO at relatively low temperature.