Structure Design And Fabrication Of Composite Nanoparticles

Recently,compound nanoparticles have been attracting great interest due to their unique physical and chemical properties.It is fundamental and necessary to study the relationship between the microstructures and related physical and chemical properties of compound nanoparticles.In this thesis,firstly,the interplay between the strain distribution and the growth parameters of the Ge/Ge O₂ core/shell nanoparticles was systemically investigated.After that,a simple approach was successfully developed for the formation of high density Au-Ag alloy nanoparticles using the modified pulsed laser deposition method and rapid thermal annealing technique.The following achievements were obtained:1.Strain distribution of confined Ge/Ge O₂ core/shell nanoparticles engineered by growth environments,a finite element?FE?calculation is performed to simulate the strain distribution of Ge/Ge O₂ core/shell nanoparticles confined in Al2O₃?Lu2O₃ and Si O₂ matrix grown by surface oxidation,The simulated results demonstrated that the strains at the Ge core and the Ge O₂ shell strongly depend on the growth environments of the nanoparticles,Moreover,it can be found that there has a transformation of the strain on Ge core from tensile to compressive strain during the growth of Ge/Ge O₂ core/shell nanoparticles,and the transformation of the strain is closely related with the Young's modulus of surrounding materials,The simulation results offer an effective method to manipulate the strain distributions of the confined Ge/Ge O₂ core/shell nanoparticles by tuning the growth environments,which can further have significant influences on the surface states and optical properties of Ge/Ge O₂ core/shell nanoparticles.2.Au-Ag alloy nanoparticles confined in Al2O₃ matrix were fabricated using PLD method.HRTEM and XPS analysis clearly reveal that Au-Ag alloy with the concentration of Au/Ag ratio of about 1:1 are fabricated in the insulating Al2O₃ matrix.Interestingly,the Au-Ag alloy nanoparticles exhibit a distinct PL band.The findings provide a physical insight and useful methodology to synthesize metallic alloy nanoparticles for potential application in photonic devices.