Synthesis And Optical Properties Of Nanoparticles By Dual Ion Implantation Of Cu/Zn And Cu/Ti In SiO₂

Owing to the special optical,magnetic and electrical properties,the nanocomposites are widely used in optoelectronic devices,biosensors and photoswitch,etc.Among those synthesis methods of the nanocomposites,the ion implantation has attracted more and more attention because of its advantages,including various elements,controlled energy and fluence.Dual ion implantation can even be used to synthesize alloy nanoparticles（NPs）.In this thesis,the sequential ion implantation of Cu and Zn ions and sequential ion implantation of Cu and Ti ions into SiO₂ have been adopted to synthesize Cu-based alloy NPs.Then,the thermal stability and optical properties of the synthesized alloy NPs annealed in N₂ atmospheres at different temperatures have also been investigated.The main contents and results are discribed below:（1）Amorphous SiO₂ slices were sequentially implanted with 100 keV Cu ions at fluence of 5.0×10¹⁶ ions/cm² and 65 keV Zn ions at fluence of 5.0×10¹⁶ ions/cm²,and were then subjected to thermal annealing at different temperatures in N₂ atmosphere.The synthesis of Cu-Zn alloy NPs,thermal stability and optical properties were investigated.A absorption signal appears at 520 nm and Cu-Zn alloy NPs are formed in the as-implanted sample.The SPR intensity of the alloy NPs is strongest after annealing at 700 ℃.Alloy NPs are decomposed after annealing at 800 ℃,accompanied with formation of ZnSiO4 due to the diffusion of Zn and reaction with SiO₂ substrate.Cu NPs are formed after reaggregation.As the temperature rises,the Cu-Zn alloy NPs grow larger.Cu and Zn NPs are completely incorporated into alloy NPs.The Cu-Zn alloy NPs of good thermal stability were achieved.The Z-scan results show that the third-order nonlinear optical susceptibility of the as-implanted sample and the sample after annealing at 700 ℃ is much higher than the sample after annealing at 800 ℃.（2）The synthesis of Cu-Ti alloy NPs and thermal stability were discussed after sequential implantation of Cu ions(70 keV,5.0×10¹⁶ ions/cm²)and Ti ions(40 keV,5.0×10¹⁶ ions/cm²),Cu ions(100 keV,5.0×10¹⁶ ions/cm²)and Ti ions(50 keV,5.0×10¹⁶ ions/cm²)into SiO₂ with being subsequently annealed in N₂ atmosphere.Only Cu NPs exist in the as-implanted sample.Cu-Ti alloy NPs appear after being annealed at 600 ℃.The Cu NPs disappear and the absorption shoulders appear in the ultraviolet region after being annealed at 800 ℃.The absorption intensity from Cu-Ti alloy NPs slightly increases after being annealed at 900 ℃.The Cu-Ti alloy NPs exist as Cu4 Ti and CuTi accompanied with the impurities of TiSiO4 and TiO2.（3）By comparing Cu/Zn dual ion implatation with Cu/Ti dual ion implatation,the Cu/Zn of high miscibility,negtive heats of mixing and high interdiffusion coeffcient can be more easily combined to form alloy.While Ti of low electronegativity is chemically acvtive and can react with SiO₂ which leads to a complicated Cu-Ti system with impurities.