Study On The Preparation And Optical Performance Of Ordered Structure Of Silver And Gold Nanoparticles

Nano-materials had many peculiar and fascinating properties in mechanics, electric magnetic,thermology,optics and chemical field,because of their basic properties of nanoparticles,such as surface effect,volume effect,quantum size effect and macroscopic quantum tunneling effect.The research and preparation of nanomaterials became a hot topic of the new times of science and technology.Reaearch on metal nano-materials,especially gold and silver metal nano-materials was always the focal point of scientists.There were many research reports about the controllable preparation and the assembly of gold and silver nanoparticles.However there were very limited results about the preparation and assembly of the ordered structure of gold and silver.For example,there were many reports on the preparation of glasses doped with gold and silver nanoprticles,but in these researches the nanoparticles only could be separated out on the surface or near the interface of block glass without spatial ordering.However,the ordered structure of gold and silver nanoparticles in the glass was necessary for opt-electronic integration,especially for all-optical integration technology.Moreover,metal nanomaterial had excellent optical properties due to the surface plasmon resonance.Especially in recent years,along with the confirmation of the surface enhanced Raman scattering effect and the fluorescence enhanced effect of gold and silver nanoparticles,the study of the performance and application of gold and silver nanoparticles had become a hot field of research.However,most research on the optical properties of it was focused on its morphology,size,fluorescein and emission field,while research on properties of the ordered structure of gold and silver nanoparticles was very limited.Basing on the current situation at home and abroad,the author firstly studied on the assembly of the ordered structure of gold and silver nanoparticles.After that,the optical properties of the ordered structure had been studied.The main results and conclusions of this dissertation were outlined as follows:1.With the diffusion theory and thermodynamics theory,the author had studied on the process of crystallization and reduction of the glass,and analyzed the stress of the glass during the stretching process.The ordered structure of silver nanoparticles arranged in the glass had been obtained.The microstructure of the glass samples was studied by FE-SEM.Silver nanorods had diameter of 50～100nm,length of 100～800nm.Corresponding technological parameters were outlined as follows:the heat treatment for crystallization was 615℃for 12h.The elongating temperature was 570℃.A stress of 75 kg was applied to the glass sample to draw at a rate of 120mm/min.The reduction was carried out at 430℃for 4h,and the hydrogen gas pressure was 0.25MPa.2.With the dry silver ion exchange and masking irradiation technology,the synthesis of silver cluster with ordered structure in the glass was studied.The experimental parameters of dry silver ion exchange were outlined as follows:1.5kV, 350℃,150min.The result showed that the silver ion could be injected into the glass by the dry silver ion exchange.The silver ion could be reduced and formed silver nucleus by UV irradiation.After the heat treatment and reduction,there was an indication of ordered arrangement of silver cluster formed in the glass.3.The optical absorption performance of the glass containing ordered structure of silver nanoparticles was calculated,contrastive analysis about the different structure of samples was done.The results showed that the polarizing performance parameters obtained from tests were consistent with the theoretical calculated results.The polarizing wavelength band of the glass sample was related to the distribution range of aspect ratio of the ellipsoid silver particles.Along with the increasing of distribution range,the band became broader.There should be two kinds of different configuration of silver nanoparticles involved in the polarization effect: one was the needle-like siver nanoparticles and another was the filament structure of silver.4.The third-order nonlinear optical properties of the glass samples were studied by Z-scan technology.The results showed that when the polarization of the laser was parallel to the elongation of the Ag nanorods,the nonlinear absorption coefficient and nonlinear refraction index reached their maximum values.At 780 nm,with a peak irradiance 1.9 GW/cm²,when the polarization of the light was perpendicular to the elongation of the Ag nanorods,the appropriate figures of merit W=1.6 and T=0.16 were obtained,which satisfied the requirement of W＞1 and T＜1 for all optical switching applications.5.By two-step anodization method,porous anodic alumina was prepared successfully,and the average diameter of the pores was about 60nm.The vitriol-phosphate-glycol system,which was adopted during the electrochemistry polishing of high purity aluminum patch,was studied.The factors that affect on ordered porous structure of AAO film were studied.The factors included the pretreatment technology,the oxidization voltage,duration time of secondary anodization and pore enlarging treatment.6.Au nanoparticles were loaded on porous alumina template surface by photoreduction technique,and spherical gold nanoparticles formed regular arrangement that was consistent with the pore structure of AAO.The UV-Vis optical absorption peak of the ordered structure of gold on the surface of AAO membrane was at 536nm,that was consistent with the absorption peak of the ideal sphere gold nanoparticles.By thermochemical reduction of titanium dioxide sol-gel system doped on glass substrate,sample of Au nanoparticles loaded on glass substrate was obtained. Test results showed that the optical absorption peak had a distinct red shift,this phenomena could be due to the change of the surface plasmons of Au nanoparticles caused by the TiO₂ crystal particles around it.Meanwhile,there was a distinct fluorescence emission at the wavelength of 633nm.With the contrastive analysis,the phenomena could be due to the change of the local electrical field of Au nanoparticles caused by the TiO₂ crystal particles around it.