Fabrication and characterisation of silver-glass nanocomposites
Metallic nanoparticles and nanostructures have spawned significant interest in a wide area of science. Nanoparticles in glass show unique linear and nonlinear optical properties due to surface plasmon resonances. These induce absorption and scattering of light around the resonance wavelength, which can be tuned by changing size, shape or spatial distribution of the nanoparticles. Metallic nanostructures show local field enhancement effects, which are used for example in surface enhanced Raman scattering. Their large surface area compared to bulk materials makes them interesting for applications in chemistry and life science. In this thesis the synthesis of two different types of silver-glass nanocomposites is investigated. Both materials are prepared from silver ion-exchanged glass, which is also prepared and characterised in house. The first type of nanocomposite is glass doped with silver nanoparticles. It is formed by annealing silver ion-exchanged glass at a temperature close to the transition point. This induces the reduction of silver to atoms and the agglomeration in nanoparticles with a diameter of less than 10nm, which are located in a layer beneath the glass surface, which has a thickness of tens of micrometres. These nanoparticles are responsible for a characteristic absorption band centred around 410nm due to plasmon resonances. The second nanocomposite, which was first produced in the course of this work, is called glass-silver composite. It is created by pulsed laser irradiation of silver ion-exchanged glass. It contains nanoparticles with a diameter of 100nm or more, which are distributed homogeneously in a dense single monolayer at the glass surface. This material shows a strong metal-like reflection of light. The location of nanoparticles at the surface makes it interesting for applications utilising the field enhancement effect of the nanoparticles, such as surface enhanced Raman scattering and enhancement of light conversion. Both nanocomposites and the ion-exchanged glass are characterised by optical microscopy, scanning electron microscopy and optical spectroscopy. The work is divided in four chapters, starting with an introduction in chapter 1. In chapter 2 the method of production of the silver ion-exchanged glass and the properties of the material are presented. Generation of nanoparticles inside the glass by annealing is covered in chapter 3 and an analysis of laser processing of ion-exchanged glasses is shown in chapter 4. The concluding chapter consists of a summary of the work and an outlook.
Networked Digital Library of Theses and Dissertations