Preparation And Properties Of In₂O₃ Quantum Dots In Glass Matrix

Recently, semiconductor quantum dots(QDs) have attracted much attention, because of their unique size-dependent properties and flexible chemical processability. However, in addition to biological applications, most of the envisioned applications aren’t based on single-particle QDs or their solutions. Hence, stably doping QDs in a favourable matrix or embedding to solid-state three-dimensional materials and retaining the inherent properties of individual QDs are extremely challenging.In2O3, as a promising metal oxides which have been commercially exploited for the applications of photonics technology, due to their fascinating chemical and physical properties. In this thesis, the porous transparent silica glassy matrix and Na2O-B2O3-Bi O2 glass uniformly doped with In2O3 quantum dots have been prepared by a sol-gel method plus a controlled atmosphere, the corresponding morphology and microstructure were studied through a variety of characterization methods. The photocatalytic activity and nonlinear optical properties of the as-prepared products were also measured by adopting photocatalytic instrument and Z-scan technique. The main contents are listed as follow:(1) The preparation of silica glassy matrix loaded with various concentrations(1 wt% and 3 wt%) monodisperse In2O3 precursors is performed through sol-gel method by using Tetraethyl orthosilicate(TEOS), Indium nitrate as precursors. Then, the samples are sintered by using atmosphere control methods to generate the In2O3 nanocrystals growth inside the deep volume of the silica matrix. TEM and XRD characterization confirmed that the NCs possess a cubic In2O3 crystal structure. The mean diameter of the obtained In2O3 nanocrystals increases with an increasing amount of precursors in the silica matrix. Photocatalytic activity of the products is also measured, and the result shows that the photodegradation of Rh B solution under UV irradiation in the presence of silica glassy matrix doped 1 wt% and 3 wt% In2O3 NCs were ~35.5% and ~61.6%, which is about two-fold and four-fold higher on photodegradation efficiency than pure silica glassy matrix.(2) In2O3 quantum dots doped in Na2O-B2O3-Bi O2 glass by the same preparation process through the sol-gel method by using Tetraethyl orthosilicate(TEOS), boracic acid(H3BO3) 、 metallic sodium(Na) as precursors, and the corresponding microstructure was studied by XRD and EDX. We have investigated the nonlinear optical properties of In2O3 quantum dots doped glass using Z-scan technique. Third-order nonlinear optical susceptibility χ(3) of the glass doped 1.5 wt% In2O3 quantum dots was estimated to be 4.23×10-11 esu,which has been significantly improved by doping In2O3 QDs. In particular, on the basis of our group research works before, a mechanism for the formation of In2O3 QDs glass is proposed.