Microstructures And Upconversion Luminescence Properties Investigations On Er³⁺ Doped SiO₂-PbF₂-PbO Transparent Glass Ceramics

Rare-earth-doped materials have been extensively investigated because of the promising application in the all-solid-laser, optical communications,etc,recently. And rare earth ions doped oxyfluoride glass ceramics,multi-phase materials with fluoride nanocrystalline in the oxide glass,have attracted much more attention because they combine the lower phonon energy environment of heavy metal fluoride crystal with the better chemical, mechanical and thermal stability of oxide glasses.In this dissertation, the Er3+ doped SiO2-PbF2-PbO glass ceramics were prepared by high temperature sintering method. The influence of different preparation parameters, different matrix composition and different rare earth compounds on microstructure and optical properties of the glasses and glass ceramics were discussed detailed based on the experimental measurement results of differential scanning calorimetry(DSC), X-ray diffraction(XRD), absorption spectra and luminescence spectra.Firstly, the 50SiO2-20PbF2-30PbO-0.5ErF3 glass and glass ceramic were prepared. Because of the reaction SiO2+2PbF2→SiF4↑+2PbO, the composition of PbF2 will decrease during the sintering. To prevent from severe loss of PbF2, the preparation parameters should be optimized. We suggest that when the powder was sintering at 1000℃, the sintering time is about 15min. In order to obtain the ideal size and content of nanocrystals, the heat treatment temperature should be at a temperature about 25℃higher than their glass transition temperature(Tg). It is verified by the XRD analysis that the crystal phase in glass ceramics isβ-PbF2, and the sizes of the precipitated crystallites were evaluated to be 12nm. The intensity of upconversion luminescence in the glass ceramics enhanced drastically compared to that in the precursor glass.Based on the above preparation parameters, four different erbium compounds: Er2O3, ErOF, ErF3 and ErCl3 doped SiO2-PbF2-PbO oxyfluoride glass ceramics were prepared. The results indicated that theΩ2 values of the glass ceramics are much smaller than that of their precursor glasses due to concentration of Er3+ ions into PbF2 nanocrystals after heat treatment. Furthermore, the glass ceramics doped with ErCl3 has the lowest transparency among all. While, the glass ceramics doped with ErF3 was the most beneficial for the precipitation of PbF2 crystallites and had the lowest ratio of red to green emission.To investigate the influence of content of PbF2, the ErF3 doped 50SiO2-xPbF2-(50-x)PbO-0.5ErF3 glass and glasses ceramics were prepared. It was concluded that with the increase of PbF2 content, the ratio of the red to green upconversion luminescence decreased which caused by the decrease of the Er3+ concentration inside the nanocrystallites.