Time-resolved photoluminescence studies in Eu-doped SiO2 - HfO2 - ZnO glass-ceramic waveguides

Fabrication of ZnO-HfO2 hybrid nanocrystals embedded 70 SiO2-(30−x) HfO2-xZnO (x=0, 2, 5, 7 and 10 mol%) ternary glass-ceramic planar waveguides doped with 1 mol% Eu-ions, by sol-gel process and dip-coating technique has been reported. The effect of varying ZnO concentration on the growth and structural evolution of ZnO-HfO2 hybrid nanocrystals were investigated using transmission electron microscopy and other spectroscopic tools. Time-resolved PL measurements were performed to estimate the PL emission lifetimes of Eu2+ and Eu3+, present in two different local environments in the ternary matrix, as a function of ZnO concentration. Eu3+ ions exhibit double exponential decay profile for the D05→F27 emission, while the decay curves of Eu2+ ions are single exponential. The variations in the PL emission decay profiles are used as a probe to investigate the changes in the local environments of the rare-earth ions in the glass-ceramic waveguides.