The effect of Mg2+ ions on the photoluminescence of Ce3+-doped silica

In this paper, we report enhanced luminescence of Mg-co-doped silica gels, which were prepared by a sol-gel method. The total amount of Ce3+ ions was kept constant in this experiment at 0.5 mol% total doping. Structural, morphological, thermal, optical absorption and photoluminescence studies were employed. The XRD spectra show that all the samples are non-crystalline. Scanning electron microscopy (SEM) images show that the particles were in nano-range and spherical in shape. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) of samples depict that the presence of dopant and co-dopant decreases the endothermic peak temperature; while Ce3+ increase the yield, Mg2+ reduces it. UV analyses revealed that the presence of Ce3+ ions increases transmittance but lowers absorbance of annealed silica xerogels, while that of Mg2+ ions reduces transmittance but increases absorbance. Luminescence intensities were compared for different gels with and without Mg particles by varying the different concentrations of Mg. Silica containing Mg2+ ions had broad blue emission due to energy transfer from Mg2+ to Ce3+, which is due to radiative recombination. An increase in luminescence intensity was observed as the Mg2+ to Ce3+ ratio increased for the range investigated.