SiO2:Pr3+-Ce3+ phosphor powders were successfully prepared using a sol-gel process. The concentration of Pr 3+ was fixed at 0.2 mol% while that of Ce3+ was varied in the range of 0.2-2 mol%. High resolution transmission electron microscopy (HRTEM) clearly showed nanoclusters of Pr and Ce present in the amorphous SiO2 matrix, field emission scanning electron microscopy (FE-SEM) indicated that SiO2 clustered nanoparticles from 20 to 120 nm were obtained. Si-O-Si asymmetric stretching was measured with Fourier transform-IR (FT-IR) spectroscopy and it was also realized that this band increased with incorporation of the activator ions into the SiO2 matrix. The broad blue emission from the Ce3+ ions attributed to the 5d 1-4f1 transition was observed from the SiO2:0.2 mol% Pr3+-1 mol% Ce3+ phosphor. This emission was slightly enhanced compared to that of the singly doped SiO2:1 mol%Ce3+ phosphor. Further investigations were conducted where the CL intensity was measured at different beam voltages and currents from 1 to 5 kV and 8.5 to 30 μA, respectively, in order to study their effects on the CL intensity of SiO2:0.2 mol% Pr3+-1 mol% Ce3+. The electron-beam dissociated the SiO2 and as a result an oxygen-deficient surface dead or non-luminescent layer of SiOx, where x < 2 on the surface, was formed. © 2010 Elsevier B.V. All rights reserved.
Mhlongo, G. H., Ntwaeaborwa, O. M., Dhlamini, M. S., Swart, H. C., & Hillie, K. T. (2011). Effects of Ce3+ concentration, beam voltage and current on the cathodoluminescence intensity of SiO2:Pr3+-Ce3+ nanophosphor. Journal of Alloys and Compounds, 509(6), 2986–2992. https://doi.org/10.1016/j.jallcom.2010.11.179