Effects of accelerating beam voltage on luminescence of Er3+ and Tm3+ doped SiO2 phosphor prepared by sol–gel process

SiO2 doped with Er3+ and Tm3+ rare earth ions was prepared by sol–gel process. Three band emission, blue (460 nm Tm), green (520 nm Er), red (665 nm Er, 705 nm Tm) and (NIR) near infra-red (875 nm Er or 865 nm Tm) from Tm or Er single doped SiO2 powder were measured. Simultaneous emission of Er and Tm ions was observed in the co-doped SiO2 powder samples. Red, green and blue (RGB) colours were measured from the SiO2:Er, Tm samples and the change in the intensities with change in accelerating voltage was also observed. A blue emission peak at 490 nm originating from 4F5/2 → 4I15/2 transition was observed at higher Er ions concentrations. The increase of the red, green, NIR and the decrease of the blue emission peak intensities with an increase in the accelerating beam voltage is reported. A mechanism for such behaviour is explained.