Radioluminescence and X-ray excited optical luminescence of SrAl2O4:Eu nanopowders

Nanopowders of SrAl2O4 and SrAl2O4:Eu3+ were prepared via a proteic sol–gel methodology. The prepared materials presented a single crystalline phase, confirmed by XRD measurements. AFM results indicate that the average particle size is about 53 nm. X-ray absorption spectra show the typical absorption associated with the L2 and L3 Sr and the L3 Eu edges. X-ray excited optical luminescence – XEOL emission showed the same spectra in both X-ray energy ranges around the L2/L3 Sr or the L3 Eu edges. The XEOL spectrum is composed of an intense peak around 515 nm followed by a weaker emission peaking at 624 nm. The first XEOL peak is due to the emission of Eu2+, while the second one is due to Eu3+ 4f–4f transitions. The irradiated samples exhibited a persistent radiation damage that changes the colour of the sample and also influenced the reduction in the scintillation efficiency.