Mechanisms of radioluminescence of rare earths doped SrAl2O4 and Ca12Al14O33 excited by X-ray

Pure and rare earth doped SrAl2O4 and Ca12Al14O33 have been synthesized by a new sol-gel proteic methodology. Photoluminescence (PL) and radioluminescence (RL) spectra show different behavior when excited with either UV light or X-ray radiation. Such behavior may be connected to the X-ray absorption/reduction of Eu ions process in samples. X-ray absorption spectroscopy (XAS) was carried out simultaneously with X-ray excited optical luminescence (XEOL) and the analysis indicates that are depends on the energy of excitation and the kind of excited species. Dispersive X-ray absorption spectroscopy (DXAS) was carried out to follow the kinetic of reduction process in the samples during the irradiation. The reduction process does not produce stable Eu2+ species. An overall analysis of the results makes possible to build the mechanisms of radioluminescence of rare earths doped SrAl2O4 and Ca12Al14O33 systems.