Luminescence of CsGd2F7 : Er3+, Dy3+ under VUV excitation

Luminescence spectra from the deep UV to the visible as well as excitation spectra in the VUV/UV range have been studied for CsGd2F7 : Dy3+, CsGd2F7 : Er3+ and CsGd2F7 : Er3+, Dy3+. It has been found that under VUV excitation the latter crystal shows luminescence originating almost completely from Dy3+. The measured excitation spectra of the different emissions from CsGd2F7 : Er3+,Dy3+ gave evidence that in this crystal the energy transfer exists from Gd3+ to Er3+ and Dy3+ as well as from Er3+ to Gd3+ and Dy3+. Thus, by varying the concentration of the doping ions one can expect that for an optimal composition of this compound the down-conversion mechanism can result in a quantum efficiency of visible luminescence under VUV excitation higher than 100%.