As can be seen in Fig. 3 which depicts the conventionalemission spectra, all the glasses exhibit emission bands locatedbetween 575 and 650 nm, as well. This indicates that some Eu2+ions are oxidized to Eu3+during the preparation of the glasses.The spectra exhibit also 2 bands in the 350–575 nm range, theintensity of which seems to depend on the glass matrix and onthe MPs concentration. However, as for the persistent lumines-cence spectra, it is not possible to compare the intensity of theemission. The bands in the 350–575 nm range can be related tothe luminescence of Eu2+located in two different cation sitesFig in the Sr4Al14O25structure.