“…48 The most intense PL intensity is obtained at 20 mol%, indicating that the distance between neighbor Eu 3+ ions reached its critical distance threshold, R c . 8,11,48 In this case, the R c value of 7.02 Å can be determined using the Blasse equation, which is higher than the critical value of 5 Å for exchanging energy by interaction, implying the governance of the multipolar interaction for the quenching mechanism. 8,16 It is well known that multipolar interaction oen contains three types that correspond to the value of the characteristic function for multipolar interaction types: dipole-dipole, dipole-quadrupole, and quadrupolequadrupole interactions.…”