Speciation of ‘Eu’ in sol–gel derived alkali barium borosilicate glass: Time resolved photoluminescence (TRPL) and Judd—Ofelt analysis

Time resolved photoluminescence spectroscopic (TRPLS) technique was used to investigate the speciation of Eu ion in alkali barium borosilicate glasses prepared via sol–gel method. The metal ion concentration and the annealing temperature were optimized for best signal intensity. It was observed that the presence ofOH groups in the samples reduced the luminescence decay time values. Upon heating the system at higher temperature, the number ofOH groups reduced and the lifetime as well as the intensity increased. At elevated temperatures, it was found that Eu was stabilized in two different asymmetric environments having large site distribution. The overall symmetry around the two metal ion sites was estimated to be C2. Judd—Ofelt intensity parameters for the metal ion were evaluated in all the samples adopting standard procedure. It was observed that, for all the samples, Ω2 > Ω4. This indicated the existence of a fair degree of covalency in the metal and ligand bonding.