Energy transfer investigation of Sm3+/Eu3+ CaBAl glasses

Sm3+/Eu3+ codoped CaBAl glasses were prepared by conventional melt-quenching method, and their structural and optical properties were studied. The values of volumetric density and electronic polarizability showed an increase with the addition of Sm2O3. The Fourier-transform infrared spectroscopy (FTIR) spectra indicated the existence of trigonal and tetrahedral borate groups. The N-4 values revealed that Sm2O3/Eu2O3 codoping favored the conversion of structural units from BO4 to BO3. The observed absorption bands in UV/VIS spectra were attributed to Eu3+ and Sm3+ transitions, from the ground states F-7(0) and H-6(5/2) to the various excited states. Color coordinates at CIE diagram were studied for the codoped glasses upon exciting at 405 nm. The energy transfer from the level (4)G(5/2) of Sm3+ to the D-5(0) level of Eu3+ was verified by means of the luminescence results. With the addition of Sm3+, emission intensity of Eu3+ has been enhanced due to migration of Sm3+ excitation energy. The mechanism for energy transfer from Sm3+ to Eu3+ was investigated by Dexter energy transfer formula and Reisfeld's theory application on photoluminescence decay curves. A decrease in the lifetime of (4)G(5/2) -> H-6(7/2) transition was observed when Sm3+ was increased, probably due to ion-ion interaction and excitation energy migration.