Research Information System
JOURNAL OF LUMINESCENCE, vol.192, pp.263-268, 2017 (SCI-Expanded)
In order to elucidate the effect of europium content on the optical and luminescent properties of borogermanate glasses, a series of Eu3+ doped 30B(2)O(3)-40GeO(2)-(30-x)Gd2O3 glasses with various doping levels (x = 1-9 mol%) have been synthesized and studied with transmission, absorption, photoluminescence and decay time measurements. The transmission spectra proved that the title glasses maintained a high transparency about 80% in the 440 to 900 nm region. Based on the absorption spectra, the optical band gaps obtained from Tauc's plot can be narrowed by increasing content of Eu3+. From the photoluminescence spectra, the strongest red emission has been observed from the D-5(0)-> F-7(2) level of Eu3+ ions in borogermanate glasses. The strongest emission and excitation intensities of Eu3+ ions are at the doping level of x = 7 mol% and then these intensities decrease due to concentration quenching. The red to orange ratio (R/O) of D-5(0)-> F-7(2) to D-5(0)-> F-7(1) transitions has been investigated to predict the local environment of Eu3+ ions. Judd-Ofelt (J-O) analyses have been performed from the emission spectra. The values of R/O and Omega(2) present an increase with increasing doping level, indicating the lower symmetric environment for Eu3+ ions and higher covalency for Eu-O bond. The emission efficiency calculated from J-O theory is 75% at x = 2 mol%. The decay time curves of R-6(7/2)-> S-8(7/2) transition of Gd3+ ions and D-5(0)-> F-7(2) transition of Eu3+ ions confirm the energy transfer from Gd3+ to Eu3+ ions.