Yellow to orange-reddish glass phosphors: Sm 3+ , Tb 3+ and Sm 3+ /Tb 3+ in zinc tellurite-germanate glasses

An optical spectroscopy analysis of TeO-GeO 2 -ZnO glass co-activating Sm 3+ /Tb 3+ ions was carried out through Raman, photoluminescence spectra and decay time profiles as a function of Sm 3+ concentration. According to the estimated CIE1931 chromaticity coordinates, the color of the emission can be adjusted from the yellow light region (0.4883, 0.4774), towards the reddish light region (0.5194,0.4144) by increasing the Sm 3+ content from 1, 3, 5% mol, co-doped with 1% mol Tb 3+ under co-excitation of Sm 3+ and Tb 3+ at 378 nm. The color temperatures are in the range of 1379–2804 K. Such photoluminescence is generated by the 4 G 5/2 → 4 H 5/2 , 4 H 7/2 , 4 H 9/2 emissions of Sm 3+ in addition to the 5 D 4 → 7 F 6,5,4,3 emissions of Tb 3+ ; the single doped Sm 3+ glass displayed an intense orange light. Meanwhile, co-doped Sm 3+ /Tb 3+ glasses excited at 378 nm showed a significant reduction in Tb 3+ emission, with a simultaneous increment in the reddish-orange emission of Sm 3+ , due to a non-radiative resonant energy transfer from Tb 3+ to Sm 3+ . Decay time profile analysis of the Tb 3+ emission as function of Sm 3+ ion content suggests that an electric dipole–dipole interaction into Tb 3+ –Sm 3+ clusters might dominate in the energy transfer process, with an efficiency and probability of 0.22, 0.27, 0.38 and 122.8, 327.6, 522.7 s −1 , respectively.