Investigation of spectroscopic properties of Sm-Eu codoped phosphate glasses

Phosphate glasses with chemical compositions of 74.5NaH2PO4-20ZnO-5Li2O-0.5Sm2O3 and 74NaH2PO4-20ZnO-5Li2O-0.5Sm2O3-0.5Eu2O3 were synthetized by melt quenching method. We investigated the influence of Sm3+/Eu3+ doping on the optical properties of phosphate glasses. X-ray Diffraction indicates that the samples have an amorphous structure. DSC measurements show a good thermal stability of phosphate glasses. Using the absorption spectra, Judd-Ofelt analysis was applied to absorption bands of Sm3+ (4f5) to carry out the three phenomenological parameters of Judd-Ofelt (JO). According to the obtained values of Ω2, Ω4 and Ω6, some radiative properties were theoretically determined. We report both the photoluminescence (PL) and the PL lifetime measurements of a prominent emission transition 4G5/2 → 6H5/2 (604 nm) of Sm3+ both in absence and in presence of Eu3+. It is shown that Eu3+ ions act as sensitizers for Sm3+ ions and contribute largely to the improvement of the radiative properties of phosphate glasses. An improvement of the PL lifetime value after adding Eu3+ ions (4.58 ms) is reported. The predicted lifetime (τrad) calculated by Judd-Ofelt theory and the experimental lifetime (τmeas) for the prepared phosphate glasses were compared with those of other works. Photoluminescence (PL) intensity of 4G5/2 → 6H5/2 (604 nm), 4G5/2 → 6H7/2 (567 nm), 4G5/2 → 6H9/2 (650 nm) and 4G5/2 → 6H11/2 (706 nm) and the quantum efficiency (η) for the excited 4G5/2 level were enhanced after adding Eu3+. The radiative properties obtained for (Sm, Eu) codoped phosphate glasses suggest that the present material can be a potential candidate for the development of color display devices.