Structural and optical investigations of Eu~(3+) ions in lead containing alkali fluoroborate glasses

摘要

Lead containing alkali fluoroborate glasses (LAFB) with molar composition of 20PbO + 5CaO + 5Z-nO + 10AF + 59B_2O_3 + 1 Eu_2O_3 (where A = Li, Na and K) were prepared and investigated by the TG-DTA, FT-Raman, optical absorption, fluorescence and decay curve analysis. The influence of alkali content on the structure of borate glasses was investigated by FT-Raman spectroscopy. The thermal properties of the glasses have been studied by TG-DTA analysis. Judd-Ofelt intensity parameters are derived from the absorption spectra and also from the emission spectra under various constraints. The effect of ther-malization on the oscillator strengths of the absorption transitions originating from the ground (~7F_0) and the first excited (~7F_1) states of Eu~(3+) ions have been discussed. The J-O intensity parameters obtained by applying thermal correction to ~7F_0 → ~5D_2 and ~7F_6 absorption oscillator strengths were used to calculate the various spectroscopic properties. The predicted values of radiative lifetime (τ_R) and luminescence intensity branching ratio (β_R) are compared with the measured values for ~5D_0 level. The decay profiles were found to be single exponential in all the three glasses. The spectroscopic properties confirm the potentiality of present LAFB glasses doped with Eu~(3+) ions as laser host materials to produce an intense red luminescence at 612 nm corresponding to ~5D_0 →~7F_2 emission level and have significant importance in the development of emission rich optical systems.