Concentration Dependent Luminescence and Energy Transfer Properties of Samarium Doped LLSZFB Glasses

Recently, great importance has been devoted to borate glass systems doped with rare-earth ions because of their unique peculiar properties in the field of photonics for optical applications. The purpose of the present study is to investigate the effect of concentration of Sm3+ ions on the luminescence properties of lead fluoroborate glasses through the energy transfer mechanism. Samarium doped lead fluoroborate glasses with chemical composition 20PbF2 .10Li2O .5SrO .5ZnO. (60-x) B2O3. xSm2O3 (where x = 0.1, 0.5, 1.0, 1.5 and 2.0 mol %) were prepared by means of melt quenching method. The concentration dependent luminescence properties were investigated in detail from the optical absorption, photoluminescence and decay analysis. Judd-Ofelt (J-O) theory was applied to analyze the optical absorption spectra. The experimental oscillator strengths of absorption bands have been used to determine the J-O parameters. Using the J-O parameters Ωλ (λ = 2, 4 and 6) and luminescence data several radiative parameters were obtained. From the luminescence spectra, it was noticed that luminescence quenching starts at higher concentrations of Sm3+ ions (x ≥ 0.5 mol %). The decay curves of 4G5/2 → 6H7/2 transition exhibit a single exponential at lower dopant concentrations (x= 0.1 and 0.5 mol %) and non-exponential at higher concentrations (x ≥ 1 mol %). The concentration quenching was attributed to the energy transfer through the cross-relaxation between Sm3+ ions. The non-exponential curves were well fitted to Inokuti-Hirayama model for S = 6, indicating that the energy transfer between Sm3+ - Sm3+ ions is of dipole-dipole type. The calculated color coordinates of the as-prepared glasses fall within the reddish-orange region of the CIE diagram. All the experimental results indicate that the 0.5 mol% Sm3+ ions doped LLSZFB glass can be a possible choice for solid state lighting and display applications.