Optical absorption and photoluminescence characteristics of Sm3+ ions in lead silicate glasses mixed with different concentrations of Al2O3 (5-10 mol%) have been investigated. From these studies, the radiative properties viz., spontaneous emission probability A, the total emission probability, the radiative lifetime tau(R), the fluorescent branching ratio beta of emission transition of (4)G(5/2) -> H-6(7/2) along with other transitions for Sm3+ have been evaluated and found to be the highest for the glass mixed with 8.0 mol% of Al2O3. The IR spectral studies have indicated that Al3+ ions do participate in the glass network with AlO4 and AlO6 structural units and further revealed that the concentration of octahedral aluminium ions induce bonding defects in the glass network. Such bonding defects are assumed to be responsible for low phonon losses in these glasses and lead to higher values of radiative parameters for the glass mixed with 8.0 mol% of Al2O3. (C) 2011 Elsevier Ltd. All rights reserved.