a b s t r a c tIn this work, Eu 3 + -doped lead borosilicate glasses (SiO 2 -B 2 O 3 -PbO 2 ) synthesized by fusion method had their optical properties investigated as a function of temperature. Atomic Force Microscopy images obtained for a glass matrix annealed at 350 and 500 1C show a precipitated crystalline phase with sizes 11 and 21 nm, respectively. Besides, as the temperature increases from 350 to 300 K a strong Eu 3 + photoluminescence (PL) enhancement takes place. This anomalous feature is attributed to the thermally activated carrier transfer process from nanocrystals and charged intrinsic defects states to Eu 3 + energy levels. In addition, the PL peaks in this temperature range were assigned to the Eu 3 + transitions 5 D 0 -7 F 2 , at 612 nm, 5 D 0 -7 F 1 , at 595 nm, and 5 D 0 -7 F 0 , at 585 nm. It was also observed that the 5 D 0 -7 F 3 and 5 D 0 -7 F 4 PL bands at 655 and 700 nm, respectively, show a continuous decrease in intensity as the temperature increases.