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.
The energy-transfer process and the related migration mechanism of excitation energy, important in the optical dynamics of Nd-doped glasses, were investigated. In order to study the migration mechanism and transfer process, Nd3+-doped oxide glasses were produced with doping concentration (N) ranging from 0.1to1.9wt% as Nd2O3. A microluminescence technique was used to measure the spatial distribution of the emitting light as a function of the distance from the center of the laser-excitation spot with different Nd3+-ion concentrations. Efficient long-range migration of excitation energy of Nd3+ ions was observed at 1.1wt% of Nd2O3. The critical distance between Nd3+ ions, estimated from the observed migration length, shows that dipole-dipole interaction is not the dominant mechanism for energy transfer. The mean free path for migratory excitation energy in the investigated material, assisted by absorption and scattering by defects or phonons, is the most probable mechanism for energy transfer.
Experimental evidence has been observed for energy transfer from CdS nanocrystals, synthesized by the fusion method, to Nd(3+) ions embedded in vitreous substrates. These dot samples doped with neodymium have been investigated by combined optical absorption (OA), photoluminescence (PL), and time-resolved photoluminescence (PLRT) techniques. Radiative and nonradiative energy transfers between CdS dot and Nd(3+) ion levels, to our knowledge not reported before, can be clearly observed in the PL spectra where the emission band valleys correspond exactly to the energy absorption peaks of the doping ion. The PLRT data reinforce these energy transfer mechanisms in which the increasing overlap between the CdS PL band and the OA to the Nd(3+) levels decreases stimulated emissions from the doping ions.
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