resumo
A multicomponent aluminoborosilicate photoluminescent glass was synthesized by introducing Pb(II) and NaBr in its composition. The room-temperature photoluminescence is due to the existence of 4 nm nanocrystals, shown using TEM imaging and XRD analysis, which are assigned to PbBr2 nanocrystals. The glasses display a broad emission band with a peak at 2.85 eV by exciting at 3.35 eV, with an anisotropy equal to 0.19 at room temperature. At 77 K, the emission intensity increases 1 order of magnitude and a vibronic structure appears, indicating an electron-phonon coupling with the glass matrix. Time-resolved luminescence measurements of these nanocrystals reveal mixed-order kinetics, with second-order recombination of self-trapped electron centers and a first-order temperature-dependent nonradiative rate constant connected with pathways due to confinement of self-trapped centers.
palavras-chave
HALIDE PHOTOCHROMIC-GLASSES; SILICATE-GLASSES; ELECTRON-TRANSFER; BORATE GLASSES; RAMAN; LUMINESCENCE; MELTS; MECHANISM; SPECTROSCOPY; CRYSTALS
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Ruivo, A; Andrade, SM; Rocha, J; Laia, CAT; Pina, F
nossos autores
João Rocha
Prof. Catedráticoagradecimentos
This work has been supported by the European project NMP4-SL-2012-310651 under FP7-NMP-2012-SMALL-6 and by Fundacao para a Ciencia e a Tecnologia through grants PEstC/EQB/LA0006/2013 and PEst-C/CTM/LA0011/2011. The authors would like to thank the Fundacao para a Ciencia e Tecnologia (FCT) for financial support under contracts PTDC/EAT/67354/2006 and PTDC/EAT-AVP/118520/2010. A.R. would like to thank FCT (SFRH/BD/46659/2008) for a grant.