Structural and luminescence properties of silica powders and transparent glass-ceramics containing LaF3:Eu3+ nanocrystals

Abstract

In this work, silica powders and transparent glass-ceramic materials containing LaF3:Eu3+ nanocrystals were synthesized using the low-temperature sol-gel technique. Prepared samples were characterized by TG/DSC analysis as well as X-ray diffraction and IR spectroscopy. The transformation from liquid sols toward bulk powders and xerogels was also examined and analyzed. The optical behavior of prepared Eu3+-doped sol-gel samples were evaluated based on photoluminescence excitation (PLE: λem = 611 nm) and emission (PL: λexc = 393 nm, λexc = 397 nm) spectra as well as luminescence decay analysis. The series of luminescence lines located within reddish-orange spectral scope were registered and identified as the intra-configurational 4f6-4f6 transitions originated from Eu3+ optically active ions (5D0 → 7FJ, J = 0-4). Moreover, the R/O-ratio was also calculated to estimate the symmetry in local framework around Eu3+ ions. The luminescence spectra and double-exponential character of decay curves recorded for fabricated nanocrystalline sol-gel samples (τ1(5D0) = 2.07 ms, τ2(5D0) = 8.07 ms and τ1(5D0) = 0.79 ms, τ2(5D0) = 9.76 ms for powders and glass-ceramics, respectively) indicated the successful migration of optically active Eu3+ ions from amorphous silica framework to low phonon energy LaF3 nanocrystal phase.