Photoluminescence and energy transfer in transparent glass-ceramics based on GdF3:RE3+ (RE = Tb, Eu) nanocrystals

Abstract

Abstract In present work, the transparent oxyfluoride glass-ceramic samples containingGdF 3 :RE 3+ (RE = Tb, Eu) nanocrystals (nGCs) were fabricated via controlled heat-treatment of precursor xerogels prepared using a sol-gel method. The formation of GdF 3 nanocrystalline phase from gadolinium(III) trifluoroacetate was verified based on XRD measurements. The average crystal sizes calculated from Scherrer formula were estimated to ∼10 nm as well as ∼6 nm for Tb 3+ - and Eu 3+ -doped samples, respectively. The optical behavior of prepared sol-gel samples was evaluated based on photoluminescence excitation (PLE) and emission spectra (PL) as well as luminescence decay analysis. Obtained samples exhibit the 5 D 4 → 7 F J ( J = 6–3, Tb 3+ ) and the 5 D 0 → 7 F J ( J = 0–4, Eu 3+ ) emission bands recorded within the visible spectral area under excitation at near-UV (393 nm (Eu 3+ ), 351, 369, 378 nm (Tb 3+ )) as well as middle-UV illumination (273 nm (Gd 3+ )). Additionally, based on recorded decay curves, the luminescence lifetimes ( τ m ) for the 5 D 4 (Tb 3+ ) and the 5 D 0 (Eu 3+ ) excited states were also evaluated. In general, recorded luminescence spectra and double-exponential character of decay curves for nGCs indicated a successful migration of Tb 3+ and Eu 3+ dopantions from amorphous silicate framework to low-phonon energy GdF 3 nanocrystal phase.