Eu3+/Tb3+ codoped PbF2 nanocrystals in sol–gel glass–ceramic materials: Fabrication, structure and properties

Abstract

In this work, the transparent glass-ceramics with PbF2 nanocrystals doubly-doped with Eu3+ and Tb3+ ions were obtained by low-temperature sol–gel method. Thermal and structural properties were examined using thermogravimetric analysis (TG), differential scanning calorimetry (DSC) as well as IR-ATR spectroscopy. The formation of β-PbF2 nanocrystals was confirmed by XRD results. The optical properties were studied based on excitation and emission spectra and luminescence decay analysis. Upon direct excitation of Eu3+ ions at 393 nm, only the characteristic transitions from the 5D0 state of Eu3 were observed, but upon excitation of Tb3+ ions at 351 nm the characteristic transitions of Tb3+ and Eu3+ were registered, and emission of Eu3+ is impressively long-lived (7.43 ms) in comparison to that one obtained under 393 nm excitation. It proofs that energy transfer Tb3+ → Eu3+ occurs. Obtained luminescence spectra and double-exponential character of lifetimes indicated the successful migration of dopants into low phonon energy PbF2 nanocrystal phase.