Sol-Gel Glass-Ceramic Materials Containing CaF2:Eu3+ Fluoride Nanocrystals for Reddish-Orange Photoluminescence Applications

Abstract

CaF 2 :Eu 3+ glass-ceramic sol-gel materials have been examined for reddish-orange photoluminescence applications. The transformation from precursor xerogels to glass-ceramic materials with dispersed fluoride nanocrystals was verified using several experimental methods: differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR-ATR), energy dispersive X-ray spectroscopy (EDS) and photoluminescence measurements. Based on luminescence spectra and their decays, the optical behavior of Eu 3+ ions in fabricated glass-ceramics were characterized and compared to those of precursor xerogels. In particular, the determined luminescence lifetime of the 5 D 0 excited state of Eu 3+ ions in nanocrystalline CaF 2 :Eu 3+ glass-ceramic materials is significantly prolonged in comparison with prepared xerogels. The integrated intensities of emission bands associated to the 5 D 0 → 7 F 2 electric-dipole transition (ED) and the 5 D 0 → 7 F 1 magnetic-dipole transition (MD) are changed drastically during controlled ceramization process of xerogels. This implies the efficient migration of Eu 3+ ions from amorphous silicate sol-gel network into low-phonon energy CaF 2 nanocrystals.

Structural and Photoluminescence Investigations of Tb3+/Eu3+ Co-Doped Silicate Sol-Gel Glass-Ceramics Containing CaF2 Nanocrystals

“…It was clearly visible that the intensities of bands A, B, and E decreased during the transformation of xerogels into glass-ceramics. Indeed, since Ca(CF 3 COO) 2 underwent thermal decomposition during controlled ceramization [ 41 ], the vibrations from the C–F bond disappeared for glass-ceramics, and bands A and B should have originated only from vibrations inside the Si–O–Si siloxane bridges. Further, a decrease in the intensity of band E clearly pointed to the conversion of Q 2 structural units into Q n (n = 3, 4) units as a consequence of polycondensation reaction.…”

“…Therefore, such materials could be successfully predisposed for use in laser technologies [ 38 ], bio-imaging [ 39 ], or to increase the efficiency of solar cells [ 40 ]. Moreover, according to our previous results for sol-gel nano-glass-ceramics containing divalent metals fluorides, MF 2 (M = Ca, Sr, Ba), singly-doped with Eu 3+ ions, the most efficient segregation of Eu 3+ inside fluoride crystal lattice, was reported for the SiO 2 -CaF 2 system [ 41 , 42 , 43 ]. Indeed, a clear correlation was observed between the average decay time of the 5 D 0 state and growing difference in ionic radius of Eu 3+ and each of individual M 2+ cation in the following order: Ca 2+ → Sr 2+ → Ba 2+ (SiO 2 -CaF 2 :Eu 3+ : τ avg = 11.92; SiO 2 -SrF 2 :Eu 3+ : τ avg = 7.77; SiO 2 -BaF 2 :Eu 3+ : τ avg = 4.08 ms).…”

“…The series of xerogels co-doped with Tb 3+ and Eu 3+ ions were synthesized using the sol-gel method described elsewhere [ 41 , 46 ]. All reagents were taken from Sigma Aldrich Chemical Company (St. Louis, MO, USA).…”

Determination of the Refractive Index of Particles Through the Immersion Solid Matching Method

“…The method was tested using calcium fluoride (CaF 2 ) particles as a sample. CaF 2 finds a wide variety of applications in metallurgical, chemical, and optical materials industries [11]. Therefore, raw material quality is an essential part of process control.…”

Rare earth ion (RE = Tb/Eu/Dy) doped nanocrystalline oxyfluoride glass‐ceramic 5BaF2–95SiO2

“…[15][16][17][18] Pawlik et al reported the fluorescence characteristics of Eu 3+ doped GCs containing CaF 2 / SrF 2 nanocrystals. 19,20 In 2006, the transparent SiO 2 -BaF 2 GCs doped with different content of Er 3+ were prepared by the sol-gel method by Daqin Chen. 21 As known, Ca, Sr, and Ba are in the same main group.…”