Synthesis and Structural Probing of Eu³⁺ Doped BaYF₅ Nano‐Crystals in Transparent Oxyfluoride Glass‐Ceramics

Abstract

Transparent oxyfluoride glass‐ceramics containing Eu: BaYF5 nano‐crystals in the newly developed SiO2–K2CO3–BaF2–YF3–Sb2O3 glass system are synthesized by melt quenching method followed by optimized ceramization process. The X‐ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy confirmed the precipitation of tetragonal BaYF5 nano‐crystals in glass matrix. The coexistence of Eu2+ and Eu3+ ions in both glass and glass‐ceramics are ascertained from their emission and excitation spectra. The in situ formation of divalent europium (Eu2+) along with Eu3+ during high temperature synthesis under ambient atmosphere is explained through optical basicity model. The Eu3+ emission from upper excitation states (5D3−1) and reduced asymmetry ratio (R = IED/IMD) in glass‐ceramics have established the dopant ion incorporation into fluoride nano‐crystalline environment. The observed luminescence properties of Eu:BaYF5 are compared with that of Eu:BaYF5 nanocrystals containing transparent glass‐ceramics and their marked differences are discussed.

Transparent oxyfluoride glass ceramics

“…x Y x F 2+x solid solution with different lattice parameters as formation of Ba 4 Y 3 F 17 (compound of this formula is real, it actually crystallizes in slightly trigonaldistorted fluorite system) or phantom-phase "BaYF 5 " [196], and assigned peculiar Miller indexes to the diffraction peaks in very simple X-ray diffraction patterns in both cases. Polyshchuk et al [308] grounlessly interpreted the fluorite phase obtained by the thermal treatment of MnNbOF 5 -BaF 2 -BiF 3 glass as Ba 0.55 Bi 0.45 F 2.45 , despite the fact that their X-ray diffraction pattern did not have any traces of crystal lattice distortion or ordering.…”

Controllable synthesis of glass ceramics containing YF3:Eu3+ nanocrystals: Well‐preserved Eu and prolonged lifetime

“…That is to say, when Eu 3+ ions locate in a site with inversion symmetry, the 5 D 0 → 7 F 1 transition is dominating, while in a site without inversion symmetry the 5 D 0 → 7 F 2 transition is stronger. Therefore, the R/O value (PL intensity ratio of 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 ), known as asymmetry ratio, has been proposed as a judgment indicator of structural symmetry . The calculated R/O values presented in Table are 0.78, 0.56, and 0.49 for 3 wt%to 5 wt% GC composites, respectively, which are significantly smaller than those in previous work with similar GC system by conventional methods.…”

Stabilization of divalent Eu2+ in fluorosilicate glass-ceramics via lattice site substitution

“…17,18 As strategies (i) and (ii) accompany drawbacks such as introducing impurities into the system or leading to infeasibility for elaborated optimization of concentration and distribution of Eu 2+ , strategies (iii) and (iv) are usually considered to be more executable. Using strategy (iv), silicate, 19,20 aluminosilicate, 10,15,21 borophosphate 22,23 and uoride crystalline phases [24][25][26] have been reported as good stabilizers for divalent Eu 2+ . Among them, uoride crystalline phases show most advantages owing to their ultrasmall sizes down to several nanometers, similar refractive indices with silicate glasses, ideal host to selectively enrich Eu 2+ .…”