Clarifying the Different Roles of Rare Earth Ions in the Crystallization of Upconversion Oxyfluoride Glass Ceramics by Solid-State Nuclear Magnetic Resonance Spectroscopy

Abstract

Rare earth ion-doped oxyfluoride glasses in the system 50SiO 2 −(50 − x)PbO−xPbF 2 −mLa 2 O 3 −nEr 2 O 3 were prepared by the melt-quenching method. PbF 2 and LaF 3 were selectively crystallized by subsequent heat treatment in these glasses. The promotion and suppression effects of La 3+ ions on the crystallization of PbF 2 were observed in this selective crystallization. We used advanced solid-state nuclear magnetic resonance (NMR) and X-ray diffraction techniques to probe the structural evolution in the atomic level during these crystallizations. Based on the in-depth structure study, it can be inferred that both the different effects arise from the stronger ability of La 3+ ions in attracting F − ions than that of Pb 2+ ions. Intensive upconversion visible luminescence was observed in these glasses. The NMR and the upconversion luminescence results imply that most Er 3+ ions are dissolved in the LaF 3 crystal rather than in the PbF 2 crystal and the glass phases even when the content of the LaF 3 crystal is as small as less than 1 mol %. The results show that the past expectation that rare earth ions are homogenously incorporated into bivalent metal fluoride crystals might not be right and prove the validity of the strategy that multiple rare earth ions are codoped to increase the upconversion luminescent efficiency.

The effect of rare earth (RE3+) ionic radii on transparent lanthanide-tellurite glass-ceramics: correlation between ‘hole-formalism’ and crystallization

“…It is generally accepted that the composition of the crystallite nuclei is purely governed by the distribution of glass-former and modifying additives inside the glass network. Yu et al 54 has reported that distribution of RE 3+ ions in the glass matrix plays a crucial role during the ceramization of glass. In LGTT glass, it is assumed that La, Gd and doped trivalent RE ions are distributed homogeneously.…”

The Transformation from Translucent into Transparent Rare Earth Ions Doped Oxyfluoride Glass‐Ceramics with Enhanced Luminescence

“…F1 signal can be assigned to the F in the La–F‐Ba linkage. [ 33 ] Both F2 and F3 signals are related to F species involved in the F‐Al linkages of Al‐F‐Al and Na‐F‐Al, respectively. [ 34,35 ] Upon HT, the F1 resonance shifts from −12 to –18 ppm, indicating that some of the F ions participate in the formation of the Ba 2 LaF 7 crystals, rather than stay in the glass matrix.…”

Fluorophosphate Upconversion-Luminescent Glass-Ceramics Containing Ba2LaF7:Er3+ Nanocrystals: An Advanced Solid-State Nuclear Magnetic Resonance Study

“…In previous research, we only observed the competition between the cations to attract F − . In the glass with the composition 50SiO 2 −40PbO−10PbF 2 −1La 2 O 3 , 35 La 3+ demonstrated stronger ability than Pb 2+ to attract F − . Thus, the LaF 3 crystals were preferentially precipitated, while the precipitation of PbF 2 was suppressed by La 3+ .…”

“…Recently, we studied Er 3+ -doped 50SiO 2 –40PbO–10PbF 2 –1La 2 O 3 and 55SiO 2 –10Al 2 O 3 –10CaO–20CaF 2 –5La 2 O 3 glasses. We attempted to precipitate PbF 2 and CaF 2 crystals from these two glasses, respectively, after which rare-earth (Re) ions could be homogeneously incorporated into the crystals.…”