Transparent SiO2-GdF3 sol–gel nano-glass ceramics for optical applications
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Transparent oxyfluoride nano-glass-ceramics (GCs) containing GdF3 nanocrystals undoped and doped with 0.5 Eu3+ (mol%) were obtained by a novel sol–gel method after sintering at temperatures such low as 550 °C. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) show the precipitation of GdF3 nanocrystals with size between 7 and 10 nm, depending on the crystalline phase (hexagonal or orthorhombic) and the heating time. Fourier transform infrared spectroscopy (FTIR) analysis allows following the system evolution during the heat treatment showing the decomposition of trifluoroacetic acid (TFA), used as fluorine precursor, together with the formation of fluoride lattice bonding. Energy dispersive X-ray (EDX) analysis confirms the incorporation of the RE ions in the fluoride nanocrystals in the GCs. The ions incorporation on the GdF3 crystals is also supported by optical characterisation. Photoluminescence measurements result in a well resolved structure together with a narrowing of the Eu3+ emission and excitation spectra in the GCs compared to the xerogel. Moreover, the asymmetry ratio between the electric dipole transition (5D0→7F2) to the magnetic dipole transition (5D0→7F1) is reduced in GCs, indicating that Eu3+ ions are incorporated in the GdF3 crystalline phases. Moreover, Gd3+→Eu3+ energy transfer with enhancement of the energy transfer efficiency was observed in the GCs, further supported by fluorescence decay curves.
Eu3+ doped SiO2-GdF3 GCs with 20 mol% of crystalline phase has been successfully obtained by sol–gel method.
The use of methyl triethoxysilane allows obtaining crack-free GCs samples and reduces the hydroxyl groups.
Energy transfer with enhancement of efficiency was observed from Gd3+ to Eu3+ in the nanocrystals.
KeywordsSol–gel GdF3 Oxyfluoride nano-glass-ceramic Luminescence Energy transfer
This work was supported by MINECO under Projects N° MAT2013-48246-C2-1-P, MAT2013-48246-C2-2-P and Basque Country University PPG17/07 and GIU17/014. The authors thank the access to the Spanish Beamline (SpLine) at the ESRF facilities in Grenoble. J.J. Velázquez also acknowledges MINECO under Grant FPDI-2013-16895. This paper is also a part of dissemination activities of project FunGlass. This project has received funding from the European Union´s Horizon 2020 research and innovation programme under grant agreement No 739566.
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Conflict of interest
The authors declare that they have no conflict of interest.
- 8.De Pablos-Martin A, Ferrari M, Pascual MJ, Righini GC (2015) Glass-ceramics: a class of nanostructured materials for photonics. Riv del Nuovo Cim. https://doi.org/10.1393/ncr/i2015-10114-0
- 11.Velázquez JJ, Yanes AC, Del-Castillo J, et al. (2010) Spectroscopic characterization and up-conversion in sol-gel derived Yb3+-Pr3+ co-doped SiO2-LaF3 nano-glass-ceramics. J Non Cryst Solids. https://doi.org/10.1016/j.jnoncrysol.2010.03.001
- 12.Yanes AC, Velázquez JJ, Del-Castillo J, et al. (2008) Site-selective spectroscopy in Sm3+-doped sol–gel-derived nano-glass-ceramics containing SnO2 quantum dots. Nanotechnology. https://doi.org/10.1088/0957-4484/19/29/295707
- 13.Fujihara S, Tada M, Kimura T (1998) Sol–gel processing of LaF3 thin films. Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/J Ceram Soc Jpn 106:124–126Google Scholar
- 33.Cullity BD (1978) Elements of X-ray diffraction, 2nd edition. Addison-Wesley Publ Co, Reading, MA 100-105-279. https://doi.org/10.1119/1.1934486
- 34.Gorni G, Pascual MJ, Caballero A, et al. (2018) Crystallization mechanism in sol-gel oxyfluoride glass-ceramics. J Non Cryst Solids. https://doi.org/10.1016/j.jnoncrysol.2018.01.031
- 35.Gorni G, Velázquez JJ, Mosa J, et al. (2018) Transparent glass-ceramics produced by sol-gel: a suitable alternative for photonic materials. Materials. https://doi.org/10.3390/ma11020212