Transparent SiO2-GdF3 sol–gel nano-glass ceramics for optical applications

Velázquez, J. J.; Mosa, Jadra; Gorni, Giulio; Balda, Rolindes; Fernández, José Rodríguez; Pascual, L.; Durán, Alicia; Castro, Yolanda

doi:10.1007/s10971-018-4693-z

Cited by 30 publications

(22 citation statements)

References 40 publications

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“…The same sample measured in an argon atmosphere showed similar characteristics; therefore, the exothermic peak is associated with NaGdF 4 crystallization. Similar features are obtained for SiO 2 -GdF 3 composition and described elsewhere [112]. …”

Section: Resultssupporting

confidence: 84%

Transparent Glass-Ceramics Produced by Sol-Gel: A Suitable Alternative for Photonic Materials

et al. 2018

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Transparent glass-ceramics have shown interesting optical properties for several photonic applications. In particular, compositions based on oxide glass matrices with fluoride crystals embedded inside, known as oxyfluoride glass-ceramics, have gained increasing interest in the last few decades. Melt-quenching is still the most used method to prepare these materials but sol-gel has been indicated as a suitable alternative. Many papers have been published since the end of the 1990s, when these materials were prepared by sol-gel for the first time, thus a review of the achievements obtained so far is necessary. In the first part of this paper, a review of transparent sol-gel glass-ceramics is made focusing mainly on oxyfluoride compositions. Many interesting optical results have been obtained but very little innovation of synthesis and processing is found with respect to pioneering papers published 20 years ago. In the second part we describe the improvements in synthesis and processing obtained by the authors during the last five years. The main achievements are the preparation of oxyfluoride glass-ceramics with a much higher fluoride crystal fraction, at least double that reported up to now, and the first synthesis of NaGdF4 glass-ceramics. Moreover, a new SiO2 precursor was introduced in the synthesis, allowing for a reduction in the treatment temperature and favoring hydroxyl group removal. Interesting optical properties demonstrated the incorporation of dopant ions in the fluoride crystals, thus obtaining crystal-like spectra along with higher efficiencies with respect to xerogels, and hence demonstrating that these materials are a suitable alternative for photonic applications.

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Section: Resultssupporting

confidence: 84%

Transparent Glass-Ceramics Produced by Sol-Gel: A Suitable Alternative for Photonic Materials

et al. 2018

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“…During the heat treatment, decomposition promotes the precipitation of LaF 3 crystals in which Er 3+ ions become trapped. Other techniques, such as Energy Dispersive X-Ray Spectroscopy (EDXS), demonstrated an Eu enrichment in GdF 3 NCs after just 1 min of treatment at 550 °C [50], further supporting the aforementioned conclusions.…”

Section: Resultsmentioning

confidence: 61%

“…The difference of the crystal size with respect to the TEOS sample treated at 650 °C is associated with the higher heating rate (10 °C/min) used to crystallize the samples prepared with TEOS-MTES. The crystallization mechanism of similar GCs was extensively studied in previous papers [44,50], demonstrating how the decomposition reaction of lanthanide fluoroacetates leads to precipitation of NCs once the crystallization temperature is reached. The crystallization mechanism of these materials is, therefore, completely different from that of oxyfluoride glasses by MQ in which the crystal growth is a diffusion-controlled process.…”

Section: Resultsmentioning

confidence: 99%

Transparent Sol-Gel Oxyfluoride Glass-Ceramics with High Crystalline Fraction and Study of RE Incorporation

et al. 2019

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Transparent oxyfluoride glass-ceramic films and self-supported layers with composition 80SiO2-20LaF3 doped with Er3+ have been successfully synthesized by sol-gel process for the first time. Crack-free films and self-supported layer with a maximum thickness up to 1.4 µm were obtained after heat treatment at the low temperature of 550 °C for 1 min, resulting in a LaF3 crystal fraction of 18 wt%, as confirmed by quantitative Rietveld refinement. This is the highest value reported up to now for transparent oxyfluoride glass-ceramics prepared by sol-gel. This work provides a new synthesis strategy and opens the way to a wide range of potential applications of oxyfluoride glass-ceramics. The characterization by a wide range of techniques revealed the homogeneous precipitation of LaF3 nanocrystals into the glass matrix. X-ray absorption spectroscopy and electron paramagnetic resonance confirmed that the Er3+ ions are preferentially embedded in the low phonon-energy LaF3 nanocrystals. Moreover, photoluminescence (PL) measurements confirmed the incorporation of dopants in the LaF3 nanocrystals. The effective concentration of rare-earth ions in the LaF3 nanocrystals is also estimated by X-ray absorption spectroscopy.

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“…Dopant Eu 3+ ion incorporated successfully in the crystals, and XRD peaks of the hexagonal and orthorhombic phases of GdF 3 were shifted to larger 2θ angles. By careful observation of luminescence data, efficient energy transfer from Gd 3+ to Eu 3+ in the nanocrystals was noticed, as well as an increase in the Eu 3+ reddish visible emission [77]. Different composition of doped 90SiO 2 -10NaGdF 4 GCs was also investigated with a similar approach.…”

Section: Oxyfluoridegcsmentioning

confidence: 99%

“…For the last ten years, the GlaSS group at Ceramics and Glass Institute (CSIC) focused attention on the preparation of transparent glass-ceramics with low-phonon fluoride crystals, such as LaF 3 , NaGdF 4 , NaLuF 4 , KLaF 4 , etc., with rare-earth ions as dopants for optical applications [29,30,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78]. The main emphasis was on maximizing the crystalline fraction, maximum incorporation of the RE dopant, and further enhancement in luminescence profile.…”

Section: Oxyfluoridegcsmentioning

confidence: 99%

Glass-Ceramics Processed by Spark Plasma Sintering (SPS) for Optical Applications

et al. 2020

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This paper presents a review on the preparation of glass-ceramics (GCs) and, in particular, transparent GCs by the advanced processing technique of spark plasma sintering (SPS). SPS is an important approach to obtain from simple to complex nanostructured transparent GCs, full densification in a short time, and highly homogeneous materials for optical applications. The influence of the different processing parameters, such as temperature, pressure, sintering dwell time on the shrinkage rate, and final densification and transparency, are discussed and how this affects the glass material properties. Normally, transparent glass-ceramics are obtained by conventional melt-quenching, followed by thermal treatment. Additionally, the GC scan is produced by sintering and crystallization from glass powders. Hot pressing techniques (HP) in which the source of heating is high-frequency induction can be also applied to enhance this process. In the case of transparent ceramics and glass-ceramics, spark plasma sintering is a promising processing tool. It is possible to enhance the material properties in terms of its compactness, porosities, crystallization, keeping the size of the crystals in the nanometric scale. Moreover, the introduction of a high concentration of active gain media into the host matrix provides functional glass-ceramics systems with enhanced luminescence intensity through reducing non-radiative transitions like multi phonon relaxation (MPR) and cross relaxations (CR), thus providing longer lifetimes. More effort is needed to better understand the sintering mechanisms by SPS in transparent GC systems and optimize their final optical performance.

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Transparent SiO2-GdF3 sol–gel nano-glass ceramics for optical applications

Cited by 30 publications

References 40 publications

Transparent Glass-Ceramics Produced by Sol-Gel: A Suitable Alternative for Photonic Materials

Transparent Glass-Ceramics Produced by Sol-Gel: A Suitable Alternative for Photonic Materials

Transparent Sol-Gel Oxyfluoride Glass-Ceramics with High Crystalline Fraction and Study of RE Incorporation

Glass-Ceramics Processed by Spark Plasma Sintering (SPS) for Optical Applications

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