Analysis of rare-earth ion spatial distribution in fluorophosphate glasses in terms of segregation phenomenon

Bocharova, T. V.; Adam, Jean-Luc; Karapetyan, G. O.; Smektala, F.; Mironov, Andrey E.; Tagil’tseva, N. O.

doi:10.1016/j.jpcs.2007.03.011

Cited by 8 publications

(11 citation statements)

References 5 publications

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“…As the non-bridiging oxygen atoms of the phosphate ligands generate higher ligand field strength and bonding covalency than the fluoride ligands, higher α values are expected for phosphate glasses than for fluoride glasses in general. A review of the literature on Eu-doped fluoride phosphate glasses indicates α values near unity in glasses with high F contents and values near 2.5 to 3.0 in pure phosphate glasses [18][19][20][21][22][23]68,[76][77][78][79]. In the present system we observe α-values near 1.6, 1.9, and 2.3 in glasses with x = 25, 20, and 15, respectively, containing 1.0 % Eu.…”

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confidence: 50%

“…Fluoroaluminophosphate glasses play an important role in this endeavor, and numerous promising RE-doped compositions have been developed, characterized with regard to their local structures and photophysical properties, and functionally tested. − Nevertheless, the local bonding preferences of the emitting rare-earth ions in these glasses are still uncertain. Because some of the transitions of Eu 3+ are particularly sensitive to the ligand environment, detailed spectroscopic studies of Eu-doped glasses have been carried out with systematic compositional variation. − Qualitative insights have also come from phonon sideband intensities , and Mössbauer spectra, whereas the method of electron spin resonance utilizing rare-earth spin probes has been greatly under-utilized in this field . Unfortunately, rare-earth ion environments cannot be studied directly by standard solid-state NMR methods, as their 4f n paramagnetism broadens their NMR signals beyond detectability.…”

Section: Introductionmentioning

confidence: 99%

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Network Structure and Rare-Earth Ion Local Environments in Fluoride Phosphate Photonic Glasses Studied by Solid-State NMR and Electron Paramagnetic Resonance Spectroscopies

et al. 2015

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A detailed structural investigation of a series of fluoride phosphate laser glasses with nominal composition 25BaF 2 -25SrF 2 -(30-x)Al(PO 3 ) 3 -xAlF 3 -(20-z)YF 3 :zREF 3 with x = 25, 20, 15 and 10, RE = Yb and Eu and 0 ≤ z ≤ 1.0 has been conducted, using Raman, solidstate nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies. The network structure is dominated by the preferred formation of aluminum-to-phosphorus linkages, which have been quantified by means of 27 Al/ 31 P NMR double resonance techniques. The fluoride ions are found in mixed Al/Y/Ba/Sr environments accommodating the luminescent dopant species as well. The local environments of the rare-earth species have been studied by pulsed EPR spectroscopy of the Yb 3+ spin probe (S = ½), revealing composition dependent echo-detected lineshapes, and strong hyperfine coupling with 19 F nuclei in hyperfine sublevel correlation (HYSCORE) spectra consistent with the formation of Yb 3+ -F bonds. In addition, photoluminescence spectra of Eu 3+ -doped samples reveal that the 7 F 2 -> 5 D 0 / 7 F 1 -> 5 D 0 transition intensity ratio, the normalized phonon sideband intensities in the excitation spectra as well as excited state lifetimes are systematically dependent on fluoride content.Altogether, these results indicate that the rare-earth ions are found in a mixed fluoride/phosphate environment, to which the fluoride ions make the dominant contribution. Nevertheless, even at the highest fluoride levels (x = 25) the data suggest residual rare-earth-phosphate coordination.

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supporting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Network Structure and Rare-Earth Ion Local Environments in Fluoride Phosphate Photonic Glasses Studied by Solid-State NMR and Electron Paramagnetic Resonance Spectroscopies

et al. 2015

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“…Therefore, the ratio α = I ( 5 D 0 → 7 F 2 )/ I ( 5 D 0 → 7 F 1 ) is usually employed as an indicator of the ligand environment of the Eu 3+ site. , Higher α values are expected for phosphate glasses than for fluoride glasses given the higher covalency of the RE–O bond, which results in larger admixture of excited electronic states and consequently higher transition probabilities. For Eu 3+ -doped fluoride phosphate glasses α values are found near unity in glasses with high F contents, whereas they are found near 2.5–4.0 in pure phosphate glasses. − In the present system we observe α-values near 1.9, 2.4, and 2.7 for samples A , B and C , respectively and around 3.1 ± 0.2 for samples D , F and G . Thus, our data suggest a phosphate/fluoride mixed local environment for the Eu 3+ ions in these glasses, being fluoride rich for sample A , intermediate in samples B and C , and phosphate richer for samples D , F and G .…”

Section: Results Data Analysis and Interpretationmentioning

confidence: 41%

Structure–Property Relations in Fluorophosphate Glasses: An Integrated Spectroscopic Strategy

et al. 2017

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A detailed structural investigation of a series of fluoride phosphate glasses with nominal compositions 25BaF2-25SrF2–(30–x)Al(PO3)3–xAlF3–(20–z)ScF3:zREF3 with x = 25, 20, and 15, RE = Yb and Eu, and 0 ≤ z ≤ 1.0, and of a Sc-free set of glasses with compositions w[80(Ba/Sr)F2–20AlF3]–(1–w)[80Ba(PO3)2–20Al(PO3)3] (w = 25, 50, 75), doped with 0.2 mol % Yb3+ or Eu3+, has been conducted. As indicated by Raman scattering and solid state NMR, the network structure is dominated by aluminum–oxygen-phosphorus linkages, which can be quantified by means of 27Al/31P NMR double resonance techniques. The ligand environment of the rare-earth ions is studied by (1) 45Sc NMR of the diamagnetic mimic Sc3+, (2) pulsed X-band EPR spectroscopy of Yb3+ spin probes, and (3) excitation and emission spectroscopy of Eu3+ dopants. The rare-earth ions are found in a mixed environment of fluoride and phosphate ions, which changes systematically as a function of glass composition. In the Sc-containing glasses the quantitative makeup of this ligand environment has been determined by 45Sc{19F} and 45Sc{31P} rotational echo double resonance (REDOR). Comparison of the P- to F-ligand ratio with the batch composition indicates that the Sc3+ ions show a clear preference for phosphate over fluoride ion ligation. These REDOR results were correlated with Yb3+ EPR data, the intensity ratio of Eu3+ transitions 5D0 → 7F2 to 5D0 → 7F1, and the lifetime values of the Eu3+ emitting level 5D0. As a result, it was possible to obtain a global interpretation in terms of the associated quantitative ligand distribution (fluoride versus phosphate) in the first coordination sphere of the rare earth ions. The calibration of EPR and luminescence spectra on the basis of such solid state NMR data defines a new spectroscopic strategy for characterizing the rare-earth local environments in promising laser glasses.

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“…Therefore, we can use the ratio α = I ( 5 D 0 → 7 F 2 )/ I ( 5 D 0 → 7 F 1 ) to characterize the type of ligand environment present at the Eu 3+ site. Owing to the higher covalency of the RE–O bond, which results in a stronger admixture of excited electronic states and consequently higher transition probabilities, the α values are found to be significantly higher for phosphate glasses (typically between 2.5 and 4.0) than for fluoride glasses (near unity). − The α values in the present system are found near 0.8, 1.0, 1.2, and 1.6 for the glasses ISBZ, 5InPF, 10InPF, and 15InPF, respectively, and values near 0.9, 1.0, 1.3, and 1.6 for the glasses ISBZ_Sc, 5InPF_Sc, 10InPF_Sc, and 15InPF_Sc, respectively. The values are comparable with previous data reported by Messaddeq et al in the ternary system In(PO 3 ) 3 –InF 3 –BaF 2 .…”

Section: Results Data Analysis and Interpretationmentioning

confidence: 59%

Compositional Optimization of Emission Properties for Rare-Earth Doped Fluoride Phosphate Glasses: Structural Investigations via NMR, EPR, and Optical Spectroscopies

et al. 2019

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A detailed structural investigation of two series of fluoride phosphate glasses with nominal compositions 20BaF2–20SrF2–20ZnF2–xIn(PO3)3–(40 – x)InF3 (x = 0, 5, 10, and 15) and 20BaF2–20SrF2–20ZnF2–10ScF3–xIn(PO3)3–(30 – x)InF3 (x = 0, 10, 15, 20), both doped with either 0.2 mol % Yb3+ or 0.5 mol % Eu3+, has been conducted. As indicated by Raman scattering and solid-state NMR, the network structure is dominated by six-coordinated In3+, orthophosphate Q(0) species, and the (near) absence of P–O–P connectivity. The ligand environment of the rare-earth ions is studied by (1) 45Sc NMR of the diamagnetic mimic Sc3+, (2) echo-detected field-sweep EPR spectra at the X-band, using Yb3+ spin probes, and (3) excitation and emission spectroscopy of Eu3+ dopants. 45Sc{31P} rotational echo double resonance (REDOR) results, the ratio of the Eu3+ 5D0 → 7F2 to 5D0 → 7F1 emission intensities, the lifetime values of the Eu3+ emitting level 5D0, as well as the g factor measured by EPR spectroscopy consistently indicate that the fluoride ligands strongly dominate in the first coordination sphere of the rare-earth ions. This result stands in contrast to previous studies on aluminofluorophosphate glasses with similar compositions that show mixed ligation of the rare-earth ions by fluoride and phosphate ions. Thus, by substituting aluminum by its homologue indium one can achieve the original design goal of fluoride phosphate glasses, which is the creation of a framework structure dominated by oxide, while the local environment of the RE emitting ion is dominated by fluoride ligands, so as to improve their emissive properties. The results also illustrate the successful use of the previously developed combined NMR/EPR/optical characterization strategy for the design of optimized matrices for rare-earth ion emitters.

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Analysis of rare-earth ion spatial distribution in fluorophosphate glasses in terms of segregation phenomenon

Cited by 8 publications

References 5 publications

Network Structure and Rare-Earth Ion Local Environments in Fluoride Phosphate Photonic Glasses Studied by Solid-State NMR and Electron Paramagnetic Resonance Spectroscopies

Network Structure and Rare-Earth Ion Local Environments in Fluoride Phosphate Photonic Glasses Studied by Solid-State NMR and Electron Paramagnetic Resonance Spectroscopies

Structure–Property Relations in Fluorophosphate Glasses: An Integrated Spectroscopic Strategy

Compositional Optimization of Emission Properties for Rare-Earth Doped Fluoride Phosphate Glasses: Structural Investigations via NMR, EPR, and Optical Spectroscopies

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