Phenomenon of activator segregation and its spectroscopic consequences

Karapetyan, G. O.; Maksimov, L. V.

doi:10.1007/bf00613406

Cited by 13 publications

(13 citation statements)

References 17 publications

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“…The fact that the experimentally determined capture volume of electronic color centers for Eu 3+ in fluoroaluminate glasses, (31.6 ± 0.5) × 10 -20 cm 3 [11], is almost two orders of magnitude larger than that for Eu 3+ in phosphate glasses, (0.5 ± 0.1) × 10 -20 cm 3 [13], suggests that the activator distribution in the fluoroaluminate glasses is not fully random, in line with the ideas discussed in [16,17]. Consequently, the capture volume is a…”

Section: Introductionsupporting

confidence: 56%

“…At the same time, the tendency for activator ions to accumulate in the most polar regions [17] persists, as evidenced by the fact that, at low Tb concentrations (below about 0.25 × 10 20 cm -3 ), the intensity of the EPR signal from P in Ba(PO 3 ) 2 glass slightly deviates from linearity in the plot of ln( ) versus n Tb . Such microregions in phosphate glasses may be due to the accumulation of defects arising from the transformation of covalent bonding into ionic, with no significant reduction in energy [25].…”

Section: Normalized Intensitymentioning

confidence: 90%

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Rare-Earth-Activated Fluorophosphate Glasses: Local Environment of the Activator and Capture Volume Model

2005

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Data are presented on the induced optical absorption and EPR in Ba(PO 3 ) 2 -MgF 2 glasses activated with Tb 2 O 3 and Eu 2 O 3 . The effect of activator concentration on the EPR spectra of the ê and ê centers in glasses differing in fluoride content is analyzed. The results indicate that fluorophosphate glasses can be characterized by two capture volumes which may differ several times, depending on the activator concentration. At low activator concentrations, corresponding to the largest capture volume, the activator ions seem to be in a phosphate environment. The maximum Tb 3+ concentration is comparable to the Eu 3+ concentration at which the luminescence spectrum points to a phosphate environment of the rare-earth ion. O 4 2-O 3 2-

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Section: Introductionsupporting

confidence: 56%

Section: Normalized Intensitymentioning

confidence: 90%

Rare-Earth-Activated Fluorophosphate Glasses: Local Environment of the Activator and Capture Volume Model

2005

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“…As was noted above, the capture volumes for Eu 3+ ions in phosphate and fluoroaluminate glasses differ by two orders of magnitude (compare glasses 2 and 7 in Table 2). This suggests an increased local concentration of dopant ions in the most polar microregions characterized by a chemical differentiation in fluoroaluminate glasses [33]. Moreover, since there exist two concentration ranges in which the capture volumes in fluorophosphate glasses differ by a factor of 5.0-6.6 ( Fig.…”

Section: Resultsmentioning

confidence: 98%

A model of the capture volume of free carriers in fluorophosphate glasses doped with terbium

Bocharova

2005

Glass Phys Chem

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INTRODUCTIONThe particular interest expressed by researchers in the study of the behavior of rare-earth ions in glassforming matrices has stemmed, to a large extent, from new possibilities offered by optical fiber amplifiers based on Er 3+ , Pr 3+ , and Nd 3+ ions [1,2]. Until recently, many attempts have been made to elucidate the nearest environment of dopant ions and to determine their spatial distribution in different matrices [3][4][5]. In our opinion, investigation into the properties of fluorophosphate and fluoride glasses doped with rare-earth ions holds the greatest interest today. This is associated with the unique spectroscopic properties exhibited by rare-earth ions in these matrices (specifically with the high efficiency of excitation energy transfer from Yb 3+ ions to Er 3+ ions as compared to silicate and borate matrices [6,7]), on the one hand, and with the low energy of phonons in the fluoride matrix (which makes it promising for use in fabricating fibers with low losses in the IR range [1, 2]), on the other hand.Traditionally, the local environment of dopant ions has been examined using spectroscopic methods, including the study of luminescence spectra, luminescence decay kinetics, and IR absorption spectra. In particular, Hiroyuku et al. [8] investigated the Eu 3+ luminescence spectra of fluoroaluminate and fluorophosphate glasses (containing 1 mol % EuF 3 ) at 80 K and revealed that the nearest environment of Eu 3+ ions involves oxygen. Kolobkov et al. [9] refined the dependence of the local environment of rare-earth ions in glasses of the MgF 2 -(0.6CaF 2 + 0.4AlF 3 )-Ba(PO 3 ) 2 system on the content of the fluoride component in the initial matrix. In [9], the authors analyzed the Eu 3+ and Nd 3+ luminescence spectra and nonradiative nonresonant energy transfer between Er 3+ and Ho 3+ ions and established that, in fluorophosphate glasses containing up to 40-50 mol % of fluorides, the nearest environment of rare-earth ions is predominantly formed by phosphate groupings. In this case, the dopant content was equal to 1 wt % (5 wt % for Eu 2 O 3 ). More recently, Zhmyreva et al.[10] studied the vibronic and Raman spectra of doped glasses in systems with a similar composition (the Eu 2 O 3 content was 5 wt %). It was shown that the presence of fluorophosphate groups in the vicinity of rare-earth ions manifests itself in the spectral characteristics of glasses containing 30 and 10 mol % of barium metaphosphate and that, at a higher barium metaphosphate content, the dopant ions are incorporated into regions in the immediate vicinity of the phosphate structural units of the glass network. Karapetyan et al. [11] observed the concentration quenching of neodymium luminescence in glasses of the MgCaSrBaAl 2 F 14 -Ba(PO 3 ) 2 pseudobinary system. It was found that the concentration quenching limits for glasses containing 60 and 7 mol % Ba(PO 3 ) 2 are equal to 2 × 10 20 and 1 × 10 20 ions cm -3 , respectively. Comparison of the results obtained with the data on the absorption spectra allowed those aut...

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“…The former are characterized by the occurrence of regions enriched in the`Si\O − Me + and like polar terminal groups and the ones depleted in such groups (the difference disappearing at compositions close to the alkali/alkaline earth disilicates, Me 2 O×2SiO 2 and MeO ×2SiO 2 ). As a relult, the well-known phenomenon of so-called activator segregation (see, for example, [25]) occurs: the triply charged ions of rare earth and other activators tend to be located mostly in regions enriched in the polar groups. In the matrix composition of PTR glasses (see Experimental), the total content of components producing the polar groups (such as Na 2 O, NaF, and ZnO) is by orders greater than the cerium content.…”

Section: Resultsmentioning

confidence: 99%

Quantitative UV–VIS spectroscopic studies of photo-thermo-refractive glasses. II. Manifestations of Ce3+ and Ce(IV) valence states in the UV absorption spectrum of cerium-doped photo-thermo-refractive matrix glasses

Efimov

Ignatiev

Никоноров

et al. 2013

Journal of Non-Crystalline Solids

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Phenomenon of activator segregation and its spectroscopic consequences

Cited by 13 publications

References 17 publications

Rare-Earth-Activated Fluorophosphate Glasses: Local Environment of the Activator and Capture Volume Model

Rare-Earth-Activated Fluorophosphate Glasses: Local Environment of the Activator and Capture Volume Model

A model of the capture volume of free carriers in fluorophosphate glasses doped with terbium

Quantitative UV–VIS spectroscopic studies of photo-thermo-refractive glasses. II. Manifestations of Ce3+ and Ce(IV) valence states in the UV absorption spectrum of cerium-doped photo-thermo-refractive matrix glasses

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