The luminescence efficiency of ions with broad-band excitation in borate glasses

Verwey, J.W.M.; Blasse, G.

doi:10.1016/0254-0584(90)90010-8

Cited by 46 publications

(20 citation statements)

References 14 publications

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“…For Eu 3+ in BLA and BLACN glasses, Fig. 3a, the observed broad band is ascribed to a charge-transfer transition, which has been shown to play the role of a quenching state [10]. For Eu 3+ in BLANB glasses, Fig.…”

Section: Resultsmentioning

confidence: 88%

“…The most efficient luminescence occurs in niobyl groups [7], i.e., an Nb-O group with a short bond distance, approximately 0.17 nm. Structurally isolated NbO 6 octahedra, such as in ordered perovskites and in MgNb 2 (P 2 O 7 ) 3 , are not efficient luminescent centers [10], whereas isolated distorted niobate groups, such as in LaNbO 4 , where the Nb(V) has a 4+2 coordination, provide very efficient centers [6]. Edge-or face-shared NbO 6 octahedral groups show efficient luminescence with a large D ST ; while corner-sharing of NbO 6 groups leads to shift of the optical absorption to lower energies, exciton delocalization, smaller D ST ; lower quenching temperatures, energy migration and consequently luminescence quenching [6].…”

Section: Resultsmentioning

confidence: 99%

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Luminescence and energy transfer in La2O3–Nb2O5–B2O3:M3+ (M=Bi, Eu, Dy) glasses

Fragoso

Donegá

Longo

2003

Journal of Luminescence

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The luminescence and energy transfer processes in La 2 O 3-Nb 2 O 5-B 2 O 3 :M 3+ (M=Bi, Eu, Dy) glasses were investigated using luminescence spectroscopy (excitation and emission, down to 4.2 K) and decay time measurements at room temperature. The observation of niobate luminescence implies a considerable degree of short-and intermediaterange order in these glasses. Energy transfer from the niobate groups to the lanthanide ions was observed for Eu 3+ , but not for Dy 3+ , suggesting that the energy transfer process occurs to the charge-transfer state of the Eu 3+ ion, rather than to its f-levels. Inter-Eu 3+ energy transfer was negligible in the concentration range investigated (up to 3 mol%). In contrast, cross-relaxation processes between Dy 3+ ions were active at concentrations as low as 0.5 mol%. In the Bi 3+ doped glasses the energy transfer was observed from the Bi 3+ excited levels to the oxygen deficient niobate groups.

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Luminescence and energy transfer in La2O3–Nb2O5–B2O3:M3+ (M=Bi, Eu, Dy) glasses

Fragoso

Donegá

Longo

2003

Journal of Luminescence

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“…The most efficient luminescence occurs in niobyl groups as in the Nb-O group with a short bond distance, of approximately 0.17 nm [17]. Structurally isolated NbO 6 octahedra are not efficient luminescent centers [18], whereas isolated distorted niobate groups, such as in LaNbO 4 , where the Nb(V) has a 4 + 2 coordination, provide very efficient centers. The closer the Nb-O-Nb angles are to 180 the more pronounced the effects of the NbO 6 condensation become [16,17,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Joya

Barba-Ortega

Raba-Páez

et al. 2017

Metals

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Abstract:In this work, a set of nanoparticles of Nb 2 O 5 nanoparticles were grown by both the Pechini and the sol-gel methods. The amorphous materials were calcined at 650 • C or at 750 • C. X-ray diffraction, scanning electron microscopy, luminescence and Raman spectroscopy were used in order to characterize the materials. From the study, it is possible to state that the method of production of nanoparticles, beyond the temperature of synthesis, has a great influence on whether the phase produced is hexagonal or orthorhombic. Additionally, compared to de Sol-gel method, the Pechini method produced samples with smaller particle sizes. The photoluminescence spectra of niobium pentoxide nanostructure materials show that the emission peaks are positioned between 334 to 809 nm and there is a change of intensity which varies depending on the synthesis route used. High pressure Raman spectra at room temperature were obtained from two samples grown by the sol-gel method. Up to 6 GPa, where it is possible to observe the Raman bands, no modification other than the increase of disorder was observed, and this can be associated with a change of phase.

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“…The most efficient luminescence occurs in niobyl groups [4], i.e., an Nb-O group with a short bond distance, %0.17 nm. Structurally isolated NbO 6 octahedra, such as in ordered perovskites and in MgNb 2 (P 2 O 7 ) 3 are not efficient luminescent centers [7], whereas isolated distorted niobate groups, such as in LaNbO 4 , where the Nb(V) has a 4 + 2 coordination, provide very efficient centers [3]. Edge-or face-shared NbO 6 maxima; while corner-sharing of NbO 6 groups leads to a shift of the optical absorption to lower energies, exciton delocalization, smaller D ST ; lower quenching temperatures, energy migration and consequently luminescence quenching [3].…”

Section: Introductionmentioning

confidence: 99%

A structural model of La2O3–Nb2O5–B2O3 glasses based upon infrared and luminescence spectroscopy and quantum chemical calculations

Fragoso

Donegá

Longo

2005

Journal of Non-Crystalline Solids

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Infrared spectra of 20La 2 O 3 -xNb 2 O 5 -(80 À x)B 2 O 3 , 24La 2 O 3 -xNb 2 O 5 -(76 À x)B 2 O 3 and 28La 2 O 3 -xNb 2 O 5 -(72 À x)B 2 O 3 glasses, with x = 1, 5, 10, 15 and 20, have been obtained. Also, the luminescence spectrum of the 28La 2 O 3 -10Nb 2 O 5 -62B 2 O 3 sample has been obtained. Density functional theory (DFT-B3LYP) calculations on clusters containing BO 3 , BO 4 , NbO 6 , edge-sharing NbO 6 -NbO 6 , edge-sharing NbO 6 -NbO 6 (niobyl), and corner-sharing NbO 6 -NbO 6 groups have been used to aid the infrared spectra assignments. From these data it was possible to propose a structural model for the La 2 O 3 -Nb 2 O 5 -B 2 O 3 glasses that is consistent with all the spectroscopic and theoretical results as well with previous luminescence study of similar samples. Briefly, this model consists of distorted NbO 6 octahedral groups replacing the BO 4 tetrahedral groups giving rise to non-bridging oxygen ions and distorted NbO 6 chains. These chains change from edge-sharing to corner-sharing distorted NbO 6 octahedra depending upon the La 2 O 3 concentration. For La 2 O 3 concentration larger than 28 mol% there seems to be a segregation of La(III) to another domain, restoring the structure observed for samples with La 2 O 3 concentrations lower than 20 mol%.

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The luminescence efficiency of ions with broad-band excitation in borate glasses

Cited by 46 publications

References 14 publications

Luminescence and energy transfer in La2O3–Nb2O5–B2O3:M3+ (M=Bi, Eu, Dy) glasses

Luminescence and energy transfer in La2O3–Nb2O5–B2O3:M3+ (M=Bi, Eu, Dy) glasses

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

A structural model of La2O3–Nb2O5–B2O3 glasses based upon infrared and luminescence spectroscopy and quantum chemical calculations

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