Luminescence and energy transfer in the columbite structure

Blasse, G.; Leur, M.G.J. van

doi:10.1016/0025-5408(85)90202-8

Cited by 37 publications

(8 citation statements)

References 20 publications

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“…These results are very close to those observed for crystalline CaNb 2 O 6 , namely k exc = 260 nm, k em = 460 nm and D ST = 16 000 cm À1 , which has a columbite structure characterized by edge-sharing distorted NbO 6 octahedra [15].…”

Section: Discussionsupporting

confidence: 86%

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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Section: Discussionsupporting

confidence: 86%

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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“…The transitions originating from the 1 D 2 level dominate the spectrum. When the system is excited at a wavelength of 270 nm, the luminescence (dashed curve) is dominated by the broad band extending from 26,670 cm À1 (375 nm) to 16,670 cm À1 (600 nm) related to the host and attributed to STE emission [9]. The dips present in this band are related to Pr 3+ re-absorption and attributed to transitions form the ground state 3 H 4 to the excited 3 P 0, 3 P 1 , 1 I 6 and 3 P 2 states.…”

Section: Resultsmentioning

confidence: 99%

“…In this contribution we present a study of the luminescence of Ca(NbO 3 ) 2 :Pr 3+ , in high-pressure conditions and using time-resolved spectroscopic techniques. In particular, we show that upon host excitation the luminescence is dominated by a broad band emission related to self-trapped exciton (STE) recombination [9], and Pr 3+ ions are excited due to re-absorption of the light emitted by STE recombination in the Ca(NbO 3 ) 2 host. The effect of high pressure on the luminescence from the excited levels of Pr 3+ is discussed.…”

Section: Introductionmentioning

confidence: 99%

Luminescence of Ca(NbO3)2:Pr3+ at ambient and high hydrostatic pressure

Mahlik

Grinberg

Kaminskii

et al. 2009

Journal of Luminescence

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“…Calcium niobate (CaNb 2 O 6 ) has an orthorhombic crystal structure with cell parameters of a =14.962, b =5.752, and c =5.204 Å 13 . In the literature, CaNb 2 O 6 has been investigated as a host material for phosphors 14–16 and microwave dielectrics 17 . The photocatalytic properties of bulk CaNb 2 O 6 powder for the degradation of rhodamine B dye solution under UV irradiation were studied by An et al 18 They found, however, that the photocatalytic activity of bulk CaNb 2 O 6 powder was low because of large particle sizes and poor optical absorption properties.…”

Section: Introductionmentioning

confidence: 99%

Preparation, Characterization, and Photocatalytic Properties of CaNb₂O₆ Nanoparticles

Cho¹,

Bae²,

Yim³

et al. 2009

Journal of the American Ceramic Society

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CaNb2O6 nanoparticles with a size range of 30–50 nm were synthesized by heat treatment at 600°C after a solvothermal process and their optical and photocatalytic properties were investigated. The prepared powders were characterized by X‐ray powder diffractometer, field‐emission scanning electron microscope, transmission electron microscope, UV‐Vis diffuse reflectance spectroscopy, Fluorescence spectroscopy, and Raman spectroscopy. Compared with a powder of the same material prepared by a solid‐state reaction (SS) method, the nanoparticles exhibited a higher Brunauer–Emmett–Teller (BET) surface area, more efficient light absorption, and enhanced photocatalytic activity for producing H2 from pure water under UV irradiation. The photoluminescence spectra revealed that a radiative recombination process is dominant in the powder prepared by the SS method (strong blue emission at 300 K) under UV light irradiation, while no obvious emission was observed in the nanoparticles. This decrease of the radiative recombination as well as the higher optical absorption ability and higher BET surface area resulting from the reduced dimensionality led to enhanced photocatalytic activity of the nanoparticles.

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Luminescence and energy transfer in the columbite structure

Cited by 37 publications

References 20 publications

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

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

Luminescence of Ca(NbO3)2:Pr3+ at ambient and high hydrostatic pressure

Preparation, Characterization, and Photocatalytic Properties of CaNb₂O₆ Nanoparticles

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Luminescence and energy transfer in the columbite structure

Cited by 37 publications

References 20 publications

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

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

Luminescence of Ca(NbO3)2:Pr3+ at ambient and high hydrostatic pressure

Preparation, Characterization, and Photocatalytic Properties of CaNb2O6 Nanoparticles

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Preparation, Characterization, and Photocatalytic Properties of CaNb₂O₆ Nanoparticles