Europium (II)-Doped CaF2 Nanocrystals in Sol-Gel Derived Glass-Ceramic: Luminescence and EPR Spectroscopy Investigations

The remarkable properties of Eu2+-activated phosphors, related to the broad and intense luminescence of Eu2+ ions, showed a high potential for a wide range of optical-related applications. Oxy-fluoride glass-ceramic containing Europium (II)-doped CaF2 nanocrystals embedded in silica matrix were prod...

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Bibliographic Details
Published in:Nanomaterials (Basel, Switzerland) Switzerland), 2022-08, Vol.12 (17), p.3016
Main Authors: Secu, Corina, Rostas, Arpad-Mihai, Secu, Mihail
Format: Article
Language:English
Subjects:
Acids
Annealing
Atmosphere
CaF2
Calcium fluoride
Ceramics
Crystals
Europium
Fluorides
glass ceramic
Glass ceramics
Investigations
Ions
Irradiation
Luminescence
Nanocrystals
Nanophosphors
Optical properties
Phosphors
Photoelectron spectroscopy
Photoelectrons
Photoluminescence
Photons
Radiation detectors
Recombination
Silica
Sol-gel processes
Spectroscopy
Temperature
Thermoluminescence
X ray irradiation
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Summary:The remarkable properties of Eu2+-activated phosphors, related to the broad and intense luminescence of Eu2+ ions, showed a high potential for a wide range of optical-related applications. Oxy-fluoride glass-ceramic containing Europium (II)-doped CaF2 nanocrystals embedded in silica matrix were produced in two steps: glass-ceramization in air at 800° with Eu3+-doped CaF2 nanocrystals embedded followed by Eu3+ to Eu2+ reduction during annealing in reducing atmosphere. The broad, blue luminescence band at 425 nm and with the long, weak tail in the visible range is assigned to the d → f type transition of the Eu2+ located inside the CaF2 nanocrystals in substitutional and perturbed sites, respectively; the photoluminescence quantum yield was about 0.76. The X-ray photoelectron spectroscopy and Electron paramagnetic spectroscopy confirmed the presence of Eu2+ inside the CaF2 nanocrystals. Thermoluminescence curves recorded after X-ray irradiation of un-doped and Eu2+-doped glass-ceramics showed a single dominant glow peak at 85 °C related to the recombination between F centers and Eu2+ related hole within the CaF2 nanocrystals. The applicability of the procedure can be tested to obtain an oxy-fluoride glass-ceramic doped with other divalent ions such as Sm2+, Yb2+, as nanophosphors for radiation detector or photonics-related applications.
ISSN:2079-4991
2079-4991
DOI:10.3390/nano12173016