研究目的
To synthesize and characterize photoluminescent materials based on NaF–Al2O3–P2O5 glasses doped with europium, with the aim of controlling the Eu2+/Eu3+ ratio to achieve tunable emission spectra for potential use in white LEDs.
研究成果
The synthesis conditions effectively control the Eu2+/Eu3+ ratio, enabling tunable photoluminescence spectra from red to white. The smooth spectra resemble natural light, making the materials promising for white LED applications. Future work should measure CRI and efficacy and explore other glass matrices.
研究不足
XPS is a surface method, potentially overestimating Eu3+ concentration due to surface oxidation. The study is limited to one glass composition; other matrices were not explored. Exact color rendering index and luminous efficacy were not measured.
1：Experimental Design and Method Selection:
The study involved synthesizing glass samples with varying melting times and temperatures under reducing conditions to control the oxidation state of europium. Characterization methods included XRD, DTA, XPS, photoluminescence spectroscopy, decay time measurements, and absorption spectroscopy.
2：Sample Selection and Data Sources:
Samples were prepared from mixtures of NaF, Al2O3, NH4H2PO4, and Eu2O3, doped with 1 wt% europium. Three samples (A, B, C) were synthesized with different melting parameters (time: 5-15 min, temperature: 1100-1350 °C).
3：List of Experimental Equipment and Materials:
Equipment included a double crucible setup for synthesis, Philips X'Pert Pro diffractometer, TA Q600 DTA apparatus, Escalab 250 Xi XPS spectrometer, He-Cd laser, Andor Shamrock SR-303i-B spectrometer, Pico Harp 300 system, Excelitas AQRH module, Varian Cary 50 UV-Vis spectrophotometer. Materials included NaF (>99%), Al2O3 (p.a.), NH4H2PO4 (99.5%), Eu2O3 (99.9%), activated charcoal.
4：5%), Eu2O3 (9%), activated charcoal. Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The synthesis used a double crucible technique with charcoal to create a reducing atmosphere. Melts were quenched between stainless-steel plates. Characterization involved XRD for amorphousness check, DTA for thermal properties, XPS for oxidation state analysis, PL measurements with 325 nm excitation, decay time measurements with 375 nm pulsed laser, and absorption spectroscopy.
5：Data Analysis Methods:
XPS data were analyzed using Avantage software with Gaussian-Lorentzian functions. PL spectra were deconvoluted using Fityk 0.9.8 software with Gaussian profiles. Decay curves were fitted with multi-exponential functions.
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Escalab 250 Xi
250 Xi
Thermo Fisher Scientific
Used for high-resolution XPS studies to determine Eu oxidation states.
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Andor Shamrock SR-303i-B spectrometer
SR-303i-B
Andor
Used to acquire photoluminescence spectra.
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Andor iDus CCD camera
iDus
Andor
Used with the spectrometer for detection.
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Excelitas AQRH photon counting module
AQRH
Excelitas
Equipped with avalanche diode for photon counting in decay time measurements.
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Philips X'Pert Pro diffractometer
X'Pert Pro
Philips
Used for XRD measurements to check amorphousness of samples.
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TA Q600 apparatus
Q600
TA
Used for DTA measurements to determine glass transition and crystallization temperatures.
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He-Cd laser
Used as excitation source for photoluminescence measurements.
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Pico Harp 300
300
Pico
Used for time-resolved photoluminescence measurements.
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Varian Cary 50 UV-Vis Spectrophotometer
Cary 50
Varian
Used for absorption measurements.
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Double crucible
Used in synthesis to create reducing atmosphere with charcoal.
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NaF
Sigma-Aldrich
Initial reagent for synthesis.
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Al2O3
POCh (Polish Chemicals)
Initial reagent for synthesis.
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NH4H2PO4
POCh
Initial reagent for synthesis.
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Eu2O3
POCh
Source of europium dopant.
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Activated charcoal
Used in outer crucible to create reducing atmosphere.
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Stainless-steel plates
Used for melt-quenching of samples.
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Black plate with carbon tape
Used to fix samples during PL measurements.
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Cyanoacrylate glue
Used to attach samples to holders in absorption measurements.
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