Novel green emitting Tb3+ doped KCaF3 phosphor for WLEDs and TLD applications

Kameshwaran, R.; Annalakshmi, O.; Aravinth, K.; Bhargav, P. Balaji

doi:10.1016/j.ceramint.2022.10.316

Cited by 11 publications

(6 citation statements)

References 38 publications

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“…The obtained curves are exponential in nature. Figure 7b,c shows a good fit with the exponential decay 2 line with R 2 = 0.99, which was obtained using the following equation [36]:…”

Section: Pl Studymentioning

confidence: 78%

“…The obtained curves are exponential in nature. Figure 7b,c shows a good fit with the exponential decay 2 line with R 2 = 0.99, which was obtained using the following equation [36]:

I ()(, t) goodbreak= A_{1} e^{\frac{- t}{τ_{1}}} goodbreak+ A_{2} e^{\frac{- t}{τ_{2}}}

where A 1 and A 2 represent fitting constants, τ 1 and τ 2 represent the decay time of the exponential factors, I is the express intensity, and t is the time. The average lifetime of luminescence decay ( τ ) for K 2 LiAlF 6 :3%Mn 4+ was 8.59 and 8.29 ms for the linear and logarithmic scales of intensity, respectively, using the following formula [37]:

τ goodbreak= \frac{{A_{1} τ_{1}}^{2} + A_{2} {τ_{2}}^{2}}{A_{1} τ_{1} + A_{2} τ_{2}}

…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and study of luminescence properties of a deep red–emitting phosphor K₂LiAlF₆:Mn⁴⁺ for plant cultivation

Bawanthade,

Mistry,

Ugemuge

et al. 2023

Luminescence

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Light is the most important component in plant growth and development. This study synthesised a novel Mn4+‐doped K2LiAlF6 red‐emitting phosphor using the coprecipitation method. We observed that on addition of dopant Mn4+ ions to the host K2LiAlF6, its phase changed from rhombohedral to cubic due to the change in the lattice position of the atoms. When the atoms are excited at 468 nm, the K2LiAlF6:Mn4+ phosphor exhibited a red emission band ranging from 630 to 700 nm, centred at 638 nm, which matched well with the absorption spectra of phytochrome PR. The critical quenching content of Mn4+ ions was ~3 mol%. The critical distance between Mn4+ ions was determined to be 19.724 Å, and non‐radiative energy transfer among the nearest‐neighbour Mn4+ ions was the mechanism used for the concentration quenching effect. The Commission International de l'Eclairage (CIE) chromaticity coordinates of the K2LiAlF6:0.03 Mn4+ sample were (x = 0.7162, y = 0.2837). The luminescence mean decay time was calculated to be 8.29 ms. These results demonstrated the promising prospect of K2LiAlF6:Mn4+ as a red‐emitting phosphor for application in red light‐emitting diodes for plant cultivation.

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“…The obtained curves are exponential in nature. Figure 7b,c shows a good fit with the exponential decay 2 line with R 2 = 0.99, which was obtained using the following equation [36]:…”

Section: Pl Studymentioning

confidence: 78%

“…The obtained curves are exponential in nature. Figure 7b,c shows a good fit with the exponential decay 2 line with R 2 = 0.99, which was obtained using the following equation [36]:

I ()(, t) goodbreak= A_{1} e^{\frac{- t}{τ_{1}}} goodbreak+ A_{2} e^{\frac{- t}{τ_{2}}}

τ goodbreak= \frac{{A_{1} τ_{1}}^{2} + A_{2} {τ_{2}}^{2}}{A_{1} τ_{1} + A_{2} τ_{2}}

…”

Section: Resultsmentioning

confidence: 99%

Synthesis and study of luminescence properties of a deep red–emitting phosphor K₂LiAlF₆:Mn⁴⁺ for plant cultivation

Bawanthade,

Mistry,

Ugemuge

et al. 2023

Luminescence

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“…The PL intensity of the emission 6 P 7/2 → 6 S 7/2 of Gd 3+ in NaYF 4 : ( x %) Gd 3+ for various concentrations was computed to explore concentration quenching behaviour. The θ value in the following equation was calculated using a linear curve fitting [40]:

\log \frac{I}{x}=-\frac{\theta }{3}\log (x)+A.

…”

Section: Resultsmentioning

confidence: 99%

“…where I stands for the PL intensity of Gd 3+ at various concentra- (x%) Gd 3+ for various concentrations was computed to explore concentration quenching behaviour. The θ value in the following equation was calculated using a linear curve fitting [40]:…”

Section: Particle Size Analysismentioning

confidence: 99%

Synthesis and study of optical properties of a Gd³⁺‐doped NaYF₄ phosphor for phototherapy lamp application

Bawanthade,

Mistry,

Ugemuge

et al. 2024

Luminescence

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In recent trends, radiation falls under the narrowband ultraviolet‐B region (305–315 nm) widely used in phototherapy lamp applications in the treatment of skin diseases. In this paper, we report a Gd3+‐doped NaYF4 luminescent material synthesized for the first time using the low‐temperature co‐precipitation method. It crystallized into a face‐centred cubic structure, as confirmed by X‐ray diffraction characterization techniques and Rietveld refinement. The photoluminescence property of the as‐prepared sample shows a highly intense, sharp emission band obtained at 311 nm, which belongs to the narrowband ultraviolet‐B region and corresponds to the transition of the 6P7/2→8S7/2 level of the Gd3+ ions under 272 nm excitation (8S7/2 to 6IJ). The transitions of the Gd3+ ions are detected entirely with different concentrations of Gd3+ ions. Scanning electron microscopy analysis indicated that the average particle was 288 nm. The critical distance for energy transfer was calculated to be equal to 11.5017 Å. Dipole–dipole interaction is responsible for energy transfer, as analyzed by Dexter theory. These excellent optical characteristics, together with their highly efficient and low‐cost synthesis approach, indicate that synthesized NaYF4:Gd3+ phosphors have excessive potential for phototherapeutic lamp applications.

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“…White light-emitting diodes (w-LEDs) have substantially replaced conventional light sources (incandescent and fluorescent lamps) owing to their outstanding features such as low energy consumption, high brightness, high luminous efficiency, and long operational lifetimes . Rare earths (RE 3+ )-doped phosphors for w-LEDs have garnered considerable attention due to their widespread applications in the field of lighting. , Among many RE-doped phosphors, Tb 3+ doped metal oxides are well-known for obtaining green emission. − However, Tb 3+ -doped materials suffer from a lower luminescence due to the weak and narrow absorption cross-section (σ abs ∼ 10 –20 cm 2 ) originating from spin-forbidden electric dipole transitions between 4 f energy levels of Tb 3+ . , To overcome this issue, codoping of Tb 3+ ions with Ce 3+ sensitizers has attracted significant attention due to their high absorption cross-section (σ abs ∼ 10 –19 cm 2 ) in the UV region stemming from the allowed 4 f -5 d transition, shorter luminescence lifetime, and overlapping 5 d energy states of Ce 3+ ions with Tb 3+ 5 D J excited states. − For instance, GdPO 4 :Ce 3+ /Tb 3+ nanorods have been reported to be efficient hosts for the energy transfer from Ce 3+ to Tb 3+ ions with 28% quantum efficiency . The study revealed that the energy transfer depends upon the oxidation state of Ce ions in the host since dispersing codoped (GdPO 4 :Ce 3+ /Tb 3+ ) sample into KMnO 4 (oxidizing agent) solution resulted in significant luminescence quenching due to a change in the oxidation state of Ce from Ce 3+ to Ce 4+ .…”

Section: Introductionmentioning

confidence: 99%

Impact of Structural Changes on Energy Transfer in the Anion-Engineered Re³⁺:Y₂O₃ Through Low-Temperature Synthesis Approach

Jabrayilov,

Cohen,

Roman

et al. 2024

J. Phys. Chem. C

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Anion engineering has proven to be an effective strategy to tailor the physical and chemical properties of metal oxides by modifying their existing crystal structures. In this work, a low-temperature synthesis for rare earth (RE)-doped Y 2 O 2 SO 4 and Y 2 O 2 S was developed via annealing of Y(OH) 3 intermediates in the presence of elemental sulfur in a sealed tube, followed by a controlled reduction step. The crystal structure patterns (X-ray diffraction) and optical spectra (UV-IR) of Y 2 O 2 SO 4 , Y 2 O 2 S, and crystalline Y 2 O 3 were collected throughout the treatment steps to correlate the structural transformations (via thermogravimetric analysis) with the optical properties. Local and long-range crystallinities were characterized by using X-ray and optical spectroscopy approaches. Systematic shifts in the Eu 3+ excitation and emission peaks were observed as a function of SO 4 2− and S 2− concentrations resulting from a crystal evolution from cubic (Y 2 O 3 ) to trigonal (Y 2 O 2 S) and monoclinic (Y 2 O 2 SO 4 ), which can modify the local hybridization of sensitizer dopants (i.e., Ce 3+ ). Ultimately, Tb 3+ and Tb 3+ /Ce 3+ doping was employed in these hosts (Y 2 O 2 SO 4, Y 2 O 2 S, and Y 2 O 3 ) to understand energy transfer between sensitizer and activator ions, which showed significant enhancement for the monoclinic sulfate structure.

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Novel green emitting Tb3+ doped KCaF3 phosphor for WLEDs and TLD applications

Cited by 11 publications

References 38 publications

Synthesis and study of luminescence properties of a deep red–emitting phosphor K₂LiAlF₆:Mn⁴⁺ for plant cultivation

Synthesis and study of luminescence properties of a deep red–emitting phosphor K₂LiAlF₆:Mn⁴⁺ for plant cultivation

Synthesis and study of optical properties of a Gd³⁺‐doped NaYF₄ phosphor for phototherapy lamp application

Impact of Structural Changes on Energy Transfer in the Anion-Engineered Re³⁺:Y₂O₃ Through Low-Temperature Synthesis Approach

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Novel green emitting Tb3+ doped KCaF3 phosphor for WLEDs and TLD applications

Cited by 11 publications

References 38 publications

Synthesis and study of luminescence properties of a deep red–emitting phosphor K2LiAlF6:Mn4+ for plant cultivation

Synthesis and study of luminescence properties of a deep red–emitting phosphor K2LiAlF6:Mn4+ for plant cultivation

Synthesis and study of optical properties of a Gd3+‐doped NaYF4 phosphor for phototherapy lamp application

Impact of Structural Changes on Energy Transfer in the Anion-Engineered Re3+:Y2O3 Through Low-Temperature Synthesis Approach

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Synthesis and study of luminescence properties of a deep red–emitting phosphor K₂LiAlF₆:Mn⁴⁺ for plant cultivation

Synthesis and study of luminescence properties of a deep red–emitting phosphor K₂LiAlF₆:Mn⁴⁺ for plant cultivation

Synthesis and study of optical properties of a Gd³⁺‐doped NaYF₄ phosphor for phototherapy lamp application

Impact of Structural Changes on Energy Transfer in the Anion-Engineered Re³⁺:Y₂O₃ Through Low-Temperature Synthesis Approach