Morphology-controlled synthesis and luminescence properties of green-emitting NaGd(WO4)2:Tb3+ phosphors excited by n-UV excitation

Zhai, Yongqing; Sun, Qinglin; Yang, Shuai; Liu, Yaru; Wang, Jing; Ren, Shuxia; Ding, Shan

doi:10.1016/j.jallcom.2018.12.055

Cited by 24 publications

(9 citation statements)

References 33 publications

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“…6 As an alternative, near-ultraviolet (n-UV) LED (350−380 nm) chips coated with tricolor (blue, green, and red) phosphors to obtain white emission have been proposed. 7 In this scheme, n-UV W-LED devices are extremely dependent on the properties of the tricolor phosphors.…”

Section: ■ Introductionmentioning

confidence: 99%

Closing the Deep-Blue Gap: Realizing Narrow-Band Deep-Blue Emission with Strong n-UV Excitation by Cationic Substitution for Full-Spectrum Warm W-LED Lighting

Liu

Peng

Fu³

et al. 2022

ACS Sustainable Chem. Eng.

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Since the strong blue light from the conventional blue chip has negative effects on human health, near-ultraviolet (n-UV) white light-emitting diodes (W-LEDs) have been widely studied. However, the photoluminescence spectrum generated by tricolor (blue, green, and red) phosphors contains a notable cavity in the deep-blue region (400−430 nm), which reduces the color quality. In this work, we report a novel series of narrow-band deepblue-emitting phosphors with strong n-UV excitation, Ln 2 Si 2 O 7 :Bi 3+ (Ln = Gd, Y, Lu, Sc), and realize the tuning of emission from 422 to 403 nm via cationic substitution, which bridges the deep-blue gap. All of these phosphors are effectively excited by n-UV radiation at approximately 370 nm and exhibit narrow-band deep-blue emission with a full width at half-maximum (FWHM) < 50 nm. Among them, Sc 2 Si 2 O 7 :Bi 3+ generates 403 nm deep-blue emission with a 38 nm FWHM under 372 nm n-UV excitation, with high luminescence intensity and excellent thermal stability. Finally, 365 nm n-UV-pumped phosphor-converted (pc) W-LED devices are fabricated by combining Sc 2 Si 2 O 7 :Bi 3+ and commercially available phosphors, and they have a high colorrendering index (Ra) of 95.4 and a low correlated color temperature (CCT) of 3736 K. This result suggests that these phosphors have potential applications in full-spectrum warm white lighting.

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Section: ■ Introductionmentioning

confidence: 99%

Closing the Deep-Blue Gap: Realizing Narrow-Band Deep-Blue Emission with Strong n-UV Excitation by Cationic Substitution for Full-Spectrum Warm W-LED Lighting

Liu

Peng

Fu³

et al. 2022

ACS Sustainable Chem. Eng.

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“…In this study, CGW has a tetragonal scheelite structure. In the case of pH = 7, the growth of {001} crystal plane along the [001] crystal direction is faster than that of {101} crystal plane because of the larger surface‐free energy of {001} crystal plane, which results in the disappearance of {001} crystal plane and the formation of a spindle‐shaped grain surrounded by the exposed {101} plane 15,16 . However, when the pH value is increased to 8, there is likely to be an excess of WO 4 2− attached to the {001} crystal plane, which decreases the surface energy and hinders the growth of the {001} crystal plane, contributing to the appearance of tetragonal plate‐like particles.…”

Section: Resultsmentioning

confidence: 99%

Controllable hydrothermal synthesis and photoluminescence properties of CaGd₂(WO₄)₄:Eu³⁺ red‐emitting phosphor

Wang

Wei

et al. 2021

Int J Applied Ceramic Tech

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CaGd2(WO4)4:Eu3+ phosphors with controllable morphology were synthesized via the hydrothermal method. The influences of pH value, reaction time and Eu3+ concentration on the crystal structure, morphology, and photoluminescence properties of CaGd2(WO4)4:Eu3+ were studied. The pure tetragonal structure CaGd2(WO4)4 is obtained when the pH value is 8 and 9. Furthermore, by altering the pH value of the reaction solution, the morphologies of the CaGd2(WO4)4:Eu3+ phosphors evolve from spindle‐shaped grains to tetragonal plate‐like grains and finally to aggregated bulk particles. Under the 394 nm excitation, the phosphors display a bright red emission corresponding to the characteristic 4f‐4f transitions of Eu3+, and the intensity of emission peaks depends mainly on the pH value, the reaction time, and the Eu3+ concentration. The optimum photoluminescence performance is achieved for CaGd2‐x(WO4)4:xEu3+ (x = 1) phosphor synthesized at pH = 8 under the reaction time of 16 h. Finally, the thermal stability of the phosphors is analyzed at different ambient temperatures.

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“…n-UV-pumped WLEDs have the potential for indoor general lighting because of high CRI (>80) and low CCT (<4000 K). 2,[29][30][31][32][33][34] However, there is a cyan gap (480-500 nm) in the emission spectrum of WLEDs for common commercial combinations, which puts a limitation on their CRI values. 2,12,35,36 Hence, once bridge the so-called cyan gap, the CRI values could be further improved.…”

Section: Introductionmentioning

confidence: 99%

“…In order to overcome this weakness, another technology of manufactured WLED device has been widely proposed, which is based on the near‐ultraviolet (n‐UV, 380–420 nm) emitting LED chip combined with tricolor (red, green, and blue) emitting phosphors. n‐UV‐pumped WLEDs have the potential for indoor general lighting because of high CRI (>80) and low CCT (<4000 K) 2,29–34 . However, there is a cyan gap (480–500 nm) in the emission spectrum of WLEDs for common commercial combinations, which puts a limitation on their CRI values 2,12,35,36 .…”

Section: Introductionmentioning

confidence: 99%

A tunable blue–cyan dual emission phosphor in Ca₄₋_xLu₂_xHf₁₋_xGe₃O₁₂:Bi³⁺ via forming segregation structure for WLEDs

et al. 2022

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White light-emitting diodes (WLEDs) are always fabricated by a combination of the near-ultraviolet (n-UV)-emitting LED chip with tricolor emitting phosphors.However, improving the color rendering index (CRI) is limited due to the absence of cyan composition for common commercial combinations. Based on this, a series of blue-cyan dual-peaks emission Ca 4−x Lu 2x Hf 1−x Ge 3 O 12 (CLHGO):Bi 3+ phosphors with unique adjustability are developed by the solid solution design strategy. All the samples belong to the garnet structure with the Ia3d space group. Two relatively independent segregation structures [Ca 4 HfGe 3 O 12 ] and [Ca 3 Lu 2 Ge 3 O 12 ] are established in the samples. When Bi 3+ ions enter into the highly symmetrical hexagon coordination environment, a special phenomenon appears that the emission peaks consist of two stabilized narrowband emission bands at 435 and 475 nm, their intensity ratio could change continuously with the increase of solid solubility. All these results are confirmed by means of excitation and emission spectra, first principles calculation and decay curves. The Ca 3.4 Lu 1.2 Hf 0.4 Ge 3 O 12 :Bi 3+ sample, with a high efficiency around 84.1% and an excellent thermal stability (65.6%@150 • C), is chosen as the optimal sample to improve the blue and cyan compositions for full spectrum emission. Using the Ca 3.4 Lu 1.2 Hf 0.4 Ge 3 O 12 :Bi 3+ , commercial green (Ba, Sr) 2 SiO 4 :Eu 2+ phosphor, and commercial red CaAlSiN 3 :Eu 2+ phosphor on a 360-nm n-UV LED chip to fabricate WLED, which successfully bridge the cyan gap and the CRI value of the as-fabricated warm-white LED reaches 90.2. The previous results confirmed that CLHGO:Bi 3+ phosphors have promising application prospect in the development of n-UV-pumped warm-white LEDs with high-CRI values. The unique property performance originating from independent segregation structures provides more reference for the research on photoluminescence mechanism.

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Morphology-controlled synthesis and luminescence properties of green-emitting NaGd(WO4)2:Tb3+ phosphors excited by n-UV excitation

Cited by 24 publications

References 33 publications

Closing the Deep-Blue Gap: Realizing Narrow-Band Deep-Blue Emission with Strong n-UV Excitation by Cationic Substitution for Full-Spectrum Warm W-LED Lighting

Closing the Deep-Blue Gap: Realizing Narrow-Band Deep-Blue Emission with Strong n-UV Excitation by Cationic Substitution for Full-Spectrum Warm W-LED Lighting

Controllable hydrothermal synthesis and photoluminescence properties of CaGd₂(WO₄)₄:Eu³⁺ red‐emitting phosphor

A tunable blue–cyan dual emission phosphor in Ca₄₋_xLu₂_xHf₁₋_xGe₃O₁₂:Bi³⁺ via forming segregation structure for WLEDs

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Morphology-controlled synthesis and luminescence properties of green-emitting NaGd(WO4)2:Tb3+ phosphors excited by n-UV excitation

Cited by 24 publications

References 33 publications

Closing the Deep-Blue Gap: Realizing Narrow-Band Deep-Blue Emission with Strong n-UV Excitation by Cationic Substitution for Full-Spectrum Warm W-LED Lighting

Closing the Deep-Blue Gap: Realizing Narrow-Band Deep-Blue Emission with Strong n-UV Excitation by Cationic Substitution for Full-Spectrum Warm W-LED Lighting

Controllable hydrothermal synthesis and photoluminescence properties of CaGd2(WO4)4:Eu3+ red‐emitting phosphor

A tunable blue–cyan dual emission phosphor in Ca4−xLu2xHf1−xGe3O12:Bi3+ via forming segregation structure for WLEDs

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Product

Resources

About

Controllable hydrothermal synthesis and photoluminescence properties of CaGd₂(WO₄)₄:Eu³⁺ red‐emitting phosphor

A tunable blue–cyan dual emission phosphor in Ca₄₋_xLu₂_xHf₁₋_xGe₃O₁₂:Bi³⁺ via forming segregation structure for WLEDs