JOURNAL OF RARE EARTHS
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2024
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IF 5.2
Sihan Yang,Xuyan Xue,Feng Jiang,Liang Dong,Qi Zhu,Xuejiao Wang,Ji-Guang Li
The emission wavelength of current near-infrared phosphors activated by Cr 3+ is generally smaller than 900 nm in near-infrared (NIR) I region, and it is extremely challenging and is of great practical significance to realize emission towards NIR-II region. In this study, a novel Cr 3+ excited KSrScSi 2 O 7 silicate broad-band phosphor was prepared using the traditional solid-state method. Cr 3+ resides in a weak crystal field in the KSrScSi 2 O 7 lattice and exhibits broad-band near-infrared emission at 984 nm, longer than those of most Cr 3+ activated phosphors, under 493 nm blue light excitation. This is due to the strong charge polarization caused by the unique local coordination environment of the silicate matrix, which leads to a reduction in the crystal field splitting energy of the [ScO 6 ] octahedron where Cr 3+ is located and the downward shift of the 4 T 2 energy level. The optimal doping concentration of Cr 3+ is found to be 2 mol%, and the quenching mechanism is dipole-dipole interaction. Compared to the phosphors with similar emission wavelengths ( λ em > 900 nm), KSrScSi 2 O 7 :Cr 3+ demonstrates outstanding advantages in various aspects of luminescent performance. The fabricated phosphor-converted light-emitting diode (pc-LED) is shown to have the potential for night vision and non-invasive imaging. Novel application of KSrScSi 2 O 7 : x Cr 3+ as stable green ceramic pigments is also explored. The KSrScSi 2 O 7 : x Cr 3+ powders show a bright yellowish green appearance, and the KSrScSi 2 O 7 :0.02Cr 3+ typical composition has chromaticity values of L* = 82.73, a* = –8.53, b* = 7.97. Remarkably, the glazing samples using KSrScSi 2 O 7 : x Cr 3+ as pigments well retain the bright color after 1200 °C sintering in different atmospheres. Therefore, multi-functional applications of KSrScSi 2 O 7 : x Cr 3+ for near-infrared spectroscopy and as ceramic pigments are achieved in this work.
研究领域:
材料科学
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光学
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陶瓷科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Materials Au
·
2022
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IF 0
Shunqi Lai,Ming Zhao,Yifei Zhao,Maxim S. Molokeev,Zhiguo Xia
Regulation of Eu2+ dopants in different cation sites of solid-state materials is of great significance for designing multicolor phosphors for light-emitting diodes (LEDs). Herein, we report the selective occupation of Eu2+ for multiple cationic sites in KSrScSi2O7, and the tunable photoluminescence from blue to cyan is realized through Eu2+ doping concentration-dependent crystal-site engineering. Eu2+ preferably occupies the K and Sr sites in KSrScSi2O7 at a low doping concentration, resulting in a 440 nm blue emission. As the Eu2+ concentration increases, a new Eu2+ substitution pathway is triggered, that is, Eu2+ enters the Sc site, leading to the red-shifted emission spectra from 440 to 485 nm. The doping mechanism and photoluminescence properties are corroborated by structural analysis, optical spectroscopy study, and density functional theory calculations. The optical properties of the as-fabricated white LEDs are studied, which demonstrates that these phosphors can be applied to full-spectrum phosphor-converted LEDs. This study provides a new design strategy to guide the development of multicolor Eu2+-doped oxide phosphors for lighting applications.
研究领域:
材料科学
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光学
✓ 已验证
DOI
CERAMICS INTERNATIONAL
·
2025
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IF 5.6
Liang Dong,Sihan Yang,Jian He,Qi Zhu,Ji-Guang Li,Xuejiao Wang
This work studied the Pr 3+ single doped KSrScSi 2 O 7 : x Pr 3+ ( x = 0–10 at%) and Ce 3+ -Pr 3+ codoped KSrScSi 2 O 7 : Ce 3+ , y Pr 3+ ( y = 0.5–7 at%) phosphors, including photoluminescence characteristics, crystal structure, and the mechanism of Ce 3+ → Pr 3+ energy transfer. All the samples were synthesized by the high-temperature solid-phase method. Under 448 nm light excitation, the KSrScSi 2 O 7 : x Pr 3+ ( x = 0.5–10 at%) phosphors emitted narrow-band cyan-blue light (490 nm, 3 P 0 → 3 H 4 ), green light (530 nm, 3 P 1 → 3 H 5 ), orange-red light (605 nm, 1 D 2 → 3 H 4 and 3 P 0 → 3 H 6 ), and red light (645 nm, 3 P 0 → 3 F 2 ). The KSrScSi 2 O 7 : 3 at%Ce 3+ , y Pr 3+ ( y = 1–7 at%) phosphors exhibited broad-band (380–550 nm) luminescence of Ce 3+ and narrow-band luminescence of Pr 3+ under 365 nm light excitation. In comparison with KSrScSi 2 O 7 : 3 at% Ce 3+ , the doping of 3 at% Pr 3+ beneficially enhanced the thermal stability of the phosphor (I 423 K /I 298 K from 37.4 % to 48.6 %), which was attributed to the introduction of electron trap by Pr 3+ . Through trapping energy levels compensation, the thermal stability of the phosphor was improved. By measuring the fluorescence decay kinetics of Ce 3+ in KSrScSi 2 O 7 : 3 at% Ce 3+ , y Pr 3+ ( y = 0–7 at%), we have proved the existence of Ce 3+ → Pr 3+ energy transfer, whose efficiency rises from 42.8 % to 67.2 % along with increasing Pr 3+ concentration. A pc-WLED was fabricated by combining KSrScSi 2 O 7 : 3 at% Ce 3+ , 3 at% Pr 3+ with commercial red and green phosphors, and the device showed a high color rendering index (CRI = 94.8) and superior color rendering stability.
✓ 已验证
产品关联
DOI
高影响因子
OPTICAL MATERIALS
·
2025
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IF 4.2
Liang Dong,Ziying Wang,Sihan Yang,Qi Zhu,Ji-Guang Li,Xuejiao Wang
Phosphor-converted white light-emitting diode (pc-WLED) is crucial for solid-state lighting, but the color rendering index of commercial pc-WLED needs to be improved. In this study, a series of silicates KSrScSi 2 O 7 : x Ce 3+ ( x= 0-10at%) were synthesized. Under the 365 nm near-ultraviolet excitation, the silicate emits a high-quality broadband cyan-blue light (385-550 nm) covering the cyan gap. The emission intensity reaches its maximum at approximately 450 nm and the emission peak is slightly shifted with varying Ce 3+ concentration, which is because Ce 3+ doping changes the crystal field around the luminescence center. The prepared phosphors showed promising properties for application in high-color rendering lighting. The crystal structure analysis via X-ray diffraction and Rietveld refinement and Gaussian fitting of the PL spectra indicated that Ce 3+ occupies the Sr 2+ and K + positions in the monoclinic host lattice. The optimal Ce 3+ content is 3at% and concentration quenching is attributed to the non-radiative energy transfer between the nearest-neighboring Ce 3+ ions. The temperature-dependent luminescence showed that the T 50 is 394 K for the KSrScSi 2 O 7 : x Ce 3+ materials. The thermal quenching is attributed to increased lattice vibrations and enhanced non-radiative transitions at elevated temperatures. The performance of the pc-WLED device fabricated with KSrScSi 2 O 7 : 3at%Ce 3+ was studied, and the device showed a high-color rendering index (Ra=93.8) and exceptional stability during operation.
研究领域:
材料科学
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光学工程
✓ 已验证
产品关联
DOI
高影响因子
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