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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yun, Xiangyan, Zhou, Jun, Zhu, Yaohui, Molokeev M. S., Jia, Yetong, Wei, Chao, Xu, Denghui, Sun, Jiayue
Заглавие : Thermometry and up-conversion luminescence of Ln3+ (Ln = Er, Ho, Tm)-doped double molybdate LiYbMo2O8
Место публикации : J. Mater. Sci.: Mater. Electron. - 2020. - Vol. 31, Is. 21. - P.18370-18380. - ISSN 0957-4522, DOI 10.1007/s10854-020-04382-8. - ISSN 1573-482X(eISSN)
Примечания : Cited References: 41. - This work is supported by the National Natural Science Foundation of China (No. 21576002 and 61705003) and Beijing Technology and Business University Research Team Construction Project (No. PXM2019_014213_000007)
Предметные рубрики: TEMPERATURE SENSING BEHAVIOR
OPTICAL THERMOMETRY
EMISSION
PHOSPHOR
Аннотация: The discovery of stable and highly sensitive up-conversion (UC) phosphors using the fluorescence intensity ratio (FIR) is a significant challenge in the field of optical temperature sensor. Er3+/Ho3+/Tm3+-doped LiYbMo2O8 UC phosphors with excellent luminescence properties were successfully synthesized through a high-temperature solid-state reaction, and the crystal structure and UC luminescence properties were discussed in detail. The UC process has been investigated by spectra pump power dependence and further explained via the energy level diagram. All emission processes about Er3+ ions and Ho3+ ions are two-photon processes and the blue emission process about Tm3+ ions is a combination of two-photon process and three-photon process. Thermal sensing performances depended on FIR technology were estimated and the sensitivities of LiYb1−xMo2O8:xLn3+ included absolute sensitivity (Sa) and relative sensitivity (Sr) can produce particular change rules with the temperature, which can serve as excellent candidates for applications in optical temperature sensing. With the increase of temperature, the maximum values of Sr of LiYb1−xMo2O8:xLn3+ are 1.16% K−1 (0.05Er3+), 0.25% K−1 (0.01Ho3+), and 0.51% K−1 (0.01Tm3+), respectively. In addition, the Sa value of LiYb0.95Mo2O8:0.05Er3+ phosphor will reach the maximum (1.08% K−1) at 475 K, while the maximum values of Sa of LiYb0.99Mo2O8:0.01Ho3+ and LiYb0.99Mo2O8:0.01Tm3+ are 0.16% K−1, 0.14% K−1.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou J., Chen Y., Jiang C., Milicevic B., Molokeev M. S., Brik M. G., Bobrikov I. A., Yan J., Li J., Wu M.
Заглавие : High moisture resistance of an efficient Mn4+-activated red phosphor Cs2NbOF5:Mn4+ for WLEDs
Место публикации : Chem. Eng. J. - 2021. - Vol. 405. - Ст.126678. - ISSN 13858947 (ISSN), DOI 10.1016/j.cej.2020.126678
Примечания : Cited References: 43. - This work was financially supported by grants from the National Natural Science Foundation of China (No. 51802359, 21801254, 51902354) and its Joint Funds of Yunnan and Guangdong Province (No. U1702254 and No. U1801253), Special Fund of Guangdong Province Project for Applied Science and Technology Research and Development (No. 2017B090917001), Guangdong Basic and Applied Basic Research Foundation (No. 2020A1515010556), the Fundamental Research Funds for the Central Universities (No. 19lgpy123), and China Postdoctoral Science Foundation (No. 2019M663230). M. G. Brik thanks the supports from the National Recruitment Program of High-end Foreign Experts (No. GDT20185200479 and GDW20145200225), the Programme for the Foreign Experts (No. W2017011) and Wenfeng High-end Talents Project (No. W2016-01) offered by Chongqing University of Posts and Telecommunications (CQUPT) , Estonian Research Council grant PUT PRG111, and European Regional Development Fund (TK141)
Аннотация: Mn4+-activated fluoride red phosphors, the most important red phosphors for warm white light emitting diodes (LEDs), usually suffer from inherent poor moisture resistance which is a major obstacle to their long-lasting outdoor applications in a high humidity environment. Surface modification of phosphors by coating with either organic or inorganic shells is an effective way to improve waterproof stability. However, the coating procedure usually has a negative impact on the luminous efficacy due to the increased passivation shell thickness. In this work, Mn4+-activated oxyfluoroniobate (Cs2NbOF5), a highly efficient phosphor with internal quantum efficiency of ca. 82%, has been successfully synthesized and it is interesting to note that Cs2NbOF5:Mn4+ can exhibit remarkably improved waterproof stability even without surface coating compared to well-accepted commercial fluoride red-emitting phosphor, K2SiF6:Mn4+. The results obtained indicate that Nb5+ ions inside red phosphor play a crucial role in improving the water-resistant performance of Mn4+, which provides a new concept for overcoming the downside of their waterproof in humid conditions and maintaining the luminescence efficiency. In the final phase white LEDs with a high luminous efficacy of 174 lm/W (higher than commercial fluoride red phosphors), low correlated color temperature (3164 K) and high color rendering index (Ra = 90 and R9 = 85) have been fabricated using Cs2NbOF5:Mn4+.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu, Gaochao, Molokeev M. S., Lei, Bingfu, Xia, Zhiguo
Заглавие : Two-site Cr3+ occupation in the MgTa2O6:Cr3+ phosphor toward broad-band near-infrared emission for vessel visualization
Место публикации : J. Mater. Chem. C. - 2020. - Vol. 8, Is. 27. - P.9322-9328. - ISSN 2050-7526, DOI 10.1039/d0tc01951h. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 52. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51972118, 51961145101 and 51722202), Fundamental Research Funds for the Central Universities (D2190980), the Guangzhou Science & Technology Project (202007020005), the Guangdong Provincial Science & Technology Project (No. 2018A050506004), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). This work is also funded by RFBR according to the research project No. 19-52-80003.
Предметные рубрики: LIGHT-SOURCES
PHOSPHOR
LUMINESCENCE
PHOTOLUMINESCENCE
Аннотация: Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have great potential in photonic, optoelectronic and biological applications, while the discovery of a broad-band NIR phosphor still remains a challenge. Here, we report a novel Cr3+-activated MgTa2O6 phosphor with an asymmetrical emission band ranging from 700 to 1150 nm and a large full width at half maximum (FWHM) of 140 nm upon 460 nm blue light excitation. The broad spectrum is assigned to the overlap of two bands centered at 910 and 834 nm, which originate from the spin-allowed transition of 4T2 → 4A2 for different Cr3+ ions located in the two six-coordinated crystallographic sites of Mg2+ and Ta5+, respectively. The distribution of blood vessels and bones in human palm and wrist is observed with the assistance of a commercial NIR camera and a fabricated pc-LED, which demonstrates that the MgTa2O6:Cr3+ phosphor is promising in biological applications.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gai S., Zhu H., Gao P., Zhou C., Kong Z., Molokeev M. S., Qi Z., Zhou Z., Xia M.
Заглавие : Structure analysis, tuning photoluminescence and enhancing thermal stability on Mn4+-doped La2-xYxMgTiO6 red phosphor for agricultural lighting
Место публикации : Ceram. Int. - 2020. - Vol. 46, Is. 12. - P.20173-20182. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.05.095
Примечания : Cited References: 40. - The authors would like to gratefully acknowledge funds from the National Natural Science Foundation of China (Grant No. 21706060 , 51703061 , 51974123 ), the Hunan Graduate Research and Innovation Project (Grant No. CX2018B396 ), the Hunan provincial Engineering Technology Research Center for Optical Agriculture (Grant No. 2018TP2003 ), the Scientific Research Fund of Hunan Provincial Education Department (15K058, 19C0903), the Natural Sciences Foundation of Hunan agricultural university, China (Grant No. 19QN11), the Science and Technology project of Changsha (KH1801219) and the Huxiang high level talent gathering project (2019RS1077)
Аннотация: Currently, phosphor-converted LEDs (pc-LEDs) are revolutionizing the industry of plant growth lighting. To meet the requirements of this technology, phosphors with tunable photoluminescence, high thermal stability and luminous intensity are required. Herein, we found that the simple substitution of yttrium for lanthanum in La2MgTiO6:Mn4+ (LMT:Mn4+) system could satisfy above three criteria simultaneously. The photoluminescence properties can be regulated by continuously controlling the chemical composition of La2-xYxMgTiO6:Mn4+ solid solution. The La sites are occupied by Y ions, causing a significant blue shift in the emission spectra which owing to the change of local crystal field strengthen. Meanwhile, the thermal stability and decay lifetimes are also varied due to the variation of local structure and band gap energy. The thermal stability of the material reaches 83.5% at 150 °C, which is better than the reported La2MgTiO6:Mn4+ and Y2MgTiO6:Mn4+ phosphors. The electronic luminescence (EL) of pc-LED devices using La2-xYxMgTiO6:Mn4+ red phosphor is evaluated, which matching the absorption regions of plant pigments well, reflecting the superiority of the studied phosphors in plant growth lighting areas.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xie F., Xu D., Wu Z., Molokeev M. S., Milicevic B., Li H., Shi J.
Заглавие : Improving thermal stability of novel single-component white-light emitting phosphor Ca8MgLu(PO4)7:Tm3+, Dy3+ by back-energy-transfer
Место публикации : J. Lumines. - 2020. - Vol. 227. - Ст.117516. - ISSN 00222313 (ISSN), DOI 10.1016/j.jlumin.2020.117516
Примечания : Cited References: 54. - This work was financially supported by grants from the National Natural Science Foundation of China (No. 21771195 and 51972347), the Natural Science Foundation of Guangdong Province (No. 2016A030313118), the Science and Technology program of Huizhou City (No. 2016X0421036), the Department of Education of Guangdong Province (No. 2018KQNCX249), and the Professorial and Doctoral Scientific Research Foundation of Huizhou University (No. 2018JB012)
Аннотация: The light degradation of WLED devices after long-time use has been proved to be mainly caused by thermal quenching of phosphors, therefore, the design of single-component white-light emitting phosphors with high thermal stability remains a huge challenge. A novel single-phase white light-emitting phosphor Ca8MgLu(PO4)7:Tm3+,Dy3+ was designed and prepared in this work. The photoluminescent results show that white light emission from the phosphor can be achieved by controlling the ratio of Tm3+ and Dy3+ to adjust the relative intensity of the emission at 451 nm of Tm3+ and the emissions at 488, 571 and 660 nm of Dy3+. The luminescence decay results reveal that there is energy transfer from Tm3+ to Dy3+ in Ca8MgLu(PO4)7:Tm3+,Dy3+ and the efficiency of energy transfer between the two dopants reaches as much as 55%. Temperature-dependent luminescent analyses suggest the highly stable emission of Ca8MgLu0.76(PO4)7:0.12Tm3+,0.12Dy3+ as the integrated emission intensity of the phosphor at 475 K reduces only about 13% of that at room temperature, which is due to the back-energy-transfer from highly doped Dy3+ to Tm3+ that compensates the luminescence energy. This single-phase white-light emitting phosphor exhibits superior color and luminescence stability and thus may find a potential application in WLEDs.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu, Dongjie, Yun, Xiaohan, Li, Guogang, Dang, Peipei, Molokeev M. S., Lian, Hongzhou, Shang, Mengmeng, Lin, Jun
Заглавие : Enhanced cyan emission and optical tuning of Ca3Ga4O9:Bi3+ for high-quality full-spectrum white light-emitting diodes
Место публикации : Adv. Opt. Mater. - 2020. - Vol. 8, Is. 22. - Ст.2001037. - ISSN 2195-1071, DOI 10.1002/adom.202001037
Примечания : Cited References: 55. - This work was financially supported by the National Natural Science Foundation of China (NSFC No. 51932009, 51720105015, 51672265, 51672266, 51672257 and 51672259), the Key Research Program of Frontier Sciences, CAS (Grant No. YZDY-SSW-JSC018), Science and Technology Cooperation Project between Chinese and Australian Governments (2017YFE0132300), the Jiangmen Innovative Research Team Program (2017), and the Major Program of Basic Research and Applied Research of Guangdong Province (2017KZDXM083)
Предметные рубрики: ENERGY-TRANSFER
TUNABLE LUMINESCENCE
PHOSPHOR
CRYSTAL
MODULATION
Аннотация: Highly efficient cyan‐emitting phosphor materials are indispensable for closing the cyan gap in spectra of the traditional phosphor‐converted white light‐emitting diodes (WLEDs) to achieve high‐quality full‐spectrum white lighting. In this work, bright cyan‐emitting Ca3Ga4O9 (CGO):0.02Bi3+,0.07Zn2+ phosphor is developed to bridge the cyan gap. Such a Bi3+,Zn2+ codoping enhances the cyan emission of CGO:0.02Bi3+ by 4.1 times due to the influence of morphology and size of phosphor particles, charge compensation and lattice distortion. Interestingly, codoping La3+ ions into the current system can achieve a photoluminescence tuning of CGO:0.02Bi3+ from cyan to yellowish‐green by crystallographic site engineering. Besides, Bi3+–Eu3+ energy transfer is successfully realized in CGO:0.02Bi3+,0.07Zn2+,nEu3+ phosphors and the emission color tuning from cyan to orange is observed. The investigation of thermal quenching behaviors reveals that the incorporation of Zn2+ and La3+ improves the thermal stability of CGO:0.02Bi3+. Finally, CGO:0.02Bi3+,0.07Zn2+,0.10Eu3+ phosphor is employed to obtain a single‐phased warm WLED device. A full‐spectrum WLED device with remarkable color rendering index (Ra) of 97.4 and high luminous efficiency of 69.72 lm W−1 is generated by utilizing CGO:0.02Bi3+,0.07Zn2+ phosphor. This result suggests the important effect of CGO:0.02Bi3+,0.07Zn2+ phosphor on closing the cyan gap, providing new insights of cyan‐emitting phosphors applied in full‐spectrum white lighting.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang, Qiuhong, Li, Junhao, Jiang, Wei, Lin, Litian, Ding, Jianhong, Brik, Mikhail G., Molokeev M. S., Ni, Haiyong, Wu, Mingmei
Заглавие : CaY2Al4SiO12:Ce3+,Mn2+: a single component phosphor to produce high color rendering index WLEDs with a blue chip
Место публикации : J. Mater. Chem. C. - 2021. - Vol. 9, Is. 34. - P.11292-11298. - ISSN 2050-7526, DOI 10.1039/d1tc01770e. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 35. - This work has been financially supported by the National Nature Science Foundation of China (51902063, 51902354, U1801253), the Science and Technology Project of Guangdong Province (2018A050506061), the Science and Technology Project of Guangzhou City (202007020005, 202007020008) and GDAS' Project of Science and Technology Development (2020GDASYL-20200302010, 2018GDASCX-0110). M. G. Brik also thanks the support from the Chongqing Recruitment Program for 100 Overseas Innovative Talents (Grant No. 2015013), the Program for the Foreign Experts (Grant No. W2017011) and Wenfeng High-End Talents Project (Grant No. W2016-01) offered by Chongqing University of Posts and Telecommunications (CQUPT), Estonian Research Council grant PUT PRG111, European Regional Development Fund (TK141) and NCN project 2018/31/B/ST4/00924
Предметные рубрики: GARNET PHOSPHOR
ENERGY-TRANSFER
RED EMISSION
LUMINESCENCE PROPERTIES
Аннотация: A high color rendering index white light emitting diode (WLED) is generally produced by combining yellow and red mixed phosphors on a blue chip. Herein we report a single component phosphor based on CaY2Al4SiO12 (CYAS) to achieve warm white light emission with a high color rendering index (Ra), which can be up to 90.5. Ce3+, Mn2+ singly doped and co-doped CYAS phosphors have been synthesized by solid state reactions, respectively, for comparative investigations. The Rietveld X-ray diffraction (XRD) refinements show that the CYAS host crystallizes in a cubic structure with the Ia[3 with combining macron]d space group. The valence states of Ce and Mn inside the CYAS host have been confirmed by XPS and EPR. Ce3+ occupies the Ca2+/Y3+ site and generates a yellow emission band around 543 nm from its characteristic 5d–4f transition. Mn2+ occupies both the dodecahedron Ca2+/Y3+ and octahedral Al3+ sites, emitting red and deep red lights at 616 nm and 750 nm, respectively. These two emission bands are attributed to the 4T1(4G)–6A1(6S) transitions of Mn2+. Upon 460 nm light excitation, both the Ce3+ and Mn2+ characteristic emissions can be obtained, in which the emissions of Mn2+ result from the occurrence of energy transfer from Ce3+ in CYAS. All the results indicate that the prepared CYAS:Ce3+,Mn2+ could be a promising single component phosphor for blue chip WLEDs.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zou X., Wang X., Zhang H., Kang Y., Yang X., Zhang X., Molokeev M. S., Lei B.
Заглавие : A highly efficient and suitable spectral profile Cr3+-doped garnet near-infrared emitting phosphor for regulating photomorphogenesis of plants
Место публикации : Chem. Eng. J. - 2022. - Vol. 428. - Ст.132003. - ISSN 13858947 (ISSN), DOI 10.1016/j.cej.2021.132003
Примечания : Cited References: 46. - The work was supported from the National Natural Science Foundations of China (Nos. 21671070, 51802101), the Guangdong Basic and Applied Basic Research Foundation (No. 2021A1515012613), the Guangdong Provincial Science & Technology Project (Nos. 2020A1414010046, 2021A0505050006), the Guangzhou Science & Technology Project (No. 202007020005), the Natural Science Foundation of Guangdong Province (No. 2018A030310217), the Project of GDUPS (2018) for Prof. Bingfu LEI, and the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (Nos. 2021KJ131 , 2021KJ122)
Аннотация: Far-red/phytochrome (PFR) plays a key role in photomorphogenesis of plants. However, how to obtain a near-infrared (NIR) emitting phosphor with high external quantum efficiency (EQE), suitable spectral profile, and low thermal quenching remains a huge challenge. Herein, a NIR phosphor, Gd2.4Lu0.6Ga4AlO12:Cr3+,H3BO3 (GLGA:Cr3+) was developed via regulating the crystal field environment and adding fluxes, which exhibits a peak maximum at 728 nm with a relatively narrow full-width at half maximum (FWHM) of 107 nm, matching well with the absorption band of PFR. Upon 450 nm excitation, the internal quantum efficiency (IQE) and EQE of the optimal phosphor are 90.3% and 32.0%, respectively. At 423 K, the integrated emission intensity of the investigated phosphor is about 75% of that at room temperature. Benefiting from the excellent optical performance, a NIR phosphor-converted light-emitting diode (pc-LED) was fabricated, which shows a NIR output power of 505.99 mW and photoelectric conversion efficiency of 11.24% at 300 mA. Moreover, plant growth experiments demonstrate that the biomass of pea seedlings is increased by 67.72% under supplementary NIR light irradiation. The findings of this research will motivate further research on new Cr3+-doped NIR phosphors for regulating photomorphogenesis of plants.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lai S., Hu T., Molokeev M. S., Xia Z.
Заглавие : Photoluminescence tuning in Ba3ScB3O9:Eu2+ phosphor by crystal-site engineering
Место публикации : Phys. Open. - 2021. - Vol. 8. - Ст.100077. - ISSN 26660326 (ISSN), DOI 10.1016/j.physo.2021.100077
Примечания : Cited References: 31. - The present work was supported by the National Natural Science Foundation of China (Grant Nos. 51972118 and 51961145101), International Cooperation Project of National Key Research and Development Program of China (2021YFE0105700), the Guangzhou Science & Technology Project (202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). This work is also funded by RFBR according to the research project No. 19-52-80003
Аннотация: Controlled photoluminescence tuning is essential for optimizing and accelerating the application of phosphor materials. Here, we adopt the crystal-site engineering method to tailor the photoluminescence properties in Ba3ScB3O9:Eu2+. Ba3ScB3O9 host contains multiple cationic sites which help to finely regulate Eu2+ site occupancies and thus the emission color. The relationship between Eu2+ emission and the local environments has been analyzed, and we demonstrate that the emission colors of the phosphors can be widely tuned from NIR to yellow by chemically driving the Eu2+ from octahedrally-coordinated Sc3+ sites to nine-fold coordinated Ba2+ sites. Our study will initiate and guide more explorations on discovering new phosphors through crystal-site engineering.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hu, Tao, Gao, Yan, Molokeev M. S., Xia, Zhiguo, Zhang, Qinyuan
Заглавие : Eu2+ stabilized at octahedrally coordinated Ln3+ site enabling red emission in Sr3LnAl2O7.5 (Ln = Y or Lu) phosphors
Место публикации : Adv. Opt. Mater. - 2021. - Vol. 9, Is. 9. - Ст.2100077. - ISSN 2195-1071, DOI 10.1002/adom.202100077
Примечания : Cited References: 25. - The work was supported from the National Natural Science Foundations of China (Grant Nos. 51972118, 51961145101, and 51722202), the Fundamental Research Funds for the Central Universities (D2190980), the Guangzhou Science & Technology Project (202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01x137), and RFBR according to the research project (19-52-80003)
Аннотация: Red spectrum loss in phosphor-converted light-emitting diodes (pc-LEDs) restricts high-quality warm-white lighting. Herein, two blue-light excitable red-emitting Sr3LnAl2O7.5:Eu (Ln = Y or Lu) phosphors are reported, and red emission originating from an unprecedented substitution model, with Eu2+ occupied sixfold octahedrally coordinated lanthanide (Ln3+) sites is demonstrated. Site occupancy identification reveals that three different sites are occupied by Eu2+ and one distinct site is occupied by Eu3+, and the Eu2+ stabilized at Ln3+ site accompanied by Eu3+ selectively occupies at Sr2+ site as a charge compensator. An anomalous prolonged Eu2+-photoluminescence decay emission with increasing temperature in the low-temperature region is demonstrated. This accounts for the trapped electrons, which are thermally released from shallow traps and eventually populate the Eu2+ 5d level to form an excited-state Eu2+. The findings help better understand Eu2+ occupancy and luminescence. These also provide a new perspective for the exploration of novel Eu2+ activated oxide-based red phosphor for pc-LEDs.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hu T., Ning L., Gao Y., Qiao J., Song E., Chen Z., Zhou Y., Wang J., Molokeev M. S., Ke X., Xia Z., Zhang Q.
Заглавие : Glass crystallization making red phosphor for high-power warm white lighting
Место публикации : Light Sci. Appl. - 2021. - Vol. 10, Is. 1. - Ст.56. - ISSN 20955545 (ISSN), DOI 10.1038/s41377-021-00498-6
Примечания : Cited References: 50. - The present work was supported by the National Natural Science Foundations of China (Grant Nos. 51972118, 51961145101, 51722202 and 11974022), the Guangzhou Science & Technology Project (202007020005), the Fundamental Research Funds for the Central Universities (D2190980), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137)
Аннотация: Rapid development of solid-state lighting technology requires new materials with highly efficient and stable luminescence, and especially relies on blue light pumped red phosphors for improved light quality. Herein, we discovered an unprecedented red-emitting Mg2Al4Si5O18:Eu2+ composite phosphor (λex = 450 nm, λem = 620 nm) via the crystallization of MgO–Al2O3–SiO2 aluminosilicate glass. Combined experimental measurement and first-principles calculations verify that Eu2+ dopants insert at the vacant channel of Mg2Al4Si5O18 crystal with six-fold coordination responsible for the peculiar red emission. Importantly, the resulting phosphor exhibits high internal/external quantum efficiency of 94.5/70.6%, and stable emission against thermal quenching, which reaches industry production. The maximum luminous flux and luminous efficiency of the constructed laser driven red emitting device reaches as high as 274 lm and 54 lm W−1, respectively. The combinations of extraordinary optical properties coupled with economically favorable and innovative preparation method indicate, that the Mg2Al4Si5O18:Eu2+ composite phosphor will provide a significant step towards the development of high-power solid-state lighting.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yang X., Chen W., Wang D., Chai X., Xie G., Xia Z., Molokeev M. S., Liu Y., Lei B.
Заглавие : Near-infrared photoluminescence and phosphorescence properties of Cr3+-Doped garnet-type Y3Sc2Ga3O12
Место публикации : J. Lumin. - 2020. - Vol. 225. - Ст.117392. - ISSN 00222313 (ISSN), DOI 10.1016/j.jlumin.2020.117392
Примечания : Cited References: 26. - The present work was supported by the National Natural Science Foundations of China (Grant No. 21671070); the Project of GDUPS (2018) for Prof. Bingfu LEI; the Guangzhou Science & Technology Project, China (No. 201704030086); and the National Undergraduate Innovation and Entrepreneurship Training Program granted for Gening Xie (No. 201910564035)
Аннотация: Garnet-type Y3Sc2Ga3O12:Cr3+ phosphor has been synthesized by a solid-state reaction. XRD result revealed the successful phase formation and Cr3+ doping in Y3Sc2Ga3O12. The excitation spectrum at about 260, 450, and 630 nm corresponded to three spin-allowed Cr3+ d-d intra-transitions of 4A2-4T1 (4P), 4A2-4T1 (4F), and 4A2-4T2 (4F), respectively, among which the near infrared (NIR) emission peak at around 740 nm is identified. Moreover, the phosphorescence emission property, thermoluminescence and related luminescence mechanisms are discussed as well. The fabricated NIR phosphor-converted light-emitting diodes (pc-LEDs) suggest its potential of Y3Sc2Ga3O12:Cr3+ phosphor for non-visible light source application.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Qiao, Jianwei, Ning, Lixin, Molokeev M. S., Chuang, Yu-Chun, Zhang, Qinyuan, Poeppelmeier, Kenneth R., Xia, Zhiguo
Заглавие : Site-Selective Occupancy of Eu2+ Toward Blue-Light-Excited Red Emission in a Rb3YSi2O7:Eu Phosphor
Место публикации : Angew. Chem. - 2019. - Vol. 131, Is. 33. - P.11645-11650. - ISSN 1521-3757, DOI 10.1002/ange.201905787
Примечания : Cited References: 41. - This work is supported by the National Natural Science Foundation of China (51722202, 51572023, and 11574003), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF-TP-18-002C1), and the Guangdong Provincial Science & Technology Project (2018A050506004). K.R.P. recognizes that this work was made possible by support from the National Science Foundation, Solid State Materials Chemistry award DMR-1608218.
Предметные рубрики: LUMINESCENCE PROPERTIES
CE3+
ENERGY
PHOTOLUMINESCENCE
TRANSITION
Аннотация: Establishing an effective design principle in solid-state materials for a blue-light-excited Eu2+-doped red-emitting oxide-based phosphors remains one of the significant challenges for white light-emitting diodes (WLEDs). Selective occupation of Eu2+ in inorganic polyhedra with small coordination numbers results in broad-band red emission as a result of enhanced crystal-field splitting of 5d levels. Rb3YSi2O7:Eu exhibits a broad emission band at λmax=622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu2+ ions preferably occupy RbO6 and YO6 polyhedra and show the characteristic red emission band of Eu2+. The excellent thermal quenching resistance, high color-rendering index Ra (93), and low CCT (4013 K) of the WLEDs clearly demonstrate that site engineering of rare-earth phosphors is an effective strategy to target tailored optical performance.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hu T., Gao Y., Molokeev M. S., Xia Z., Zhang Q.
Заглавие : Non-stoichiometry in Ca2Al2SiO7 enabling mixed-valent europium toward ratiometric temperature sensing
Место публикации : Sci. China Mater. - 2019. - Vol. 62, Is. 12. - P.1807–1814. - ISSN 20958226 (ISSN), DOI 10.1007/s40843-019-1202-x
Примечания : Cited References: 53. - This work was supported by the National Natural Science Foundation of China (51722202, 51972118 and 51572023), the Guangdong Provincial Science & Technology Project (2018A050506004), and Innovation Projects of Department of Education of Guangdong Province (2018KQNCX265).
Аннотация: Eu2+/Eu3+ mixed-valence couple co-doped material holds great potential for ratiometric temperature sensing owing to its different electronic configurations and electron-lattice interaction. Here, the correlation of nonstoichiometry in chemical composition, phase structures and luminescence propertis of Ca2Al2Si1−xO7:Eu is discussed, and controlled Eu2+/Eu3+ valence and tunable emission appear with decreasing Si content. It is found that the 2Ca2+ + Si4+ ↔ Eu2+ + Eu3+ + Al3+ cosubstitution accounts for the structural stability and charge balance mechanism. Benefiting from the diverse thermal dependent emission behaviors of Eu2+ and Eu3+, Ca2Al2Si1−xO7:Eu thermometer exhibits excellent temperature sensing performances with the maximum absolute and relative sensitivity being 0.024 K−1 (at 303 K) and 2.46% K−1 (at 443 K) and good signal discriminability. We propose that the emission quenching of Eu2+ is ascribed to 5d electrons depopulation through Eu2+/Eu3+ intervalence charge transfer state, while the quenching of Eu3+ comes from multi phonon relaxation. Our work demonstrates the potential of Ca2Al2Si1−xO7:Eu for noncontact optical thermometry, and also highlights mixed valence europium containing com pounds toward temperature sensing.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lim, Chang Sung, Aleksandrovsky A. S., Atuchin V. V., Molokeev M. S., Oreshonkov A. S.
Заглавие : Microwave sol-gel synthesis, microstructural and spectroscopic properties of scheelite-type ternary molybdate upconversion phosphor NaPbLa(MoO4)3:Er3+/Yb3+
Место публикации : J. Alloys Compd. - 2020. - Vol. 826. - Ст.152095. - ISSN 0925-8388 (ISSN), DOI 10.1016/j.jallcom.2019.152095. - ISSN 1873-4669 (eISSN)
Примечания : Cited References: 53. - This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2018R1D1A1A09082321). This study was supported by the Russian Science Foundation (19-42-02003, in part of conceptualization). Also, this study was supported by RFBR (18-32-20011, 18-03-00750).
Аннотация: New ternary molybdate NaPbLa(1-x-y)(MoO4)3:xEr3+,yYb3+ (x = y = 0, x = 0.05 and y = 0.35, 0.4, 0.45 and 0.5) phosphors were successfully fabricated by the MSG (microwave sol-gel) method, and the microstructural and spectroscopic properties were characterized. The crystal structure of NaPbLa(MoO4)3 (NPLM) was defined by Rietveld analysis in space group I41/a with unit cell parameters a = 5.3735(2) and c = 11.8668(4) Å, V = 342.65(3) Å3, Z = 4 (RB = 6.64%). The unit cell volume of NaPbLa(MoO4)3 (NPLM) was intermediate between those of NaLa(MoO4)2 and PbMoO4. Under the 980 nm excitation, upconverted yellowish-green emissions at transitions from 2H11/2 and 4S3/2 were observed. No concentration quenching in the subsystem of donor ions at the content up to 50 at.% and no cross-relaxation losses in the subsystem of acceptor ions at the concentrations as high as 5 at. % were verified. The individual chromaticity points for the NaPbLa(MoO4)3:Er3+,Yb3+ phosphors, corresponding to the equal-energy point in the standard CIE diagram, revealed yellowish-green emissions.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou, Guojun, Jiang, Xingxing, Molokeev M. S., Lin, Zheshuai, Zhao, Jing, Wang, Jing, Xia, Zhiguo
Заглавие : Optically Modulated Ultra-Broad-Band Warm White Emission in Mn2+-Doped (C6H18N2O2)PbBr4 Hybrid Metal Halide Phosphor
Место публикации : Chem. Mater. - 2019. - Vol. 31, Is. 15. - P.5788-5795. - ISSN 0897-4756, DOI 10.1021/acs.chemmater.9b01864. - ISSN 1520-5002(eISSN)
Примечания : Cited References: 47. - This work is supported by the National Natural Science Foundation of China (nos. 51722202 and 51572023), Natural Science Foundations of Beijing (2172036), the Fundamental Research Funds for the Central Universities (FRF-TP-18-002C1), and the Guangdong Provincial Science & Technology Project (no. 2018A050506004).
Предметные рубрики: LIGHT EMISSION
PEROVSKITE NANOCRYSTALS
ENERGY-TRANSFER
STATE
Br
Аннотация: Finding new low-dimensional metal halides with broad-band emission is attracting interest in single-component phosphor for white light-emitting diodes (WLEDs). The full-spectrum white light still remains a challenge as found in the two-dimensional hybrid material (C6H18N2O2)PbBr4 exhibiting the intrinsic free exciton (FE) and broad-band self-trap exciton (STE) emission upon 365 nm ultraviolet excitation, and a combined strategy has been proposed through doping the Mn2+ ions enabling a superposition of multiple emission centers toward the ultra-broad-band warm white light. The occupation of Mn2+ in (C6H18N2O2)PbBr4 has been discussed, and optical investigations verify that the warm white-light emission of Mn2+-doped (C6H18N2O2)PbBr4 originates from the coupling effects of the FE, STEs, and the 4T1–6A1 transition of the doped Mn2+. When the concentration of Mn2+ is 5%, the emission spectrum of the phosphor covers all visible-light areas with a full width at half maximum (FWHM) of about 230 nm. The high Ra (84.9) and warm light CCT (3577 K) values of the as-fabricated WLED lamp demonstrate that (C6H18N2O2)Pb1–xMnxBr4 can be promising as single-component white-light phosphor in solid-state lighting. Our work could provide a new understanding and perspective about hybrid metal halides for designing superior phosphor toward single-component white emission.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Su, Binbin, Molokeev M. S., Xia, Zhiguo
Заглавие : Mn2+-Based narrow-band green-emitting Cs3MnBr5 phosphor and the performance optimization by Zn2+ alloying
Место публикации : J. Mater. Chem. C. - 2019. - Vol. 7, Is. 36. - P.11220-11226. - ISSN 2050-7526, DOI 10.1039/c9tc04127c. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 24. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51722202, 51972118 and 51572023), Natural Science Foundations of Beijing (2172036) and the Guangdong Provincial Science & Technology Project (no. 2018A050506004).
Предметные рубрики: THERMAL-STABILITY
BACKLIGHT
EMISSION
Аннотация: To discover new narrow-band green-emitting phosphors is a challenge for backlighting light-emitting diodes (LEDs) used in liquid crystal displays (LCDs). The synthesis and optical properties of Cs3MnBr5 are demonstrated herein. The intrinsic Mn2+ luminescence without concentration quenching leads to intense green emission at 520 nm with narrow full width at half maximum of 42 nm and high photoluminescence quantum yield (PLQY) of 49% under the excitation at 460 nm. When a small amount of Zn2+ is introduced into Cs3MnBr5, the luminescence intensity decreases slightly. However, the thermal stability of Cs3MnBr5 is improved from 82% to 87% with the intensity values at 423 K compared to that at 298 K. The white LED device fabricated using Cs3Mn0.96Zn0.04Br5 (green) and K2SiF6:Mn4+ (red) phosphors with a blue LED chip exhibit a high luminous efficiency (107.76 lm W-1) and wide color gamut (101% National Television System Committee standard (NTSC) in Commission Internationale de L'Eclairage (CIE) 1931 color space), demonstrating its potential application in wide color gamut LCD backlights.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yang, Xiang, Zhang, Y.u., Zhang, Xuejie, Chen, Jian, Huang, Haisen, Wang, Dongsheng, Chai, Xirong, Xie, Gening, Molokeev M. S., Zhang, Haoran, Liu, Yingliang, Lei, Bingfu
Заглавие : Facile synthesis of the desired red phosphor Li2Ca2Mg2Si2N6:Eu2+ for high CRI white LEDs and plant growth LED device
Место публикации : J. Am. Ceram. Soc. - 2020. - Vol. 103, Is. 3. - P.1773-1781. - ISSN 0002-7820, DOI 10.1111/jace.16858. - ISSN 1551-2916(eISSN)
Примечания : Cited References: 34. - National Natural Science Foundations of China, Grant/Award Number: 21671070 and 51802101; Project GDUPS; Natural Science Foundation of Guangdong Province, Grant/Award Number: 2018A030310217; Guangzhou Science & Technology Project, Grant/Award Number: 201704030086; Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams; National Undergraduate Innovation and Entrepreneurship Training Program granted for Gening Xie, Grant/Award Number: 201910564035
Предметные рубрики: IN-GLASS
LUMINESCENCE
PERFORMANCE
EFFICIENT
EMISSION
ROUTE
Аннотация: The red emission with suitable peak wavelength and narrow band is acutely required for high color rendering index (CRI) white LEDs without at the cost of the luminous efficacy. Herein, the Li2Ca2Mg2Si2N6:Eu2+ red phosphor was prepared with facile solid‐state method using Ca3N2, Mg3N2, Si3N4, Li3N, and Eu2O3 as the safety raw materials under atmospheric pressure for the first time, which shows red emission peaking at 638 nm with full width at half maximum (FWHM) of 62 nm under blue light irradiation and becomes the desired red phosphor to realize the balance between luminous efficacy and high CRI in white LEDs. The morphology, structure, luminescence properties, thermal quenching behavior, and chromaticity stability of the Li2Ca2Mg2Si2N6:Eu2+ phosphor are investigated in detail. Concentration quenching occurs when the Eu2+ content exceeds 1.0 mol%, whereas high‐temperature photoluminescent measurements show a 32% drop from the room‐temperature efficiency at 423 K. In view of the excellent luminescence performances of Li2Ca2Mg2Si2N6:Eu2+ phosphor, a white LEDs with CRI of 91 as a proof‐of‐concept experiment was fabricated by coating the title phosphor with Y3Al5O12:Ce3+ on a blue LED chip. In addition, the potential application of the title phosphor in plant growth LED device was also demonstrated. All the results indicate that Li2Ca2Mg2Si2N6:Eu2+ is a promising red‐emitting phosphor for blue LED‐based high CRI white LEDs and plant growth lighting sources.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji, Haipeng, Hou, Xinghui, Molokeev M. S., Ueda, Jumpei, Tanabe, Setsuhisa, Brik M. G., Zhang, Zongtao, Wang, Y.u., Chen, Deliang
Заглавие : Ultrabroadband red luminescence of Mn4+ in MgAl2O4 peaking at 651 nm
Место публикации : Dalton Trans. - 2020. - Vol. 49, Is. 17. - P.5711-5721. - ISSN 1477-9226, DOI 10.1039/d0dt00931h. - ISSN 1477-9234(eISSN)
Примечания : Cited References: 54. - This study was partly supported by the National Natural Science Foundation of China (Grant No. 51902291 and 51574205), the China Postdoctoral Science Foundation (2019M662524, 2019M652574), the Postdoctoral Research Sponsorship in Henan Province (19030025, 001802045), the Natural Science Foundation of Guangdong Province (2018B030311022), the Guangdong Innovation Research Team for Higher Education (2017KCXTD030), and the High-level Talents Project of Dongguan University of Technology (KCYKYQD2017017). J. U. and S. T. were also supported by the JSPS KAKENHI (16H06441, 19H02798) and M. M. was also supported by the RFBR (19-52-80003).
Предметные рубрики: EMITTING PHOSPHOR
PHOTOLUMINESCENCE PROPERTIES
PHASE-TRANSITION
Аннотация: Blue light pumped red luminescence with broadband and high photon-energy emission is highly desired for phosphor-converted white light-emitting diodes (pc-wLEDs), to achieve a high color rendering index and high luminous efficacy. Mn4+-doped red-emitting phosphors generally exhibit sharp vibronic emissions associated with the parity- and spin-forbidden 2Eg → 4A2g transitions. In this paper, two abnormal luminescence behaviors were observed for Mn4+ in the MgAl2O4:Mn4+ spinel phosphor with a short wavelength emission band peaking at 651 nm. Firstly, the Mn4+ 2Eg → 4A2g transition exhibits ultrabroadband luminescence in MgAl2O4 and the large full-width at half-maximum (FWHM) is dependent both on the calcination temperature and on the partial substitution of Al3+ with Ga3+. Secondly, the thermal quenching behavior of the Mn4+ 2Eg → 4A2g luminescence in MgAl2O4 shows a dependence on its thermal treatment and preparation method. The Rietveld refinement and Raman results demonstrate that the variation in the FWHM of the luminescence spectra is a sum effect of structural ordering (i.e., isotropic displacement decrease of constituent atoms) and the Mg ↔ Al anti-site disorder. A model for the observed varying thermal quenching of luminescence was tentatively proposed. The intrinsic thermal quenching temperature of Mn4+ luminescence in MgAl2O4 was found to be 390–400 K using the samples prepared by the co-precipitation and molten salt methods. The present work gives a novel perspective to understand the luminescence spectra of Mn4+ 2Eg → 4A2g transition.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gu S., Xia M., Zhou C., Kong Z., Molokeev M. S., Liu L., Wong W. -Y., Zhou Z.
Заглавие : Red shift properties, crystal field theory and nephelauxetic effect on Mn4+-doped SrMgAl10-yGayO17 red phosphor for plant growth LED light
Место публикации : Chem. Eng. J. - 2020. - Vol. 396. - Ст.125208. - ISSN 13858947 (ISSN), DOI 10.1016/j.cej.2020.125208
Примечания : Cited References: 54. - The authors would like to gratefully acknowledge funds from the National Natural Science Foundation of China (Grant No. 21706060 , 51703061 , 51974123 ), the Hunan Graduate Research and Innovation Project (Grant No. CX2018B396 ), the Hunan provincial Engineering Technology Research Center for Optical Agriculture (Grant No. 2018TP2003 ), the Scientific Research Fund of Hunan Provincial Education Department (15K058, 19C0903 ), the Natural Sciences Foundation of Hunan agricultural university, China (Grant No. 19QN11 ), Science and Technology project of Changsha ( KH1801219 ), Huxiang high level talent gathering project ( 2019RS1077 ), Double first-class construction project of Hunan Agricultural University (SYL201802002&SYL201802002). L. Liu thanks the National Natural Science Foundation of China ( 21671061 ) and application foundation frontier special project by Wuhan Science and Technology Bureau ( 2019010701011414 ) for the support of this work. W.-Y. Wong acknowledges the financial support from the Hong Kong Research Grants Council (C4006-17G and PolyU 153058/19P), the Hong Kong Polytechnic University ( 1-ZE1C ) and Ms Clarea Au for the Endowed Professorship in Energy (847S)
Аннотация: The discovery of novel Mn4+-doped oxide red phosphor with suitable spectrum for plant growth is a hot issue in the recent years due to the characteristic red photoluminescence of 2Eg → 4A2 transition in Mn4+ ions. Generally, the emission position of Mn4+ is hard to tune because of specific crystal field in most phosphors. In this work, tunable luminescence property with obvious red shift in the spectra is observed in the Mn4+-doped SrMgAl10-yGayO17 red phosphor via simple substitution of Ga3+ for Al3+, and crystal field theory and nephelauxetic effect are employed to explain this phenomenon. Meanwhile, the Ga3+ dopant changes the shape of the spectra because Ga3+ dopant guides the replacement site of Mn4+ and changes the luminescence center. Improved emission intensity is obtained because appropriate Ga3+ doping leads to larger band gap and reduces non-radiative transitions. Phosphor-converted LED (pc-LED) devices fabricated with blue chip (470 nm) and the as-obtained SrMgAl10-yGayO17:1.0%Mn4+ phosphors emit bright blue and red light, which fit the absorption regions of plant pigments well, thus SrMgAl10-yGayO17:Mn4+ phosphor can be a candidate for plant growth LED light.
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