5 results on '"Lei, Lei"'
Search Results
2. Enhanced up-conversion luminescence intensity in single-crystal SrTiO3: Er3+ nanocubes by codoping with Yb3+ ions.
- Author
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Xiao, Zhen, Zhang, Jiawei, Jin, Lei, Xia, Yang, Lei, Lei, Wang, Huanping, Zhang, Junjie, and Xu, Shiqing
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SINGLE crystals , *PHOTON upconversion , *LUMINESCENCE , *STRONTIUM titanate , *ERBIUM , *DOPING agents (Chemistry) , *YTTERBIUM ions - Abstract
A series of Er 3+ doped and Er 3+ /Yb 3+ codoped SrTiO 3 nanocubes with varying dopant concentrations have been successfully synthesized by a facile hydrothermal method. The doping effects on phase purity, morphology and microstructure of samples were identified by power X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that SrTiO 3 nanocubes have a typical perovskite structure with the edge length ranging 20–50 nm. The Er 3+ and Yb 3+ ions were successfully doped into the crystal lattice of SrTiO 3 , but did not alter crystal structure of SrTiO 3 . The photon up-conversion (UC) photoluminescence (PL) measurements indicated that the intense green light emission of Er 3+ ions around 525 nm, 550 nm and red light emission centered at 670 nm in UC processes populated by 980 nm laser excitation have been achieved in SrTiO 3 nanocubes. Moreover, the PL intensity of Er 3+ -doped SrTiO 3 nanocubes was greatly enhanced while introducing the Yb 3+ to the crystal structure, especially the red emission. The mechanisms for these emissions probably due to the excited state absorption (ESA) and energy transfer (ET) process. Er 3+ /Yb 3+ -codoped single-crystal perovskite SrTiO 3 nanocubes could be interesting objects for applications in mechanical−electrical luminescence such as electric field modulation luminescence and mechanoluminescence. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
3. The growth and luminescence mechanism of novel near-infrared Cs4Eu(Br,I)6:Sm crystal.
- Author
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Huang, Xinshuai, Wei, Qinhua, Yang, Jienan, Tang, Gao, Cai, Peiqing, Lei, Lei, Chen, Zhenhua, Liu, Zugang, Qin, Laishun, and Shi, Hongsheng
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SAMARIUM , *LUMINESCENCE , *SINGLE crystals , *CRYSTALS , *ENERGY transfer , *SCINTILLATORS - Abstract
A novel NIR emitting scintillator with 825 nm was developed by doping Sm2+ in Cs 4 Eu(Br,I) 6 crystal. The single crystals of Cs 4 Eu(Br,I) 6 :Sm were successfully grown by the Bridgman method. The crystal structure and valence state was approved by XRD and XPS methods. The luminescence properties and energy transfer were systematically investigated. The energy transfer mechanism is variable for different Sm2+ concentration. The PL decay profiles show that the Sm2+-related emission has fast decay of nanosecond. The proportion of fast decay can be tunable by adjusting Sm2+ doped concentration. The Sm2+ doped europium -host material will have a potential application for unclear detection as near-infrared (NIR) scintillators. • The novel NIR emitting Cs 4 Eu(Br,I) 6 :Sm scintillation crystals were successfully grown by the Bridgman method and the luminescence properties is tunable. • The proportion of nonradiative energy transfer from Eu2+ to Sm2+ was improved and the PLQY of Sm2+-related is up to 42.1%. • The fast decay time component of Sm2+ (50 ns) is up to 31.8% for Cs 4 Eu(Br,I) 6 : 3 mol%Sm crystal. • The proposed Sm2+ doped europium -host material principle is an effective method to develop near-infrared (NIR) scintillators for nuclear radiation detection. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Temperature-dependent luminescence of Bi3+, Eu3+ co-activated La2MgGeO6 phosphor for dual-mode optical thermometry.
- Author
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Chen, Yanling, Shen, Yuyu, Zhou, Liuyan, Lin, Jianhua, Fu, Jie, Fang, Qianglong, Ye, Renguang, Shen, Yang, Xu, Shiqing, Lei, Lei, and Deng, Degang
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PHOSPHORS , *OPTICAL materials , *THERMOMETRY , *LUMINESCENCE spectroscopy , *ENERGY transfer , *MOLECULAR spectra , *LUMINESCENCE - Abstract
Using a high-temperature solid-phase method, a series of La 2 MgGeO 6 : Bi3+, Eu3+ samples with different doping amounts of Bi3+ and Eu3+ were obtained. The crystal structure, morphology, luminescence characteristics, temperature-varying luminescence spectrum, fluorescence attenuation curve, and energy transfer mechanism of the samples were explored. In La 2 MgGeO 6 : Bi3+, Eu3+ phosphors, Bi3+ and Eu3+ ions occupy the La3+ ion position. Under ultraviolet (UV) excitation, the emission spectra of LMGO: Bi3+ and the excitation spectra of LMGO: Eu3+ have significant spectral overlap, indicating that there is energy transfer between Bi3+ and Eu3+. By adjusting the doping amounts of Eu3+, adjustable luminescence can be obtained in the co-doped samples. According to the varying temperature-dependence trends of Bi3+ and Eu3+ ions, fluorescence intensity ratio technology was used to explore the temperature-sensing characteristics of Bi3+ and Eu3+ ions. The maximum absolute sensitivity and relative sensitivity were 0.074%·K−1 and 2.389%·K−1, respectively. In addition, by monitoring the lifetime decay time of Bi3+ with temperature, the maximum temperature sensitivity of the La 2 MgGeO 6 : Bi3+ samples was 4.09%·K−1. The above results indicate that La 2 MgGeO 6 : Bi3+, Eu3+ samples can be used as potential luminescent materials for temperature detection. • La 2 MgGeO 6 : Bi3+, Eu3+ is explored to be a very promising optical thermometric materials. • The LMGO: Bi3+, Eu3+ shows high signal discriminability in the blue and red regions. • The LMGO: Bi3+, Eu3+ phosphors can circumvent the drawbacks of TCL-based phosphors. • The fluorescence intensity ratio and decay life of the material are highly sensitive to temperature. • The thermal-quenching mechanism of Bi3+ and Eu3+ were discussed. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
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5. Tunable photoluminescence and temperature sensing properties of Ce3+, Eu2+ co-doped Ca2-xSrxMgSi2O7 phosphors.
- Author
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Zhou, Liuyan, Liu, Fuwen, Ye, Renguang, Lei, Lei, Guo, Weigang, Chen, Liang, Deng, Degang, and Xu, Shiqing
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PHOSPHORS , *PHOTOLUMINESCENCE , *OPTICAL materials , *OPTICAL properties , *ENERGY transfer , *LUMINESCENCE , *SOLID solutions - Abstract
A series of Ca 2- x Sr x MgSi 2 O 7 : Ce3+, Eu2+ (x = 0, 0.5, 1, 1.5, 2) phosphors were synthesized on the basis of high temperature solid-state reaction strategy. Its phase composition, optical spectral properties, fluorescence lifetime and temperature sensitivity were investigated in detail. Under excitation at 342 nm, the emission spectra of Ca 2 MgSi 2 O 7 : Ce3+, Eu2+ exhibit a purple emission band (Ce3+ ions) and a green emission band (Eu2+ ions). The emission band of Ce3+ overlaps with the excitation band of Eu2+, indicating that there may be energy transfer (ET) between the two ions. The decreasing fluorescence lifetime of Ce3+ with increasing Eu2+ concentration further proves the existent of ET process in Ca 2 MgSi 2 O 7 : Ce3+, Eu2+ phosphor. In addition, Ca 2- x Sr x MgSi 2 O 7 : Ce3+, Eu2+ solid solution was designed and synthesized by Sr2+ substituting Ca2+. As Sr2+ gradually replaced Ca2+, the blue-shift of Ce3+ and Eu2+emission band were caused by the change of crystal field. With the increase of temperature, the fluorescence intensity of Ce3+ and Eu2+ emission bands decreased slowly and rapidly, respectively. Hence, in the Ce3+/Eu2+ co-activated Ca 2- x Sr x MgSi 2 O 7 phosphor, Ce3+ ions and Eu2+ ions can be used as fluorescence intensity ratio (FIR) signals. The maximum relative sensitivity can reach 2.43% K−1 (at 293 K) under 342 nm excitation. The above results indicate that Ca 2- x Sr x MgSi 2 O 7 : Ce3+, Eu2+ phosphors are potential candidates for optical thermometer materials. • The Ca 2- x Sr x MgSi 2 O 7 : Ce3+, Eu2+ (x = 0, 0.5, 1, 1.5, 2) phosphors are promising optical thermometric materials. • The emission peaks of Ce3+ and Eu2+ blue-shift due to the change of crystal field caused by Sr2+ replacing Ca2+. • FIR based on dual luminescence center can overcome the disadvantage of fluorescence intensity ratio based on TCL. • The thermal-quenching mechanism of Ce3+ and Eu2+ were discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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