CRYSTENGCOMM
·
2023
·Vol. 25
·期 40
·5730-5739
·
IF 3.1
Ying Chen,Xuegang Zheng,Meijuan Liu,Haobo Lin,Shusheng Pan,Weiwei Xing,Zhiyu Liu,Dekang Xu,Hao Lin
In previous studies, LiErF4 mostly served as a dipolar-coupled antiferromagnet and was less commonly used as a luminescent material to study the luminescence performance. Therefore, there are few research reports on the luminescent properties of LiErF4 materials at this stage. In this work, the LiErF4:Ce,Yb,Y@LiYbF4:Tm@LiYF4 core/shell/shell upconversion nanoparticles (UCNPs) and the relevant derivative samples were successfully prepared by coprecipitation method. The LiErF4:Ce,Yb,Y@LiYbF4:Tm@LiYF4 UCNPs exhibit a prominent emission peak at 792 nm and several weak emission peaks in the visible light region under irradiation at 980 nm. Here, the cross relaxation between Ce3+ and Er3+ in the core can effectively reduce unwanted visible light emissions (4S3/2 + 2F5/2 → 4F9/2 + 2F7/2, 4F9/2 + 2F5/2 → 4I9/2 + 2F7/2, 4I9/2 + 2F5/2 → 4I11/2 + 2F7/2, 4I11/2 + 2F5/2 → 4I13/2 + 2F7/2). The Yb3+ ions not only work as an energy transfer medium promoting energy transfer, but also as an energy harvester effectively absorbing excitation energy, which can improve energy utilization and promote first near-infrared (NIR-I) emission. The intensity of NIR-I and the ratio of NIR-I to visible light are increased due to the cross relaxation between Ce3+ and Er3+ and the energy migration among Yb3+. The UCNPs emitting strong NIR-I light are advisable for biological imaging.
研究领域:
材料科学
·
光学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
ChemistrySelect
·
2022
·Vol. 7
·期 41
·e202202378
·
IF 2.307
Lin Gan,Youfa Wang
Graphical The upconversion luminescence intensity of LiErF 4 was enhanced by a suitable Gd 3+ content which is too low for LiGdF 4 synthesis. Considering the enhanced upconversion emission of LiErF 4 and synthesis of pure tetragonal phase LiGdF 4 , a core–shell structure of LiErF 4 @LiGdF 4 :Yb,Er was designed and a series of relevant derivatives with red-to-green tunable upconversion luminescence were obtained. In this study, LiErF 4 and related LiGdF 4 core-shell nanocrystals were synthesized via thermal decomposition, and the upconversion luminescence under an excitation of 980 nm was investigated. The phase of LiErF 4 was not changed by a low content of Gd 3+ dopant, whereas orthorhombic GdF 3 formed as an impurity when the amount of Gd 3+ was increased. The upconversion luminescence intensity of LiErF 4 was enhanced by a suitable Gd 3+ content. Considering the enhanced upconversion emission of LiErF 4 and synthesis of pure tetragonal phase LiGdF 4 , a core–shell structure of LiErF 4 @LiGdF 4 :Yb,Er was designed, characterized, and compared to LiYF 4 @LiGdF 4 :Yb,Er. LiErF 4 @LiGdF 4 :Yb,Er had a yellow upconversion emission output, which was attributed to the combination of the upconversions in the core and shell. Additionally, a series of relevant derivatives of LiErF 4 @LiGdF 4 :Yb,Er were prepared for further investigation of their luminescence performance, and red-to-green tunable upconversion luminescence was obtained for these core–shell nanocrystals.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2024
·Vol. 26
·期 10
·1371-1379
·
IF 2.6
Meijuan Liu,Ying Chen,Xuegang Zheng,Haonan Zhao,Shusheng Pan,Zhiyu Liu,Dekang Xu,Hao Lin
In this study, a series of LiErF4:Tm@LiYF4:Yb,Er,Ce@LiYF4 core/shell/shell (C/S/S) UC nanoparticles (UCNPs) were prepared by a co-precipitation method. In this design of C/S/S structure, Er3+ is used as an energy collector in the first shell, which can reduce the energy loss by absorbing spontaneous emission from Yb3+. Then, by adding appropriate concentrations of Ce3+ into the same shell, the cross relaxation effect between Er3+ and Ce3+ is exploited to improve the efficiency of Er3+ in collecting the energy of spontaneous emission from Yb3+. During the upconversion (UC) process, Yb3+ plays a role as an energy transfer bridge, transferring the energy back to Er3+ in the core, thus enhancing the red UC emission intensity. Meanwhile, Tm3+ acts as an energy trapping center that contributes to the red emission. The results show that the spontaneous emission loss of Yb3+ has a certain effect on the UC fluorescence intensity, which will weaken the fluorescence to some extent, however is not the cause of the substantial decay of fluorescence. Therefore, this study provides clues for researchers to identify main factors affecting the luminescence efficiency, which will help develop more efficient UCNPs.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Nano Research
·
2020
·Vol. 13
·期 10
·2803-2811
·
IF 8.183
Zhang Ling,Li Xiaodan,Wang Wang,Zhao Xu,Yan Xu,Wang Chenguang,Bao Haoqiang,Lu Yang,Kong Xianggui,Liu Fengmin,Liu Xiaomin,Lu Geyu
LiErF 4 was commonly used as a dipolar-coupled antiferromagnet, and was rarely considered as a luminescent material. Herein, we achieved the strong red upconversion emission of LiErF 4 simply by an inert shell coating, i.e., LiErF 4 @LiYF 4 . Owing to the unique and intrinsic ladder-like energy levels of Er 3+ ions, this LiErF 4 core-shell nanostructures present red emission (∼ 650 nm) under multi-band excitation in the near-infrared (NIR) region (∼ 808, ∼ 980, and ∼ 1,530 nm). A brighter and monochromic red emission can be further obtained via doping 0.5% Tm 3+ into the LiErF 4 core, i.e., LiErF 4 : 0.5% Tm 3+ @LiYF 4 . The enriched Er 3+ ions and strong monochromic red emission natures make LiErF 4 : 0.5% Tm 3+ @LiYF 4 nanocrystals very sensitive for trace water probing in organic solvents with detection limit of 30 ppm in acetonitrile, 50 ppm in dimethyl sulfoxide (DMSO), and 58 ppm in N , N -dimethylformamide (DMF) under excitation of 808 nm. Due to their superior chemical and physical stability, these nanoprobes exhibit excellent antijamming ability and recyclability, offering them suitable for real-time and long-term water monitoring.
研究领域:
材料科学
·
分析化学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Advanced Optical Materials
·
2023
·Vol. 11
·期 10
·2202884
·
IF 9
Ling Zhang,Zhongling Lang,Yang Lu,Xu Zhao,Bin Jiang,Xu Yan,Peng Sun,Fengmin Liu,Guangdong Zhou,Mi Zhou,Yanchao Wang,Xiaomin Liu,Geyu Lu
Local structural engineering is an endogenous approach to modulate upconversion luminescence (UCL) from upstream to meet the needs of specific application scenarios. Herein, high pressure is utilized as a means to modulate the local structure, and the designed LiErF 4 :0.5%Tm 3+ @LiYF 4 (Er:Tm@Y) nanoparticles with fast energy transfer rates, abundant cross-relaxation processes, and multiple near-infrared wavelengths (808, 980, 1530 nm) excitation properties are tailored as local structure-sensitive hosts. A unique excitation wavelength-dependent UCL enhancement of Er:Tm@Y upconversion nanoparticles is observed by pressure-induced local structure distortions. When the pressure of ≈6 GPa is applied, the UCL is enhanced by a factor of 2.6 at 980 nm excitation only. After pressure release, the luminescence diminishes and recovers. Density functional theory calculations show that the symmetry distortion of the LiErF 4 crystal reaches a maximum at pressurization to 6 GPa, while a new Er-4f state emerges, greatly reducing the bandgap from 8.3 to 5.7 eV. Comparative experiments demonstrate that the local symmetry distortion caused by 0.5%Tm 3+ doping and the different energy transfer patterns of Er 3+ to Tm 3+ at different excitations are responsible for this wavelength-dependent luminescence enhancement.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）