JOURNAL OF FLUORINE CHEMISTRY
·
2023
·
IF 1.9
Shuang Wu,Yanhui Dong,Hao Cui,Daguang Li,Weiping Qin
The morphology and size of LiYF 4 :Yb,Er nanoparticles were controlled using an automatic nanomaterial synthesizer by changing the reaction time at high temperature. It was found that the nanoparticles underwent a growth and change process from small to large and then to small, and then remained at a basically stable size, reflecting the different growth stages of the nanoparticles, such as nucleation, growth, phase transition, and internal Ostwald ripening, etc. XRD analyses showed that LiF nanocrystals were first formed during the reaction process, and then all the products were converted into LiYF 4 nanocrystals. Under the excitation of a 980 nm laser, the LiYF 4 :Yb,Er nanoparticles showed regular downconversion and upconversion luminescence properties, which was basically consistent with the regularity of nanocrystal growth. The experimental results showed that the upconversion luminescence and downconversion luminescence intensities of nanocrystals increasd rapidly when the synthesis time was between 0 and 50 min, and they increased slowly after the synthesis time exceeded 50 min.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2017
·
IF 4.536
Yiru Zhu,Shuwen Zhao,Bin Zhou,Hao Zhu,Youfa Wang
In this work, we report a phenomenon that upconversion emission intensity of Er3+ was enhanced by cadmium. Cd2+ was taken with 0, 3, 10, 20, 30, and 40 mol % as a new dopant to codope LiY0.78Yb0.20Er0.02F4, meanwhile the doping effects on the crystal structure, morphology, and upconversion fluorescence emission are investigated by XRD, Rietveld refinement, TEM, and upconversion spectroscopy analysis methods in detail. The green upconversion emission intensity was enhanced, and the maximum emission intensities were enhanced to twice when 10 mol % Cd2+ was codoped into tetragonal LiYF4, while its decay lifetime was reduced. Additionally, we further designed the synthesis of the homogeneous LiYF4:20%Yb,2%Er,10%Cd@LiYF4 of which the emission intensity is 11 times higher than that of the Cd2+-free nanocrystals, meanwhile an intriguing morphology of core–shell nanocrystals was obtained. This investigation may be useful for the design and improvement of upconversion materials for fulfilling the prerequisite of the practical application.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Maohui Yuan,Kai Han,Linxuan Wang,Xu Yang,Zining Yang,Hongyan Wang,Xiaojun Xu
Lanthanide-based optical ratiometric thermometer is a promising temperature detecting tool for noninvasive temperature measurements. However, owing to the thermal quenching of upconversion luminescence (UCL), the traditional temperature sensing range is limited to less than 600 K. In this work, highly thermally stable UCL is observed through introduced appropriate Cu 2+ ions into LiYF 4 :Yb/Er (20/2 mol%) microcrystals (MCs) and on which are further used for temperature sensing applications. As gradually increases the doping of Cu 2+ ions, the octahedron morphology of LiYF 4 MCs with smooth surfaces gradually aggregates smaller particles on their surface forming diamond-like micro-clusters. Based on the single-particle spectroscopy technique , the temperature-dependent UCL properties were systematically investigated and demonstrated. Doping of Cu 2+ ions can efficiently adjust and enhance the UCL in the LiYF 4 :Yb/Er (20/2 mol%) MCs. The UCL thermal quenching temperature is less than ~670 K for Cu 2+ -free MCs. In contrast, the quenching temperature extends to as high as ~870 K when doping with 2 mol% Cu 2+ ions. Furthermore, these highly thermal stable MCs are utilized to detect the temperature in a wide temperature ranging from 298 K to 873 K. A maximum relative sensitivity ( S r ) of 1.23%K −1 at 298 K is obtained and temperature uncertainty δ T < 0.091 K is determined under the measured temperature for the 2 mol% Cu 2+ -doped MCs. The highly thermally stable UCL properties and excellent thermometer performance of these MCs, particularly conducted at single-particle spectroscopy technique , can be potentially applied to micro-scale thermometers.
✓ 已验证
DOI
高影响因子
Nanoscale
·
2017
·Vol. 10
·期 6
·2834-2840
·
IF 7.367
Bin Zhou,Bing Xu,Huimei He,Zhanjun Gu,Bing Tang,Ying Ma,Tianyou Zhai
We report the enhancement of green upconversion luminescence in tetrahedral LiYF4:Yb/Er nanoparticles by Mn2+ ion doping, which is different from the enhanced single-band red emission dominated by Mn2+ ions in cubic NaLnF4:Yb/Er (Ln = Y, Gd, Lu) nanoparticles. The energy levels of the first excited state 4T1 of Mn2+ in tetrahedral LiYF4:Gd and cubic NaGd(Y)F4 are compared by detection of emissions from Mn2+via the energy transition from Gd3+ to Mn2+ with excitation at 275 nm. The coordination environments of Mn2+ in these two host lattices have been investigated by X-ray absorption fine structure measurements. The results demonstrate that the formation of tetrahedral MnF4 in tetragonal LiYF4 arising from the replacement of Ln3+ ions with Mn2+ ions leads to a higher energy level of the Mn2+ 4T1 state than that in octahedral MnF6 in cubic NaYF4. The high-lying excited state of tetrahedral MnF4 is close to the green emitting 4S3/2 state of Er3+ and thus enhances green upconversion emission in tetragonal LiYF4:Yb/Er, while the low-lying excited state of octahedral MnF6 dominates red emission in cubic NaYF4:Yb/Er. These findings provide direct evidence for the key roles of the host lattices and more possibilities in modulating the upconversion behaviour of lanthanide-based nanoparticles by transition-metal ion doping to achieve the desired goals of specific applications.
研究领域:
材料科学
·
光学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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