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A series of the hexagonal-phase NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0% Ce3+@NaLuF4:x%Yb3+ core-shell (CS) nanocrystals with codoping different Yb3+ ions in the shell is successfully built by a sequential growth process. The crystal structures and morphologies of samples are characterized by X-ray diffractometer and transmission electron microscope. With the Yb3+ ion concentration increasing from 0% to 15% in NaLuF4 shell, none of the crystal structures, sizes, and morphologies of the samples changes obviously because of the similarity in ionic radius between Yb3+ and the ions in shell and the low doping concentration. Under 980 nm near-infrared (NIR) excitation, the NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+ core nanocrystal produce green and red UC emission. And the red UC emission intensity is higher than green emission intensity. This is because two effective cross-relaxation processes happen between Ho3+ and Ce3+ ions, which results in the enhancement of the red emission. However, the overall emission intensity of NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+ nanocrystal decrease compared with that of the NaLuF4:20.0%Yb3+/2.0%Ho3+ nanocrystal. Thus, to further enhance the red UC emission intensity in NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+ nanocrystal, the NaLuF4:20.0%Yb3+/2.0% Ho3+/12.0%Ce3+@NaLuF4:x%Yb3+ CS nanocrystal are prepared for blocking the excitation and emission energy, transmitting surface quenching center and getting more excitation energy through doping Yb3+ ions in NaLuF4 shell. It can be clearly seen that the red UC emission intensity of CS nanocrystal first increases and then decreases with Yb3+ ion concentration increasing. Meanwhile, the corresponding red-to-green ratio increases from 4.9 to 5.6. The highest red UC emission intensity is observed in each of the NaLuF4:20.0%Yb3+ /2.0%Ho3+/12.0%Ce3+@NaLuF4:10%Yb3+ CS nanocrystal because the Ho3+ ions get more energy through the following three ways: 1) Yb3+ (core)-Ho3+ (core); 2) Yb3+ (shell)-Ho3+ (core); 3) Yb3+ (shell)-Yb3+ (core)-Ho3+ (core). Thus, building CS nanocrystals is one of the most effective approaches in order to improve the UC efficiency by suppressing the non-radiative decay of activators in the core and getting more excitation energy through different energy transfer ways. These NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@NaLuF4:Yb3+ CS nanocrystals with red UC emission have great potential applications in biological field and multi-primary color.
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Keywords:
- NaLuF4 nanocrystals /
- core-shell /
- upconversion emission /
- fluorescent enhancement
[1] Menyuk N, Dwight K, Pinaud F 1972 Appl. Phys. Lett. 21 159Google Scholar
[2] Downing E, Hesselink L, Ralston J, Macfarlane R A 1996 Science 273 1185Google Scholar
[3] Zhang Y, Zhang L, Deng R, Tian J, Zong Y, Jin D, Liu X G 2014 J. Am. Chem. Soc. 136 4893Google Scholar
[4] Zou W, Visser C, Maduro J A, Pshenichnikov M S, Hummelen J C 2012 Nat. Photon. 6 560Google Scholar
[5] Su Q, Feng W, Yang D, Li F 2017 Acc. Chem. Res. 50 32Google Scholar
[6] Huang B L, Dong H, Wong K L, Sun L D, Yan C H 2016 J. Phys. Chem. C 120 18858Google Scholar
[7] Niu N, Yang P P, He F, Zhang X, Gai S L, Li C X, Lin J 2012 J. Mater. Chem. 2 2
[8] 高当丽, 郑海荣, 田宇, 雷瑜, 崔敏, 何恩节, 张喜生 2010 中国科学: 物理学 力学 天文学 40 287
Gao D L, Zheng H R, Tian Y, Lei Y, Cui M, He E J, Zhang X S 2010 Sci. Sin.: Phys. Mech. Astron. 40 287
[9] Gao W, Zheng H R, He E J, Lu Y, Gao F Q 2014 J. Lumin. 152 44Google Scholar
[10] Teng X, Zhu Y H, Wei W, Wang S C, Huang J F, Naccache R, Hu W B, Tok A I Y, Han Y, Zhang Q C, Fan Q L, Huang W, Capobianco J A, Huang L 2012 J. Am. Chem. Soc. 134 8340Google Scholar
[11] Heer S, Kompe K, Gudel H U, Haase M 2004 Adv. Mater. 16 2102Google Scholar
[12] Mai H X, Zhang Y W, Sun L D, Yan C H 2007 J. Phys. Chem. C 111 13721Google Scholar
[13] Shi F, Wang J S, Zhai X S, Zhao D, Qin W P 2011 Cryst. Eng. Comm. 13 3782Google Scholar
[14] Yang T S, Sun Y, Liu Q, Feng W, Yang P Y, Li F Y 2012 Biomaterials 33 3733Google Scholar
[15] He E J, Zheng H R, Gao W, Tu Y X, Lu Y, Li G A 2013 Mater. Res. Bull. 48 3505Google Scholar
[16] Chang J, Liu Y, Li J, Wu S L, Niu W B, Zhang S F 2013 J. Mater. Chem. C 1 1168Google Scholar
[17] Gao D L, Zhang X Z, Zheng H R, Gao W, He E J 2013 J. Alloy. Compd. 554 395Google Scholar
[18] Gao W, Zheng H R, Han Q Y, He E J, Gao F Q, Wang R B 2014 J. Mater. Chem. C 2 5327Google Scholar
[19] 何恩节, 郑海荣, 高伟, 鹿盈, 李俊娜, 魏映, 王灯, 朱刚强 2013 62 237803Google Scholar
He E J, Zheng H R, Gao W, Lu Y, Li J N, Wei Y, Wang D, Zhu G Q 2013 Acta Phys. Sin. 62 237803Google Scholar
[20] Dong J, Gao W, Han Q Y, Wang Y K, Qi J X, Yan X W, Sun M T 2019 Rev. Phys. 4 100026Google Scholar
[21] Dong J, Zhang Z L, Zheng H R, Sun M T 2015 Nanophotonics 4 472
[22] Li Y, Wang G F, Pan K, Fan N Y, Liu S, Feng L 2013 RSC Adv. 3 1683Google Scholar
[23] Rai M, Singh S K, Singh A K, Prasad R, Koch B, Mishra K, Rai S B 2015 ACS Appl. Mater. Inter. 7 15339Google Scholar
[24] Zuo J, Li Q Q, Xue B, Li C X, Chang Y L, Zhang Y L, Liu X M, Tu L P, Zhang H, Kong X G 2017 Nanoscale 9 7941Google Scholar
[25] Yi G S, Lu H C, Zhao S Y, Ge Y, Yang W J, Chen D P, Guo L H 2004 Nano Lett. 4 2191Google Scholar
[26] Chen X, Peng D, Ju Q, Wang F 2015 Chem. Soc. Rev. 44 1318Google Scholar
[27] Gao W, Dong J, Liu J H, Yan X W 2016 Mater. Res. Bull. 80 256Google Scholar
[28] 高伟, 董军 2017 66 204206Google Scholar
Gao W, Dong J 2017 Acta Phys. Sin. 66 204206Google Scholar
[29] Hu H, Chen Z G, Cao T Y, Zhang Q, Yu M G, Li F Y, Yi T, Huang C H 2008 Nanotechnology 19 375702Google Scholar
[30] Sangeetha N M, van Veggel F C J M 2009 J. Phys. Chem. C 113 14702Google Scholar
[31] Ye S, Chen G Y, Shao W, Junle Q, Paras N P 2015 Nanoscale 7 3976Google Scholar
[32] Xie X G, Ga N G, Deng R R, Sun Q, Xu Q H, Liu X G 2013 J. Am. Chem. Soc. 135 12608Google Scholar
[33] Wang F, Deng R R, Wang J, Wang Q X, Han Y, Zhu H M, Chen X Y, Liu X G 2011 Nat. Mater. 10 968Google Scholar
[34] Vetrone B F, Naccache R, MahalingamV, Morgan C G, Capobianco J A 2009 Adv. Funct. Mater. 19 2924Google Scholar
[35] Gao W, Kong X Q, Han Q Y, Dong J, Zhang W W, Zhang B, Yan X W, Zhang Z L, He E J, Zheng H R 2018 J. Lumin. 196 186
[36] Dong J, Zhang J, Han Q Y, Zhao X, Yan X W, Liu J H, Ge H B, Gao W 2019 J. Lumin. 207 361Google Scholar
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图 1 (a) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+纳米晶体核, (b)−(e) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4:x%Yb3+(x = 0%, 5.0%, 10.0%, 15.0%)纳米核壳结构的XRD图谱
Figure 1. XRD patterns of (a) NaLuF4:20.0%Yb3+ /2.0%Ho3+/12.0%Ce3+ nanocrystals and (b)−(e) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4:x%Yb3+(x = 0%, 5.0%, 10.0%, 15.0%) core-shell nanocrystals.
图 2 (a) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+纳米晶体和NaLuF4:20.0%Yb3+/2.0%Ho3+/12%Ce3+@ NaLuF4:x%Yb3+((b) 0, (c) 5.0%, (d)10.0%, (e) 15.0%)纳米核壳结构的TEM图谱
Figure 2. TEM images and EDX spectra of (a) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+ nanocrystals and (b)−(e) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4: x%Yb3+ (x = 0, 5.0%, 10.0%, 15.0%) core-shell nanocrystals.
图 3 在980 nm激发下, (a) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+和(b)−(e) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4:x%Yb3+ (x = 0%, 5.0%, 8.0%,10.0%, 12.0%, 15.0%)纳米晶体及核壳结构的上转换发射光谱(A)、增强因子(B)和红绿比(C)
Figure 3. The upconverison emission spectra (A), enhancement factor (B) and red andgreen emission intensity ratio (R/G) (C) of (a) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+ nanocrystals and (b)−(e) NaLuF4:20.0%Yb3+/2.0%Ho3+/12%Ce3+@ NaLuF4:x%Yb3+ (x = 0%, 5.0%, 8.0%, 10.0%, 12.0%,15.0%) core-shell nanocrystals under 980 nm excitation.
图 4 (a) NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+以及(b)—(e)NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@NaLuF4:x%Yb3+ (x = 0%, 5.0%, 10.0%, 15.0%) 纳米晶体及核壳结构的色度坐标图
Figure 4. The CIE diagram with position of color coordinates of Ho3+ in (a) NaLuF4 nanocrystals and (b)-(e) NaLuF4@ NaLuF4:x%Yb3+ (x = 0%, 5.0%, 10.0%, 15.0%) core-shell nanocrystals.
表 1 NaLuF4和NaLuF4@NaLuF4核壳纳米晶体的的CIE色坐标
Table 1. The calculated CIE chromaticity coordinates (x, y) of Ho3+ in NaLuF4 nanocrystals and NaLuF4@ NaLuF4:x%Yb3+ (x = 0%, 5.0%, 10.0%, 15.0%) core-shell nanocrystals.
Samples CIE chromaticity coordinates x y a (NaLuF4:20.0%Yb3+/2.0%Ho3+ /12.0%Ce3+) 0.5501 0.3891 b (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4) 0.5621 0.3786 c (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4: 5.0%Yb3+) 0.5643 0.3727 d (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4: 10.0%Yb3+) 0.5724 0.3692 e (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4: 15.0%Yb3+) 0.5756 0.3599 表 2 NaLuF4和NaLuF4@ NaLuF4核壳纳米晶体的红光发射的荧光寿命
Table 2. Luminescence lifetimes of NaLuF4 and NaLuF4@NaLuF4 core-shell nanocrystals under 980 nm excitation at 650 nm
Samples Lifetime/μs 650 nm a (NaLuF4:20.0%Yb3+/2.0%Ho3+ 12.0%Ce3+) 97.4 ± 0.2 b (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4) 125.4 ± 1.1 c (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4:5.0%Yb3+) 136.3 ± 0.8 d (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4:10.0%Yb3+) 184.2 ± 0.6 e (NaLuF4:20.0%Yb3+/2.0%Ho3+/12.0%Ce3+@ NaLuF4:15.0%Yb3+) 144.4 ± 0.4 -
[1] Menyuk N, Dwight K, Pinaud F 1972 Appl. Phys. Lett. 21 159Google Scholar
[2] Downing E, Hesselink L, Ralston J, Macfarlane R A 1996 Science 273 1185Google Scholar
[3] Zhang Y, Zhang L, Deng R, Tian J, Zong Y, Jin D, Liu X G 2014 J. Am. Chem. Soc. 136 4893Google Scholar
[4] Zou W, Visser C, Maduro J A, Pshenichnikov M S, Hummelen J C 2012 Nat. Photon. 6 560Google Scholar
[5] Su Q, Feng W, Yang D, Li F 2017 Acc. Chem. Res. 50 32Google Scholar
[6] Huang B L, Dong H, Wong K L, Sun L D, Yan C H 2016 J. Phys. Chem. C 120 18858Google Scholar
[7] Niu N, Yang P P, He F, Zhang X, Gai S L, Li C X, Lin J 2012 J. Mater. Chem. 2 2
[8] 高当丽, 郑海荣, 田宇, 雷瑜, 崔敏, 何恩节, 张喜生 2010 中国科学: 物理学 力学 天文学 40 287
Gao D L, Zheng H R, Tian Y, Lei Y, Cui M, He E J, Zhang X S 2010 Sci. Sin.: Phys. Mech. Astron. 40 287
[9] Gao W, Zheng H R, He E J, Lu Y, Gao F Q 2014 J. Lumin. 152 44Google Scholar
[10] Teng X, Zhu Y H, Wei W, Wang S C, Huang J F, Naccache R, Hu W B, Tok A I Y, Han Y, Zhang Q C, Fan Q L, Huang W, Capobianco J A, Huang L 2012 J. Am. Chem. Soc. 134 8340Google Scholar
[11] Heer S, Kompe K, Gudel H U, Haase M 2004 Adv. Mater. 16 2102Google Scholar
[12] Mai H X, Zhang Y W, Sun L D, Yan C H 2007 J. Phys. Chem. C 111 13721Google Scholar
[13] Shi F, Wang J S, Zhai X S, Zhao D, Qin W P 2011 Cryst. Eng. Comm. 13 3782Google Scholar
[14] Yang T S, Sun Y, Liu Q, Feng W, Yang P Y, Li F Y 2012 Biomaterials 33 3733Google Scholar
[15] He E J, Zheng H R, Gao W, Tu Y X, Lu Y, Li G A 2013 Mater. Res. Bull. 48 3505Google Scholar
[16] Chang J, Liu Y, Li J, Wu S L, Niu W B, Zhang S F 2013 J. Mater. Chem. C 1 1168Google Scholar
[17] Gao D L, Zhang X Z, Zheng H R, Gao W, He E J 2013 J. Alloy. Compd. 554 395Google Scholar
[18] Gao W, Zheng H R, Han Q Y, He E J, Gao F Q, Wang R B 2014 J. Mater. Chem. C 2 5327Google Scholar
[19] 何恩节, 郑海荣, 高伟, 鹿盈, 李俊娜, 魏映, 王灯, 朱刚强 2013 62 237803Google Scholar
He E J, Zheng H R, Gao W, Lu Y, Li J N, Wei Y, Wang D, Zhu G Q 2013 Acta Phys. Sin. 62 237803Google Scholar
[20] Dong J, Gao W, Han Q Y, Wang Y K, Qi J X, Yan X W, Sun M T 2019 Rev. Phys. 4 100026Google Scholar
[21] Dong J, Zhang Z L, Zheng H R, Sun M T 2015 Nanophotonics 4 472
[22] Li Y, Wang G F, Pan K, Fan N Y, Liu S, Feng L 2013 RSC Adv. 3 1683Google Scholar
[23] Rai M, Singh S K, Singh A K, Prasad R, Koch B, Mishra K, Rai S B 2015 ACS Appl. Mater. Inter. 7 15339Google Scholar
[24] Zuo J, Li Q Q, Xue B, Li C X, Chang Y L, Zhang Y L, Liu X M, Tu L P, Zhang H, Kong X G 2017 Nanoscale 9 7941Google Scholar
[25] Yi G S, Lu H C, Zhao S Y, Ge Y, Yang W J, Chen D P, Guo L H 2004 Nano Lett. 4 2191Google Scholar
[26] Chen X, Peng D, Ju Q, Wang F 2015 Chem. Soc. Rev. 44 1318Google Scholar
[27] Gao W, Dong J, Liu J H, Yan X W 2016 Mater. Res. Bull. 80 256Google Scholar
[28] 高伟, 董军 2017 66 204206Google Scholar
Gao W, Dong J 2017 Acta Phys. Sin. 66 204206Google Scholar
[29] Hu H, Chen Z G, Cao T Y, Zhang Q, Yu M G, Li F Y, Yi T, Huang C H 2008 Nanotechnology 19 375702Google Scholar
[30] Sangeetha N M, van Veggel F C J M 2009 J. Phys. Chem. C 113 14702Google Scholar
[31] Ye S, Chen G Y, Shao W, Junle Q, Paras N P 2015 Nanoscale 7 3976Google Scholar
[32] Xie X G, Ga N G, Deng R R, Sun Q, Xu Q H, Liu X G 2013 J. Am. Chem. Soc. 135 12608Google Scholar
[33] Wang F, Deng R R, Wang J, Wang Q X, Han Y, Zhu H M, Chen X Y, Liu X G 2011 Nat. Mater. 10 968Google Scholar
[34] Vetrone B F, Naccache R, MahalingamV, Morgan C G, Capobianco J A 2009 Adv. Funct. Mater. 19 2924Google Scholar
[35] Gao W, Kong X Q, Han Q Y, Dong J, Zhang W W, Zhang B, Yan X W, Zhang Z L, He E J, Zheng H R 2018 J. Lumin. 196 186
[36] Dong J, Zhang J, Han Q Y, Zhao X, Yan X W, Liu J H, Ge H B, Gao W 2019 J. Lumin. 207 361Google Scholar
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