Localization induced intense red upconversion luminescence in monodispersed K3ZrF7:Yb3+/Er3+ nanocrystals

Luo, Wenqin; Wu, Haiyan; Li, Bin

doi:10.1016/j.cplett.2016.06.041

Cited by 7 publications

(4 citation statements)

References 23 publications

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“…Owing to the high-symmetry crystal lattice of the K 3 ZrF 7 host matrix (Figure a,b), the UCL red-to-green (R/G) intensity ratio was calculated to be as high as ∼51.4, thereby yielding a bright-red color output with excellent photostability and thermal stability (Figure h and Figures S4 and S5). This observation stands in stark contrast to the typical olive UCL observed from the Yb 3+ /Er 3+ (20/2 mol %)-doped β-NaYF 4 UCNCs (Figures g and S4) or previously reported K 3 ZrF 7 :Yb/Er UCNCs with comparable red and green emission bands. The overall intensity for the red UCL of Er 3+ in the as-synthesized K 3 ZrF 7 :Yb/Er UCNCs was determined to be about 1/15 that of their β-NaYF 4 :Yb/Er counterparts, with a nearly identical nanocrystal size of ∼28 nm (Figure S6).…”

Section: Results and Discussioncontrasting

confidence: 99%

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications

Peng

et al. 2020

ACS Nano

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Lanthanide-doped inorganic upconversion nanocrystals (UCNCs) are promising as fluorescent diagnostic and therapeutic agents for in vivo applications ranging from biological imaging to disease theranostics. However, all currently available lanthanide-doped inorganic UCNCs are not biodegradable and thus cannot be harmlessly eliminated from the body of living organism during a reasonable period of time, making their clinical translations nearly impossible. Here, we report a class of redemitting biodegradable UCNCs based on Yb 3+ /Er 3+ -doped inorganic potassium heptafluozirconate (K 3 ZrF 7 :Yb/Er) that features a dynamically "soft" crystal lattice containing watersoluble [ZrF 7 ] 3− cluster and a K + cation. The red-emitting K 3 ZrF 7 :Yb/Er UCNCs exhibit a pH-dependent biodegradation capability upon exposure to water both in vitro and in vivo, and the rapid biodegradation rate, monitored using the intrinsic red upconversion luminescence, can be tuned particularly in a mild acidic tumor microenvironment (pH ∼5−6). More importantly, the final biodegradation products of K 3 ZrF 7 :Yb/Er UCNCs can be excreted from the body of mice in a short period of time with no evidence of toxicity, in stark contrast to the nondegradable β-NaYF 4 :Yb/Er UCNCs that primarily accumulate in the main organs of mice. These findings described here unambiguously would benefit the future biomedical applications and clinical translations of lanthanide-doped inorganic UCNCs.

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Section: Results and Discussioncontrasting

confidence: 99%

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications

Peng

et al. 2020

ACS Nano

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“…In order to understand the UC mechanisms, as an example, the dependences of green (522 and 542 nm) and red (652 nm) emissions intensities of Na 0.5 Li 0.5 ReF 4 microcrystal on pump power were measured, as shown in Figure . For the unsaturated UC process, the number of photons required to populate the upper emitting level can be described by the following relation: where I is the upconversion emission intensity, P refers to the pump laser intensity, and n represents the number of photons required in the UC process. , As shown in Figure , the slope value corresponding to 522 nm, 542 nm, and 652 nm emissions of Na 0.5 Li 0.5 ReF 4 microcrystal are 1.84, 1.79, and 1.76, respectively. These results indicate both the green (522 and 542 nm) and red emissions (652 nm) emission bands of Er 3+ are two-photon process in Na (1‑ x ) Li x ReF 4 microcrystals (the relative energy level of Yb 3+ and Er 3+ ions and their corresponding pathways in the UC process under the excitation of 980 nm near-infrared laser are shown in Figure )…”

Section: Resultsmentioning

confidence: 99%

“…For the unsaturated UC process, the number of photons required to populate the upper emitting level can be described by the following relation: 59 where I is the upconversion emission intensity, P refers to the pump laser intensity, and n represents the number of photons required in the UC process. 59,60 As shown in Figure 7, the slope value corresponding to 522 nm, 542 nm, and 652 nm emissions of Na 0.5 Li 0.5 ReF 4 microcrystal are 1.84, 1.79, and 1.76, respectively. These results indicate both the green (522 and 542 nm) and red emissions (652 nm) emission bands of Er 3+ are two-photon process in Na (1-x) Li x ReF 4 microcrystals (the relative energy level of Yb 3+ and Er 3+ ions and their corresponding pathways in the UC process under the excitation of 980 nm near-infrared laser are shown in Figure 8) Figure 8 indicates the simplified energy level diagrams of Yb 3+ and Er 3+ as well as the proposed possible UC mechanism in Na (1-x) Li x ReF 4 microcrystals.…”

Section: Crystal Growth and Designmentioning

confidence: 94%

Na_(1-x)Li_x(Gd_0.39Y_0.39Yb_0.2Er_0.02)F₄ (0 ≤ x ≤ 1) Solid Solution Microcrystals: Li/Na Ratio-Induced Transition of Crystalline Phase and Morphology and Their Enhanced Upconversion Emission

Luo

Chen

et al. 2018

Crystal Growth & Design

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Na (1-x) Li x (Gd 0.39 Y 0.39 Yb 0.2 Er 0.02 )F 4 (0 ≤ x ≤ 1) (denoted as Na (1-x) Li x ReF 4 ) solid solution microcrystals with different microstructures have been synthesized by a facile hydrothermal method. The influences of Li + ion concentration on the morphology, crystal structure, grain size, and upconversion emission of the microcrystals are deeply investigated. It is found that the substitution concentration of Li + not only causes the phase transition but also induces variation in morphology and size. When the substitution concentration of Li + ions is lower (x ≤ 0.3), the obtained Na (1-x) Li x ReF 4 microcrystals possess hexagonal structure and exhibit hexagonal prism in morphology. Whereas at the higher substitution concentration of Li + ions (x ≥ 0.6), the crystalline phase of the final Na (1-x) Li x ReF 4 microcrystals transformed into tetragonal structure and their morphology changed into octahedron except for the sample Na (1-x) Li x ReF 4 with x = 0.9. Predictably, the obtained Na (1-x) Li x ReF 4 microcrystals at the moderate substitution concentration of Li + ions (x = 0.4 and 0.5) own the coexistent phases of hexagonal and tetragonal and display the obvious symbiotic morphologies of hexagonal prism and octahedron. All the samples showed characteristic emission peaks in green and red region with center wavelengths at 522 nm, 542 nm, and 652 nm respectively, and their upconversion intensities initially lift and then drop with the increasing x, giving the maximum at x = 0.5. Specifically, for the codoped Na 0.5 Li 0.5 ReF 4 microcrystal, its UC intensity of the strongest green emission at 542 nm is about 18 times and 73 times greater than that of the codoped NaReF 4 and LiReF 4 microcrystals, respectively. Moreover, the variation amplitude of intensity for the green emission bands is much greater than that of the red emission with the increasing x. It could obtain a superior host matrix for upconversion luminescence by means of the formation of Na (1-x) Li x ReF 4 solid solution at the feasible substitution concentration of Li + (0.2 < x ≤ 0.6).

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“…Recently, rare-earth (RE)-doped luminescent materials have received extensive attention for their potential applications such as high-resolution displays, phosphors, solid-state lasers, scintillators, communication fibres, optical storage, solar cells and biological fields [1][2][3][4][5][6][7]. Among them, upconversion (UC) luminescence from the near-infrared (NIR) region to the visible region, which can convert from lower energy to higher energy radiation through multiple absorption or energy transfer, has been actively studied [8,9].…”

Section: Introductionmentioning

confidence: 99%

Microwave hydrothermal synthesis and upconversion luminescence properties of $$\hbox {Yb}^{3+}$$ Yb 3 + / $$\hbox {Tm}^{3+}$$

2017

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Tetragonal NaY(MoO 4) 2 (NYM) phosphors co-doped with Yb 3+ and Tm 3+ ions were synthesized through microwave hydrothermal method followed by calcining treatment. Powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and photoluminescence spectra were used to characterize the properties of asprepared samples. The results show that Yb 3+ /Tm 3+ co-doped NYM displayed bright blue emission near 472 and 476 nm (1 G 4 → 3 H 6 transition), strong near-infrared upconversion (UC) emission around 795 nm (3 H 4 → 3 H 6 transition). The optimum doping concentrations of Yb 3+ and Tm 3+ for the most intense UC luminescence were obtained, and the related UC mechanism of Yb 3+ /Tm 3+ co-doped NYM depending on pump power was studied in detail.

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Localization induced intense red upconversion luminescence in monodispersed K3ZrF7:Yb3+/Er3+ nanocrystals

Cited by 7 publications

References 23 publications

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications

Na_(1-x)Li_x(Gd_0.39Y_0.39Yb_0.2Er_0.02)F₄ (0 ≤ x ≤ 1) Solid Solution Microcrystals: Li/Na Ratio-Induced Transition of Crystalline Phase and Morphology and Their Enhanced Upconversion Emission

Microwave hydrothermal synthesis and upconversion luminescence properties of $$\hbox {Yb}^{3+}$$ Yb 3 + / $$\hbox {Tm}^{3+}$$

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Localization induced intense red upconversion luminescence in monodispersed K3ZrF7:Yb3+/Er3+ nanocrystals

Cited by 7 publications

References 23 publications

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications

Na(1-x)Lix(Gd0.39Y0.39Yb0.2Er0.02)F4 (0 ≤ x ≤ 1) Solid Solution Microcrystals: Li/Na Ratio-Induced Transition of Crystalline Phase and Morphology and Their Enhanced Upconversion Emission

Microwave hydrothermal synthesis and upconversion luminescence properties of $$\hbox {Yb}^{3+}$$ Yb 3 + / $$\hbox {Tm}^{3+}$$

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Na_(1-x)Li_x(Gd_0.39Y_0.39Yb_0.2Er_0.02)F₄ (0 ≤ x ≤ 1) Solid Solution Microcrystals: Li/Na Ratio-Induced Transition of Crystalline Phase and Morphology and Their Enhanced Upconversion Emission