Magnetic and optical properties of NaGdF4:Nd^3+, Yb^3+, Tm^3+ nanocrystals with upconversion/downconversion luminescence from visible to the near-infrared second window
We have designed and synthesized NaGdF4:Nd^3+, Yb^3+, Tm^3+. magnetic nano- phosphors with combined dual-mode downconversion (DC) and upconversion (UC) photoluminescence upon 800 run excitation. Hexagonal-phase NaGdF4:Nd^3+, Yb^3+, Tm^3+ nanocrystals (NCs) with an average size of 21 nm were synthesi...
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Veröffentlicht in: | 纳米研究:英文版 2015 (2), p.636-648 |
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Sprache: | eng |
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Zusammenfassung: | We have designed and synthesized NaGdF4:Nd^3+, Yb^3+, Tm^3+. magnetic nano- phosphors with combined dual-mode downconversion (DC) and upconversion (UC) photoluminescence upon 800 run excitation. Hexagonal-phase NaGdF4:Nd^3+, Yb^3+, Tm^3+ nanocrystals (NCs) with an average size of 21 nm were synthesized using a solvothermal approach. Nd^3+, Yb^3+, Tm^3+ triple-doped NaGdF4 NCs exhibit a broad range of photoluminescence peaks covering a near infrared first/second window (860-900, 1,000, and 1,060 nm), and visible emission including blue (475 nm), green (520 and 542 nm) and yellow (587 nm) after excitation at 800 nm. A mechanism involving circulation of energy over Gd^3+ sublattices as bridge ions and final trapping by the initial activator ions (Nd^3+) has been proposed. Penetration depth studies indicate that NIR emission is easily detected even at a large tissue thickness of 10 mm. These paramagnetic nanophosphors demonstrate a large magnetization value of 1.88 emu/g at 20 kOe and longitudinal relaxivity value of 1.2537 mM-1.S-1 as a Tl-weighted magnetic resonance imaging contrast agent. These NaGdF4:Nd^3+, Yb^3+ Tm^3+ NCs are promising for applications in biological and magnetic resonance imaging. |
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ISSN: | 1998-0124 1998-0000 |