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Watching Nanocrystals Grow: Real Time, Spectroscopic Monitoring of NaYF4: Yb, Er Upconverting Nanocrystal (UCNC) Synthesis John D. Suter II, Cuikin Lin, Bo Zhao, Mary Berry, P. Stanley May Department of Chemistry, University of South Dakota; Vermillion, South Dakota, 57069 Potential Applications
Background and Introduction
● Bio-imaging ● Security Printing ● Energy Conversion...
Initial Results Crystal Size vs. Reaction temperature
T < 310°C
Rat with UCNCs injected below skin Quick response code under under NIR irradiation. Quantum dot NIR irradiation made by UCNC luminescence was unable to be seen containing inks. Blumenthal, T, . et. al. Nanotechnology, 23, 2012, 185305 (8pp)
NaYF4:Yb,Er UC Mechanism Yb3+ donor
(absorbing species)
Absorbs 980nm light Very long lifetime (~1 ms) Can undergo energy transfer with a neighboring Er3+
Crystal Size vs. Reaction Time
2H 4I 11/2 15/2 2S 4I 3/2 15/2
T = 310°C
Small (< 10nm) UCNCs α-phase
D. K. Chatterjee, A. J. Rufaihah and Y. Zhang, Biomaterials , 2008, 29 , 937
Crystal Size & Size Distribution
Real Time Monitoring
Two results Large (30-40 nm) UCNCs • β-phase Bimodal distribution T > 310°C Very Large (100-250 nm) UCNCs Very small UCNCs • Small UCNCs β-phase • Mix of α-phase and β-phase
Crystal size and size distributions were measured on samples taken out at various points in the reaction.
0% 4F
0
4I 9/2 15/2
• What is going on at 310°C? • How can we increase our reproducibility? • Can we better understand the crystal growth mechanism?
2H 9/2 4I15/2
0% 0
TEM image before rapid rise: Small α-phase UCNCs
During rapid rise (18.5 min)
0
5
10 15 20 25 30 35 40 45 Long Diameter (nm)
30%
During rapid rise (12.2 min)
0% 0
1) Remove MeOH 2) Heat under Argon
β-NaYF4: Yb, Er
Before rapid rise: Small Nanocrystal
α-NaYF
β-NaYF
1.) H.-S. Qian and Y. Zhang, Langmuir, 24, 2008, 12123
Real Time Monitoring Set-Up B) Focusing Mirror E) Fiber Optic Collector
C) Reaction Flask
10
20
30
40 50 Degrees (2θ)
60
70
5
10 15 20 25 30 35 40 45 Long Diameter (nm)
30%
Before rapid rise (8.6 min)
0% 0
5
10 15 20 25 30 35 40 45 Long Diameter (nm)
Average UCNC size at various points in the synthesis 40
Average UCNC size
Procedure1
• Solution was heated to a specific temperature (300-320°C) and held for 1 hr. • Trying to make β-phase NaYF4 Nanocrystals with diameters
Background and Introduction
● Bio-imaging ● Security Printing ● Energy Conversion...
Initial Results Crystal Size vs. Reaction temperature
T < 310°C
Rat with UCNCs injected below skin Quick response code under under NIR irradiation. Quantum dot NIR irradiation made by UCNC luminescence was unable to be seen containing inks. Blumenthal, T, . et. al. Nanotechnology, 23, 2012, 185305 (8pp)
NaYF4:Yb,Er UC Mechanism Yb3+ donor
(absorbing species)
Absorbs 980nm light Very long lifetime (~1 ms) Can undergo energy transfer with a neighboring Er3+
Crystal Size vs. Reaction Time
2H 4I 11/2 15/2 2S 4I 3/2 15/2
T = 310°C
Small (< 10nm) UCNCs α-phase
D. K. Chatterjee, A. J. Rufaihah and Y. Zhang, Biomaterials , 2008, 29 , 937
Crystal Size & Size Distribution
Real Time Monitoring
Two results Large (30-40 nm) UCNCs • β-phase Bimodal distribution T > 310°C Very Large (100-250 nm) UCNCs Very small UCNCs • Small UCNCs β-phase • Mix of α-phase and β-phase
Crystal size and size distributions were measured on samples taken out at various points in the reaction.
0% 4F
0
4I 9/2 15/2
• What is going on at 310°C? • How can we increase our reproducibility? • Can we better understand the crystal growth mechanism?
2H 9/2 4I15/2
0% 0
TEM image before rapid rise: Small α-phase UCNCs
During rapid rise (18.5 min)
0
5
10 15 20 25 30 35 40 45 Long Diameter (nm)
30%
During rapid rise (12.2 min)
0% 0
1) Remove MeOH 2) Heat under Argon
β-NaYF4: Yb, Er
Before rapid rise: Small Nanocrystal
α-NaYF
β-NaYF
1.) H.-S. Qian and Y. Zhang, Langmuir, 24, 2008, 12123
Real Time Monitoring Set-Up B) Focusing Mirror E) Fiber Optic Collector
C) Reaction Flask
10
20
30
40 50 Degrees (2θ)
60
70
5
10 15 20 25 30 35 40 45 Long Diameter (nm)
30%
Before rapid rise (8.6 min)
0% 0
5
10 15 20 25 30 35 40 45 Long Diameter (nm)
Average UCNC size at various points in the synthesis 40
Average UCNC size
Procedure1
• Solution was heated to a specific temperature (300-320°C) and held for 1 hr. • Trying to make β-phase NaYF4 Nanocrystals with diameters
