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Tuning epitaxial growth on NaYbF4 upconversion nanoparticles by strain management
Jianxiong Zhao1, Bing Chen, Xian Chen
1Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong SAR, China. fwang24@cityu.edu.hk.
Nanoscale
|June 25, 2020
Summary
Controlling core-shell nanoparticle growth with specific rod-like shapes and reaction temperatures improves upconversion luminescence. This enables enhanced magnetic resonance imaging contrast agents for advanced applications.
Area of Science:
- Materials Science
- Nanotechnology
- Luminescence
Background:
- Core-shell nanostructures are crucial for tuning upconversion luminescence in lanthanide-doped nanoparticles.
- Epitaxial growth on hexagonal NaYbF4 nanoparticles is challenging due to interfacial strain, leading to incomplete shell coverage.
Purpose of the Study:
- To investigate how core particle size, morphology, and reaction temperature influence the epitaxial growth of NaGdF4 shells on NaYbF4 nanoparticles.
- To develop strategies for achieving high surface coverage in core-shell nanostructures.
Main Methods:
- Exploration of core particle size and morphology effects on shell growth.
- Optimization of reaction temperature for controlled epitaxial growth.
- Utilizing NaGdF4 as a transition layer for subsequent NaNdF4 coating.
Main Results:
- Rod-like core particles with larger dimensions promote shell growth with high surface coverage by relaxing lattice strains.
- The NaGdF4 shell effectively mediates the growth of NaNdF4 layers, accommodating larger lattice misfits.
- The resulting NaYbF4@Na(Gd/Nd)F4 core-shell nanostructures exhibit enhanced multiphoton upconversion luminescence and T1 ionic relaxivity.
Conclusions:
- Rational design of core-shell nanostructures, particularly using specific core morphologies and transition layers, is key to optimizing properties.
- The developed NaYbF4@Na(Gd/Nd)F4 nanostructures show promise for applications requiring strong upconversion luminescence and magnetic resonance imaging capabilities.
