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Updated: Jan 21, 2026
13:51
Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications
Published on: November 10, 2017
15.8K
Imaging dopant distribution across complete phase transformation by TEM and upconversion emission
Daniel Avram1, Claudiu Colbea, Mihaela Florea
1National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, RO 76900, Bucharest-Magurele, Romania. carmen.tiseanu@inflpr.ro.
Nanoscale
|August 13, 2019
Summary
Understanding dopant distribution in nanomaterials is key. This study reveals how subtle changes in erbium (Er) distribution within zirconium dioxide (ZrO2) nanoparticles significantly alter their upconversion (UPC) optical properties.
Area of Science:
- Nanomaterials Science
- Solid-State Chemistry
- Optical Spectroscopy
Background:
- Correlating dopant distribution with optical properties in nanomaterials is challenging.
- Distinguishing true dopant clustering from statistical distribution is crucial for understanding doping-functionality relationships.
- Lanthanide dopant distribution, including enrichment, depletion, and surface segregation, impacts optical responses.
Purpose of the Study:
- To associate lanthanide dopant distribution with optical response in upconversion (UPC) at both ensemble and single-nanoparticle levels.
- To investigate the effect of minor deviations in erbium (Er) concentration on Er-doped ZrO2 nanoparticles' UPC properties.
- To explore the relationship between dopant distribution, phase transformation, and UPC mechanisms.
Main Methods:
- Synthesis of rationally designed Er-doped ZrO2 nanoparticles.
- Characterization using Z- and phase contrast transmission electron microscopy (TEM).
- Optical response analysis including upconversion (UPC) emission, intensity, and excited-state dynamics at ensemble and single-nanoparticle levels.
Main Results:
- A small deviation in Er concentration induced significant differences in UPC emission color, intensity, and dynamics.
- Heterogeneous dopant distribution leading to coexisting tetragonal and monoclinic phases within a single nanoparticle was observed.
- Spectroscopic isolation of Er in different phases was confirmed, with no energy transfer between them.
- Upconversion (UPC) revealed minor phases overlooked by X-ray diffraction and TEM, highlighting segregated Er's absence in UPC signals.
Conclusions:
- Combined TEM and UPC emission are highly sensitive to subtle deviations from uniform doping, even at low concentrations.
- The study demonstrates the critical role of dopant distribution in dictating optical functionalities of doped nanomaterials.
- This approach is valuable for studying functional oxides with lanthanide dopants as emitters.
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