Intense visible multicolored luminescence from lanthanide ion-pair codoped NaGdF₄ nanocrystals

Area of Science:

• Materials Science
• Nanotechnology
• Inorganic Chemistry

Background:

• Lanthanide-doped NaGdF4 nanocrystals are promising for optical applications due to their luminescence properties.
• Controlling the emission color and intensity is crucial for advanced photonic devices.
• Biocompatibility is essential for in vivo applications, requiring surface modification.

Purpose of the Study:

• To synthesize lanthanide ion-pair codoped NaGdF4 nanocrystals using cerium (Ce3+) as a sensitizer.
• To investigate the optical properties and tunability of these codoped nanocrystals.
• To enhance the biocompatibility of the nanocrystals through silica coating.

Main Methods:

• Polyol method for synthesizing NaGdF4 nanocrystals codoped with various lanthanide ion pairs (Eu3+/Tb3+, Dy3+/Tb3+, Sm3+/Tb3+, Eu3+/Dy3+) and sensitized by Ce3+.
• Single-wavelength excitation at 251 nm to observe combined spectra.
• UV lamp excitation at 254 nm for visible emission analysis.
• Silica (SiO2) coating for surface modification.

Main Results:

• The synthesized NaGdF4 nanocrystals exhibit distinct optical properties for different lanthanide ion-pair combinations.
• Combined spectra from codoped ions are observable with single-wavelength excitation.
• Tunable visible emissions in different colors were achieved by adjusting doping ion molar ratios.
• Silica coating successfully rendered the nanocrystals biocompatible.

Conclusions:

• Lanthanide ion-pair codoped NaGdF4 nanocrystals can be synthesized with tunable optical properties.
• The polyol method provides a viable route for creating these functional nanomaterials.
• SiO2 coating is an effective strategy to improve the biocompatibility of NaGdF4 nanocrystals for potential biomedical applications.