Multicolour synthesis in lanthanide-doped nanocrystals through cation exchange in water
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A quick, efficient method to tune the colour of light emitted by luminescent nanocrystals has been developed by a team that includes Nanjing Tech University researchers.
The team used nanocrystals of sodium gadolinium fluoride, 17 nanometres across, seasoned with a dash of metallic elements such as cerium, ytterbium or thulium. They then replaced some of these elements in the nanocrystal’s outer shell with various ‘activator’ metal ions, each chosen to produce a specific colour.
When infra-red or ultraviolet light shines on the nanoparticles, the metallic elements in the core harvest the energy and pass it via a chain of gadolinium ions to the outer shell. This cascade of energy excites the activator ions, causing them to emit visible light of a specific colour. In one example, a manganese activator produced a green luminescence that lasted for a record-breaking 600 milliseconds.
This method will help researchers tailor luminescent nanocrystals for diverse applications, including biological imaging.
- Nature Communications 7,13059 (2016). doi: 10.1038/ncomms13059