| abstract |
Upconversion luminescent materials and method of preparation thereof. # The present invention relates to nanoparticles of formula MLnF {sub, 4}: RE {sup, + 3}, where M is an alkali metal, Ln is a lanthanide element or an analogue thereof and RE {sup, + 3} is a rare earth ion or combinations thereof; characterized in that said nanoparticles comprise organic ligands attached to their surface by covalent bonds. The invention also relates to a method of preparing the upconversion luminescent nanoparticles of the invention, the use of the upconversion luminescent nanoparticles of the invention as fluorescent or photosensitizer markers and a luminescent composite material comprising the upconversion luminescent nanoparticles of the invention. invention. |