Synthesis of Tributylphosphate Capped Luminescent Rare Earth Phosphate Nanocrystals in an Ionic Liquid Microemulsion

Uniform rare earth phosphate (REPO 4, RE = La−Tb) nanocrystals were successfully synthesized in a properly designed TBP/[Omim]Cl/H 2 O (tributylphosphate/1-octyl-3-methyl-imidazolium chloride/water) microemulsion system. The phosphoryl groups anchored the TBP molecules on the surfaces of the nanocrystals, and this made the nanocrystals easily dispersed in some imidazolium-based ILs. LaPO 4:Eu 3+ and CePO 4:Tb 3+ nanocrystals capped with TBP showed bright red and green emission under UV excitation, with enhanced emission intensity and lifetimes compared with the uncapped ones. [Omim]Cl and TBP were found to play the key roles in the nucleation and growth of the nanocrystals. The designed strategy provided a facile way for the fabrication of TBP capped REPO 4 nanocrystals, which may also be applicable for the synthesis of other inorganic nanocrystals.