Optical Characterization of Infrared Emitting Rare-Earth-Doped Fluoride Nanocrystals and Their Transparent Nanocomposites

Nanocrystalline LaF 3:Nd and CaF 2:Er with rare-earth concentrations ranging from 0.5 to 16.7 mol % and dispersible particle sizes less than 100 nm were synthesized by solvothermal synthesis. Optical absorption, emission, and quantum efficiency were measured for the nanocrystals. Dopant levels of 0.5 mol % rare earth exhibited the best emission characteristics, with maximum quantum efficiencies of 95 and 51% for LaF 3:Nd and CaF 2:Er, respectively. The nanopowders were suspended in PFCB (6F variant) polymer-in-toluene solutions to make transparent suspensions that could be cast to make transparent nanocomposites. Scattering analysis indicates that the excellent transmission can be attributed to nanocrystals dispersed in the composite at length scales less than 100 nm.