White light upconversion of nanocrystalline Er/Tm/Yb doped tetragonal Gd4O3F6

Er3+, Tm3+ and Yb3+ codoped gadolinium oxyfluoride nanoparticles were prepared in aqueous solution by a simple coprecipitation method, under alkaline conditions. After a suitable heat treatment at 500 °C, the nanocrystalline powders were found to be single phase tetragonal Gd4O3F6 after a structural characterization using X-ray powder diffraction. Transmission electron microscopy images showed that the average size of the nanoparticles was approximately 50 nm. Following appropriate lanthanide ion doping, the nanocrystals show bright white light upconversion upon excitation at 980 nm using a diode laser as the excitation source.

Research highlights
► Lanthanide doped, single phase tetragonal Gd4O3F6 nanoparticles (average size around 50 nm) have been prepared by a coprecipitation method.
► Bright white light upconversion has been observed, upon 980 laser excitation, for the Er3+, Tm3+ and Yb3+ codoped Gd4O3F6 nanoparticles
► Er3+, Tm3+ and Yb3+ codoped Gd4O3F6 nanoparticles are prepared by coprecipitation.
► The average particle size is around 50 nm.
► Bright white light upconversion is observed upon 980 laser excitation.