NIR-to-visible and NIR-to-NIR upconversion in lanthanide doped nanocrystalline GdOF with trigonal structure

Codoped Er(3+)/Yb(3+), Tm(3+)/Yb(3+), Ho(3+)/Yb(3+) and triply doped Er(3+)/Tm(3+)/Yb(3+) gadolinium oxyfluoride nanoparticles were prepared in aqueous solution by a simple coprecipitation method and a suitable heat treatment at 500 degrees C. From the experimental X-Ray powder diffraction patterns, a Rietveld analysis was carried out and it was determined that the nanoparticles are single phase trigonal GdOF. Electron microscopy images show that the average particle size is approximately 25 nm, even though a certain degree of agglomeration is evidenced. The spectroscopic properties of the lanthanide doped nanoparticles are investigated in terms of emission spectra. For proper lanthanide concentrations, the nanoparticles show visible upconversion upon excitation at 980 nm, making them useful as luminescent nanomaterials for photonic applications.