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

Codoped Er3+/Yb3+, Tm3+/Yb3+, Ho3+/Yb3+ and triply doped Er3+/Tm3+/Yb3+ gadolinium oxyfluoride nanoparticles were prepared in aqueous solution by a simple coprecipitation method and a suitable heat treatment at 500 °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.

► The color of the upconversion can be tuned with a proper choice and concentration of lanthanide ions. ► A trigonal GdOF structure has been found by Rietveld refinement of the XRPD patterns. ► Bright upconversion in the visible and near infrared range is observed upon excitation at 980 nm. ► The color of the upconversion emission can be tuned in the visible and near infrared with a proper choice of lanthanide ions and their concentration.