Energy transfer phenomena in Er3+, Yb3+, Tm3+ tri-doped lanthanum oxysulfide phosphors

Lanthanum oxysulfide (La 2 O 2 S) was investigated as an effective doping matrix for the development of Er 3+ , Yb 3+ , Tm 3+ tri-doped phosphors emitting white light. The powders were prepared by combustion synthesis and subsequently post-sulfurized under H 2 S/N 2 . They were characterized using Powder X-Ray Diffraction, Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscopy and thermogravimetric analysis to assess their purity, morphology and thermal stability. The excitation, down-conversion and up-conversion properties of the phosphors were then studied using UV/Visible/NIR and fluorescence spectroscopy. Although white emission was not achieved with the studied compositions, a mechanism for up-conversion energy transfer in the tri-doped samples is proposed. • Energy transfer phenomena in Er 3+ , Yb 3+ , Tm 3+ tri doped lanthanum oxysulfide phosphors. • Synthesis of high-purity, well crystalized and nanometric La 2 O 2 S tri-doped powders. • Complete study of up- and down-conversion properties of La 2 O 2 S phosphors. • Up-conversion mechanism proposition of tri-doped La 2 O 2 S phosphors.