Broadband white emission from Yb3+ doped Sr2CeO4 nanocrystals

Intense broadband anti-Stokes white emission (BASWE) generated from Sr2CeO4:Yb3+ nanocrystals in vacuum upon focused infrared excitation lines (808 and 975 nm) is reported. The samples were prepared via Pechini's technique. The crystal structures of the phosphors were confirmed by X-ray diffraction data measurements. Based on them the average crystallite sizes of the samples were determined by Rietveld refinement to be 72 and 41 nm for 1 and 20% of dopant concentration, respectively. In particular the emission intensity in function of power density and surroundings pressure were investigated. It was found that the emission intensity increases significantly with increasing power excitation for excitation lines. It is also interesting to see that the pressure dependence for both excitation lines are similar. Results of these two measurements exhibit threshold behavior which is characteristic for the avalanche effect. The rise times dependence in function of excitation power were also studied.