Influence of dopant concentration on spectroscopic properties of Sr2CeO4:Yb nanocrystals

Abstract Optical properties of Sr 2 CeO 4 :Yb nanocrystals synthesized via Pechini's method are reported. The samples were characterized by X-ray diffraction data measurements. The unit cell parameters were determined using Rietveld refinement. It was found that they decreased with increasing amount of Yb ions. The absorption, excitation, emission spectra and luminescence decay profiles of the Sr 2 CeO 4 :Yb nanocrystals were investigated. It was observed that optical properties were strongly dependent on Yb concentration. It was found that Yb 3+ -O 2- charge transfer transitions have great influence on the absorption spectra. It can be seen in the emission spectra that in addition to standard bands/lines corresponding to Ce-O metal-to-ligand charge transfer of Sr 2 CeO 4 and f-f transitions of Yb 3+ , there is emission band centered at 744 nm. Its intensity depends on the concentration of the dopant. Recorded decay times become shorter with increasing dopant concentration due to the Yb 3+ concentration quenching. Excitation spectra indicate the energy transfer from Ce-O charge transfer states to Yb 3+ 2 F 5/2 state. The issue of appearance of down-conversion process in Sr 2 CeO 4 :Yb nanocrystals is considered.