Study of Concentration Quenching and Energy Transfer Mechanism in Ce Doped Y2O3 Nanomaterials.

We study concentration quenching and energy transfer mechanisms of yttrium oxide (Y₂O₃) nanomaterials doped with different concentrations (0-5 mol%) of cerium (Ce). Photoluminescence (PL) spectra recorded under an excitation wavelength of 350 nm show a broad emission band at ∼ 406 nm and a feeble emission band at ∼ 463 nm in the undoped Y₂O₃ sample. The doping of Ce in Y₂O₃ induced multiple PL peaks within the blue-green region of the spectrum in all the doped samples with the peak at ∼ 466 nm being notably the prominent one. This prominent emission band exhibits a decrease in intensity with increasing Ce concentration due to concentration quenching. Analysis of Time-resolved photoluminescence (TRPL) spectra reveal that the average emission lifetime of Ce-doped Y₂O₃ is shorter than that of the undoped Y₂O₃ sample. The concentration quenching effect and the decrease of average emission lifetime of the dominant emission band are explained on the basis of energy transfer from the host Y₂O₃ to the Ce³⁺ ion centres. The critical quenching concentration of Ce³⁺ ion in Y₂O₃:Ce phosphor was identified to be 1 mol% and the critical transfer distance was estimated to be 23.74 Å. Analysis reveal that the concentration quenching mechanism involves nearest-neighbour interaction.