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

We study concentration quenching and energy transfer mechanisms of yttrium oxide (YO) 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 YO sample. The doping of Ce in YO 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 YO is shorter than that of the undoped YO 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 YO to the Ce ion centres. The critical quenching concentration of Ce ion in YO: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.