Photoluminescence profile imaging of Eu(III), Tb(III) and Eu(III)/Tb(III)-doped yttrium oxide nanosheets and nanorods

Eu(III), Tb(III) and Eu(III)/Tb(III)-doped Y2O3 nanosheets and nanorods were prepared by hydrothermal synthesis and post-thermal treatment. Their morphology, crystallinity, photoluminescence and UV-visible absorption profiles were fully examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) crystallography, photoluminescence imaging and UV-vis absorption spectroscopy. The as-prepared samples commonly showed the crystal structure of Y4O(OH)9NO3, which crystallized to cubic phase Y2O3 after 550 °C-thermal annealing. The sharp emissions of Eu(III) between 580 and 720 nm were attributed to 5D0→7FJ (J=0,1,2,3,4) transitions, and those of Tb(III) between 450 and 720 nm were attributed to 5D4→7FJ (J=6,5,4,3) transitions. Energy transfer from Tb(III) to Eu(III) was confirmed by the photoluminescence decay dynamics. In the cubic Y2O3 structure, Eu(III) was embedded at the C2 symmetry site and dominated by the 5D0→7F2 transition. Conversely, Tb(III) was oxidized to non-luminescent Tb(IV) in the cubic structure.