The upconversion photoluminescence of Ho(3+) ion sensitized by Yb(3+) ion in Ho(3+)/Yb(3+) codoped Gd(2)O(3) nanocrystals with and without Li(+) is investigated in this paper. Strong fluorescence in the green (534-570 nm) and red (635-674 nm) regions of the spectrum has been observed, arising from the (5)F(4)/(5)S(2) → (5)I(8) and (5)F(5) → (5)I(8) transitions of Ho(3+) ion, respectively. Yb(3+) ion is considered to be a better sensitizer for catching enough pumping energy and transferring considerable energy to Ho(3+) in the Ho(3+)/Yb(3+) system. The upconversion intensity emitted by Ho(3+) is greatly enhanced when Li(+) is added to the Ho(3+)/Yb(3+) codoped Gd(2)O(3) nanocrystals.
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