Thin-walled Er3+:Y2O3 nanotubes showing up-converted fluorescence.

Up-converted red and green fluorescence has been measured in low-crystallinity Er3+:Y2O3 nanotubes upon IR excitation. A new preparation procedure for thin-walled erbium doped yttria nanotubes using alumina templates as shape defining tools and rare earth nitrates as precursors for a purely thermolytic production of erbium doped yttria was developed. The products with a diameter of approximately 40-50 nm and a wall thickness of only 6-8 nm showed up-converted fluorescence with green and red emission bands when excited at 815 nm. The fluorescence properties are compared to the ones of bulk erbium-doped yttria obtained from the same precursor system.