Red light from ZrO2:Eu3+ nanostructures

Zirconia nanocrystals doped with europium ions were developed envisaging optical applications. The nanostructures were produced using zirconyl nitrate (ZrO(NO3)2·H2O) and europium nitrate (Eu(NO3)3·5H2O) as cation precursors, and urea (C2H5NO2) as the fuel, by the combustion synthesis process. The lanthanide-doped nanostructures were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoluminescence. X-ray diffraction revealed the presence of tetragonal and monoclinic crystalline ZrO2 phases. The latter was found to be a minority phase as identified by Raman and corroborated by the observed europium luminescence when compared to the intraionic emission in crystalline tetragonal fibres grown by the laser floating zone technique. Bright red europium luminescence is observed at room temperature when the combustion synthesized zirconia powders are excited with ultraviolet radiation. The spectroscopic properties of the europium ions in the powders are ascertained by comparing combined excitation–emission measurements with those from crystalline fibres.