White and yellow light emission from ZrO2:Dy3+ nanocrystals synthesized by a facile chemical technique

Abstract

White and yellow light were obtained from ZrO2:Dy3+ nanocrystals which were synthesized by the solvent evaporation technique. The crystalline structure was studied by X-ray diffraction, resulting in a tetragonal and monoclinic mixture phases of ZrO2 when the powders were annealed at 600 °C and the zirconia monoclinic phase when they were thermal treated at 1000 °C. By means of atomic force microscopy images was observed that the synthesized powders are constituted by nanocrystals about 20 nm for the samples annealed at 600 °C, whereas samples annealed at 1000 °C were constituted by crystals about 135 nm, these features were confirmed by TEM images. Luminescence properties were analyzed by means of photo and cathodoluminescence; exhibiting emissions in the white light region of the chromatic diagram. In the case of photoluminescence white-warm color (x = 0.35, y = 0.37) was observed, which is close to pure white color; while for cathodoluminescence the emission was yellowish with coordinates (x = 0.39, y = 0.39) in the chromatic diagram. PL decay time measurements were carried out; a lifetime of 0.66 ms was found. In addition, the PL quantum efficiency was measured; the obtained value was as high as 45%.