Defect structure and up-conversion luminescence properties of ZrO2:Yb3+,Er3+ nanomaterials.

The up-converting ZrO2:Yb3+,Er3+ nanomaterials were prepared with the combustion and sol-gel methods. FT-IR spectroscopy was used for analyzing the impurities. The crystal structures were characterized with X-ray powder diffraction and the mean crystallite sizes were estimated with the Scherrer formula. Up-conversion luminescence measurements were made at room temperature with IR-laser excitation at 977 nm. The IR spectra revealed the conventional NO3- and OH- impurities for the combustion synthesis products. The structure of the ZrO2:Yb3+, Er3+ nanomaterials was cubic except for the minor monoclinic and tetragonal impurities obtained with the sol-gel method. The materials showed red (650-700 nm) and green (520-560 nm) up-conversion luminescence due to the 4F9/2-->4I15/2 and (2H11/2, 4S3/2)-->4I15/2 transitions of Er3+, respectively. The products obtained with the combustion synthesis exhibited the most intense luminescence intensity and showed considerable afterglow.