Up-conversion luminescence dependence on structure in zirconia nanocrystals

The zirconia samples containing two different concentrations of Er and Yb dopants were prepared using the Sol-Gel method and up-conversion luminescence was studied using the time-resolved techniques. The up-conversion luminescence depends on the oxygen content in surrounding gasses during annealing as well as on the annealing temperature. These dependencies indicate that ZrO₂ intrinsic defects annealing and generation, phase transition as well as dopant redistribution take place. The possible role of these processes on up-conversion luminescence is discussed. The results of experiments confirmed that the annealing temperature has a crucial influence on up-conversion luminescence for samples containing small concentrations of Er and Yb; whereas for samples containing large concentrations of Er and Yb, the primary change of up-conversion luminescence is due to the grain size growth during annealing. The optimal annealing temperature depends upon the Er and Yb ion concentration. It is crucial to obtain up-conversion zirconia material with high quantum efficiency.