Fabrication of oriented oxide films from exfoliated yttrium hydroxide layers: Enhanced photoluminescence and unexplored behavior of energy transfer

Layered yttrium hydroxide (LYH) nanospalates doped with different activators (Tb3+ and/or Eu3+) were hydrothermally synthesized and then successfully delaminated into ultrathin nanosheets of down to 1-3 nm thickness via intercalation reactions and mechanical agitation. Using the LYH nanosheets, highly [001] oriented yttrium hydroxide films were constructed through spin-coating. Based on the quasi-topotactic transformation from yttrium hydroxide to cubic Y2O3, [111] oriented oxide films were achieved by proper annealing. For the highly oriented Y2O3:0.05Eu film, the enhanced photoluminescence was obtained compared with the powder form due to the higher exposure of (222) facets. Through adjusting the incorporated activation ions, films with different color were obtained, and energy transfer from Tb3+ to Eu3+ was observed for the alternatively multilayer film, although Eu3+ and Tb3+ were located in different layers.