Ultra-Large Unilamellar Nanosheets Efficiently Exfoliated from (Y0.95Eu0.05)2(OH)5NO3•nH2O and Their Self-Assembly into Oriented Oxide Film with Enhanced Photoluminescence Properties

Two dimensional nanophosphors of high quality play an important role in the miniaturization and intelligentization of opto-electronic components. In this present work, ultra-large (>= 30 mu m) single crystals of (Y0.95Eu0.05)(2)(OH)(5)NO3 center dot nH(2)O layered rare earth hydroxide (LRH) with a hexagonal shape have been synthisized via autoclaving the rare-earth nitrate/NH4OH reaction system in the presence of ammonium nitrate (NH4NO3). The nitrate ions, existing in the interlayer gallery of layered rare earth hydroxide, exhibit facile exchanges with oleate anions by hydrothermal anion exchange. Furthermore, the interlayer distance can thus be expanded from similar to 0.9 nm for the pristine LRHs to similar to 3.60 nm for the intercalated ones, which are then efficiently delaminated into unilamellar nanosheets with a lateral size of >= 10 mu m and a thickness of similar to 1.50 nm. The obtained nanosheets are single crystaline. Highly [111] oriented, dense (Y0.95Eu0.05)(2)O-3 phosphor films with excellent optical transparency and a greatly enhanced luminescence intensity have been constructed via self-assembly of ultra-large unilamellar LRH nanosheets, followed by proper annealing.