Solvothermal synthesis and down/up conversion luminescence properties of Ln3+-doped NaYF4 nanocrystals

Ln(3+)-doped NaYF4 nanocrystals were synthesized by a facile citric acid-assisted solvothermal process. The effect of citric acid on the morphology and crystalline structure of the products was investigated, and the luminescence and fluorescence properties of the products were examined. Results show that citric acid plays a key part in controlling product morphology. As-synthesized cubic phase NaYF4 nanocrystals with narrow size (around 50 nm) could be an excellent host material for different doped lanthanide ions. Yb3+/Er3+ co-doped NaYF4 nanocrystals show strong up-conversion luminescence under 980 nm of continuous wave diode laser excitation, showing potential application as phosphors. (C) 2012 Elsevier B.V. All rights reserved.