We report on multiphoton white-light upconversion in vacuum for Pechini synthesis Yb3Al5O12(YbAG) and combustion synthesis (Yb; Y2)O3nanopowders under IR excitation. Their intense white-light upconversion is attributed to charge transfer luminescence superimposed upon a broadband emission. Unlike common nanoscale phosphors, which show low luminescence efficiency, the intensity of white-light upconversion for nanopowders is similar to that of their bulk counterparts. The luminary efficacy of the upconversion is estimated to be 10-15 lm W-1, and the Commission Internationale d'Eclairage (CIE) coordinates can be widely tuned by the excitation power, pressure, and codoping ratio. The nano-YbAG sample exhibits a longer buildup time for emission, a higher excitation threshold, and a wider CIE range than the oxide nanopowders.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics