Intense Ultraviolet and Blue Upconverison Emissions in Tb~(3+)/Yb~(3+) Codoped KY_3F_(10) Nanocrystals

摘要

Tb~(3+)/Yb~(3+) codoped KY_3F_(10) nanocrystals with the average size of 45 nm were synthesized using a facile hydrothermal method. Under the excitation by a 976 nm laser, the codoped samples exhibited intense ultraviolet (~5D_3 → ~7F_6) and blue upconversion emissions (~5D_3 → ~7F_5) from Tb~(3+) ions. It was observed for the first time that the intense ultraviolet emission was two times stronger than the green emission of Tb~(3+), which was about 100 times stronger than the results previously reported. The upconversion mechanism was investigated based on the energy transfer from Yb~(3+) to Tb~(3+) and the cross-relaxation process between Tb~(3+) pairs.