Morphology control and upconversion luminescence enhancement of Na1-xLixY.78-yLuyF4:Er.02Yb.2 microcrystals by doping ions with different valences

Trivalent lanthanide ion (Ln 3+ ) doped UC materials can emit visible light under near-infrared (NIR) excitation due to anti-stokes shift and have received wide attention. In this paper, we presented a new strategy to synthesize the uniform and smooth microstructures (rodlike and tubular) based on hexagonal phase NaYF 4 microcrystals . Moreover, we systematically discussed the method of enhancing the upconversion (UC) luminescence intensity via co-doping the ions with different valences (Li + and Lu 3+ ) in order to tailor the environment around lanthanide ions. The UC intensities in the two microstructures were significantly improved. The results suggested the great application potential of tubes and rods of β-NaYF 4 microcrystals in anti-counterfeiting, laser media, photonic crystals , and waveguides .