Phase evolution and upconversion luminescence enhancement investigation from YF_3 to (α+β)-NaYF_4 by doping of Cu~(2+) ion

摘要

A facile, but effective, method has been developed for enhancing the upconversion (UC) luminescence efficiency of YF3: Yb3+, Er3+ microcrystals through doping of Cu2+ ion, accompanied by phase transformation from YF3 to alpha-NaYF4 to (alpha+beta)-NaYF4. The Cu2+ ion occupies the Y3+ ion crystal lattice site leading to positive vacancy and lower energy barrier in the reaction of forming alpha-NaYF4. In addition, we have also systematically investigated the phase transformation from YF3 to (alpha+beta)-NaYF4. With the extension of the reaction time, surface energy of the [1010] crystal plane decreases dramatically while that of the [0001] crystal plane increases accordingly, which may be the main reason for forming (alpha+beta b)-NaYF4. This synthesis strategy enables UC luminescence enhancement and simultaneous crystal phase transformation, which should inspire more even wider application of other UC host materials. (C) 2018 Elsevier B.V. All rights reserved.