Highly Intensified Upconversion Luminescence of Ca2+-doped Yb/Er:NaGdF4Nanocrystals Prepared by a Solvothermal Route

Abstract Upon introducing Ca 2+ dopants into the grain lattices by substituting Gd 3+ ions, irregular Yb/Er:NaGdF 4 nanocrystals prepared through a simple solvothermal route convert into highly uniform nanorods. Meanwhile, their upconversion luminescence intensifies by about 200 times, probably due to a modification of the crystal structure of NaGdF 4 and an improvement in the crystallinity of the nanophase.