Fig. 3From: Synthesis and Luminescence Properties of Water Soluble α-NaGdF4/β-NaYF4:Yb,Er Core–Shell NanoparticlesXRD patterns of NaYF4: Yb, Er crystals which were synthesized without α–NaGdF4 core existing with different reaction times. (a) 2 h, (b) 6 h, (c) 12 h, and (d) 24 hBack to article page