Fig. 4From: Enhance the Er3+ Upconversion Luminescence by Constructing NaGdF4:Er3+@NaGdF4:Er3+ Active-Core/Active-Shell NanocrystalsEnhancement factors of total emission intensities of NaGdF4:12%Er3+ core NPs, NaGdF4:12%Er3+@NaGdF4 active-core/inert-shell NPs, and the NaGdF4:12%Er3+@NaGdF4:x%Er3+(x = 6, 8, 10, and 12) active-core/active-shell NPs under 1540-nm excitationBack to article page