Shape controllable synthesis and enhanced upconversion photoluminescence of β-NaGdF4:Yb3+, Er3+ nanocrystals by introducing Mg2+

Shape controllable synthesis and enhanced upconversion photoluminescence of β-NaGdF₄:Yb³⁺, Er³⁺ nanocrystals by introducing Mg²⁺

Yang Yong-Xin^{1, 2}, Xu Zheng^{1, 2, †}, Zhao Su-Ling^{1, 2}, Liang Zhi-Qin^{1, 2}, Zhu Wei^{1, 2}, Zhang Jun-Jie^{1, 2}

(color online) (a) and (b): Power dependence of UC emissions of NaGdF₄:20-mol% Yb³⁺, 2-mol% Er³⁺ of (a) 0-mol% and (b) 6-mol% Mg²⁺ dispersions in cyclohexane with a 980-nm semiconductor laser. (c): Energy level diagrams of Er³⁺ and Yb³⁺ ions, showing possible energy transfer mechanisms for red and green UC emissions of Er³⁺ activators in the hosts.