“…This means that the upconversion luminescence colors can be finely tuned by adjusting the doping concentration of Yb 3+ . Similar phenomena about the variation tendencies of green and red upconversion luminescence intensities and red/green intensity ratios versus the Yb 3+ concentrations were observed in previous reports . Figure presents the luminescence dynamic curves for NaGd(MoO 4 ) 2 : Yb 3+ /Er 3+ tetragonal microplate crystals with different Yb 3+ concentrations at 553 nm ( 4 S 3/2 → 4 I 15/2 ) and 657 nm ( 4 F 9/2 → 4 I 15/2 ) under the excitation of 980 nm.…”