Comprehensive study on different crystal field environments in highly efficient NaLaF4:Er3+ upconversion phosphor

Simultaneous size and luminescence control of NaYF4:Yb3+/RE3+ (RE=Tm, Ho) microcrystals via Li+ doping

“…Over the past decade, rare-earth (RE) doped upconversion (UC) materials have drawn much attention due to a multitude of possible applications in solar cells [1], solid-state lasers [2,3], optical imaging probes [4], photodynamic therapy [5], and plasma display panel [6]. UC luminescence refers to nonlinear optical processes, where near-infrared light with low energy, is converted to visible or ultraviolet light with higher energy.…”

“…The mechanism of the enhancement via Li + doping is discussed in details. 3 ) stock solutions were prepared by dissolving the corresponding rare earth oxide (99.99%) in nitric acid at elevated temperature. NaYF 4 :Yb 3+ /RE 3+ (RE = Tm, Ho) MCs via Li + doping were synthesized by a simple hydrothermal process with the assistance of citric acid.…”

“…As for the synthesis of NaYF 4 :Yb 3+ /Tm 3+ , 2.5 mmol citric acid (2 M, 1.25 mL), 5.5 mmol NaOH (4 M, 1.375 mL) and 10 mL deionized water were mixed and stirred for 10 min. Then 1 mmol RE(NO 3 ) 3 (0.79 mmol Y(NO 3 ) 3 (1 M, 0.79 mL), 0.2 mmol Yb(NO 3 ) 3 (0.5 M, 0.4 mL) and 0.01 mmol Tm(NO 3 ) 3 (0.1 M, 0.1 mL)) were added to above mixture and then thoroughly stirred for 30 min to form the RE-Cit 3À complex (2.5: 1 M ratio for Cit 3À : RE 3+ ). Meanwhile, 10 À x mmol NaF (1 M, 10 À x mL), x mmol LiNO 3 (1 M, x mL), x/2 mmol NH 4 HF 2 (2 M, x/4 mL) and 5 mL deionized water were mixed together and vigorously stirred to form a transparent homogeneous solution.…”

Temperature and impurity concentration effects on upconversion luminescence in LaInO3 doped with Er3+

“…Excitation in the IR region leads to a strong green luminescence at the doping concentrations below 2 mol % while an orange luminescence occurs at the concentrations above 2 mol %. S 3/2 populates the emitting levels of the green luminescence and the luminescence occurs [22,23]. As observed in the luminescence spectra, the ratio of red-togreen luminescence increases with the rise of impurity concentration.…”

Oxygen influence on luminescence properties of rare-earth doped NaLaF 4

“…We did not compare quantum yields for the samples; however, special experiment conditions were provided in order to compare intensities of luminescence for the samples having different oxygen content. [11,27]. It is clearly seen that the intensities of Er 3+ lines observed in Fig.…”