Abstract
Doping heteroatom in phosphor can effectively improve luminescent properties, which has attracted great attention recently. GdAlO3 phosphors (GAP) doped with Er3+/Yb3+/Tm3+ were prepared via the co-precipitation method. Upon 980 nm excitation, strong blue, green, and red up-conversion (UC) emissions centered at 476, 524, 546, and 659 nm were observed, which could be successfully combined to form pure white light. It was found that changing the doping concentration of Er3+ and Yb3+ ions, the calcination temperature of the precursor, the laser power of the excitation light source, and doping Li+ could systematically adjust red/green/blue colors of GdAlO3:Er3+/Yb3+/Tm3+ phosphors to optimize the white emitting luminescence. When the Er3+ doping concentration of the phosphors increased, each color distribution successfully moved, making the maximum shift of the CIE coordinate. Finally, the influence of each factor on adjusting the UC white light performance and its mechanism were explored.
Highlights
The development of green and sustainable approaches have become a important theme
While, red and green emissions belong to the two-photon process of Er3+, so it was more favorable to obtain the energy transfer from Yb3+ to Tm3+, which made the relative intensity of red to blue and green to blue emissions decrease
The energy transfer between Er3+ and Yb3+ in the phosphors increased, the ratios of red to blue emission and green to blue emission intensity were improved with the increase of Er3+ doping concentration, so as to change each color distribution successfully, and making the maximum shift of the CIE coordinate of phosphors
Summary
The development of green and sustainable approaches have become a important theme. Lots of oxides with good chemical stability, mild synthesis conditions, that are eco-friendly, and have low phonon energy are being used as the host material to obtain UC white light which has attracted researchers’ attention (Rai et al, 2013; Chen et al, 2017; Annadurai et al, 2018). Yb3+ was used to sensitize Er3+, Tm3+ in GdAlO3 to obtain the UC white light, and the doping concentration of Er3+ and Yb3+ ions, the calcination temperature of the precursor, the laser power of the excitation light source, and Li+ doping were changed to adjust the intensity and relative proportion of red, green, and blue emissions. The UCPL spectra of the phosphors were recorded using an Ocean Optics PlasCalc-2000-UV-VIS-NIR plasma monitor control system and the exciting source was a MDL-H-980 980 nm infrared laser
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