Governing of down-shifting processes in LiLaP4O12:Tb3+,Yb3+ for enhancement of its near-infrared emission

Downshifting behavior of the Tb3+-Yb3+ co-doped nanocrystalline LiLaP4O12 powders synthesized by co-precipitation method was presented and discussed. The structural phase purity of obtained material was confirmed by X-ray diffraction (XRD) measurements. Strong enhancement of ytterbium 2F5/2→2F7/2 emission intensity was observed with decreasing Tb3+ concentration under UV excitation. Dependence of efficiency of energy transfer between dopants on pumping wavelength was investigated due to better understanding of down-shifting mechanism. It was found that luminescence intensity of Yb3+ decreased above 10 mol.% dopant content, what was caused by concentration quenching. The power dependence measurements were carried out at 77 and 300 K. The resulting slopes had the same value of 1, what indicated the existence of linear down-shifting process, independent of the temperature.

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