Impact of nitridation on the up-conversion luminescence property of Yb₃Al₅O₁₂: Er³⁺ phosphors upon 980 nm excitation

In this work, the nitriding method was used to improve the up-conversion (UC) luminescence intensity and temperature sensing sensitivity of phosphor materials. Yb3Al5O12: Er3+ and partially nitrided Yb3Al5O12-1.50xNx: Er3+ phosphors by using AlN as nitrogen source were prepared via solid-state reaction method. The influence of nitridation on the UC luminescence and temperature sensing properties of Yb3Al5O12: Er3+ phosphors upon 980 nm excitation were discussed. Almost pure red UC emission was obtained, and the intensity of the red UC emission of the samples was enhanced by 25 % after nitridation. Meanwhile, the absolute temperature sensitivity respectively derived from the intensity ratios of the green and red emissions increased by 5 % and 50 % after nitridation. Judd-Ofelt theory was utilized to analyze the change of the crystal field environment around Er3+ and confirmed that the introduction of N3- reduced the symmetry around Er3+ and strengthened the covalence between Er3+ and ligands, which may result in the enhancement of UC emission intensity and temperature sensing sensitivity. The experiment proved that Yb3Al5O12: Er3+ red UC phosphors had potential application in luminescence imaging and temperature sensors.