Upconversion luminescence thermal enhancement and emission color modulation of LiYGeO4:Er3+/Yb3+ phosphors

A series of LiYGeO4:Er3+/Yb(3+ )phosphors were synthesized by solid-phase sintering method, and the up -conversion luminescence (UCL) thermal enhancement and emission color modulation were investigated under 980 and 1550 nm laser excitations. When Er3+ doping concentration is kept at 0.02, the UCL intensity reaches the maximum at the Yb3+ doping concentration with 0.20. With temperature increasing from 303 to 723 K, the green UCL intensities of samples reach maximum enhancement as high as 4.56 and 11.54 times under 980 and 1550 nm laser excitations, respectively. The optical temperature sensing performance of these samples was evaluated by luminescence intensity ratio (LIR) technology, and the maximum absolute sensitivities in LiYGeO4:0.02Er(3+)/0.40Yb(3+) are 0.01020 K-1 at 625 K and 0.01026 K(-1 )at 655 K under 980 and 1550 nm laser excitations, respectively. In addition, the modulation of UCL color can be realized by changing laser excitation power, temperature and excitation wavelength. These results show that LiYGeO4:Er3+/Yb3+ phosphors can be used as high-temperature optical thermometer and anti-counterfeiting. (C) 2022 Elsevier B.V. All rights reserved.