Shiying Tan,Xusheng Wang,Yan Zhao,Yanxia Li,Xi Yao
Rare earth doped upconversion luminescent materials have the advantages of low toxicity, high chemical stability, excellent photostability, narrow emission band, and long luminescent life, but their low fluorescence quantum efficiency restricts their practical application in the field of temperature sensing. In this paper, Er 3+ doped KYb(MoO 4 ) 2 (KYM) phosphors were synthesized by a temperature solid state reaction method. When the doped concentration is 5 mol%, the luminescence intensity get its strongest value. On this basis, 2 mol% trivalent ions Gd 3+ , La 3+ and Y 3+ (R 3+ ) were doped respectively, and the luminescence intensity increased by about 2 times. By the fluorescence intensity ratio technique, the KYM:5Er phosphor has the maximum absolute temperature sensitivity of 0.0106 K -1 . By codoping 2 mol% Gd 3+ in KYM:5Er, the upper limit of temperature measurement increased from 513 K to 663 K, which shows that Er 3+ -doped and Er 3+ /R 3+ -codoped KYM have the potential as temperature sensors .
The KYb(MoO 4 ) 2 : Er 3+ , Y 3+ phosphors were synthesized by high temperature solid state reaction method. By further doping Y 3+ ions, the near-infrared (NIR, 804 nm, 4 I 9/2 → 4 I 15/2 ) luminescence of KYb(MoO 4 ) 2 : 0.1 % Er 3+ phosphor is greatly enhanced. Based on the upconversion luminescence (UCL) spectra, the optimal doping concentration of Y 3+ ions were 7.5 %. Its near-infrared UCL intensity is about 26.9 times that of undoped Y 3+ ions. Through a series of characterization methods, we find that the enhancement of NIR upconversion emission is due to the generation of defect bands. It plays a crucial role in facilitating the transfer of energy from green light level ( 2 H 11/2 , 4 S 3/2 ) to red light level ( 4 F 9/2 ) and near-infrared level. To explain the luminescence mechanism, the power dependence, UV-VI-NIR absorption spectra , excitation spectra at 804 nm and emission spectra at 380 nm were studied. In addition, the 804 nm single near-infrared UCL intensity of KYb (MoO 4 ) 2 : Er 3+ , Y 3+ shows a linear variation with temperature in the temperature range of 298 K–673 K. The maximum sensitivity is 0.13 % K −1 . This study provides a new method and theoretical support for the application of near-infrared UCL in optical temperature measurement.
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