Temperature sensor based on the UV upconversion luminescence of Gd3+ in Yb3+–Tm3+–Gd3+ codoped NaLuF4 microcrystals

Abstract

Optical temperature sensing characteristics based on the ultraviolet (UV) upconversion luminescence (UCL) of Gd 3+ ions are reported here for the first time. Under 980 nm excitation, the temperature dependence five-photon UV UCL from the 6 P J and 6 I J levels of Gd 3+ ions in NaLuF 4 :Yb 3+ , Tm 3+ , Gd 3+ microcrystals were investigated systematically. The fluorescence intensity ratios (FIR) of two pairs of thermally coupled levels ( 6 P 5/2 , 6 P 7/2 and 6 I 9/2 , 6 I 7/2 ) were studied as a function of temperature in a range of 298-523 K.The maximum sensor sensitivities were found to be about 0.0004 K À1 (333 K) and 0.0029 K À1 (298 K) by exploiting the UC emissions from the 6 P J and 6 I J levels, respectively. This suggests that the Gd 3+ -based UCL materials are promising prototypes for application as multi-mode probes for use in bio-separation, MRI imaging, optical thermometers, etc.

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“…[1][2][3][4][5][6]. The optical temperature sensing, based on the UC emission of RE ions, by means of the fluorescence intensity ratio (FIR) technique has received significant attention as a result of its high sensitivity and accuracy [7][8][9].…”

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Enhanced temperature sensing response of upconversion luminescence in ZnO–CaTiO3: Er3+/Yb3+ nano-composite phosphor

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