Yb/Er/Tm tri-doped Na3ZrF7 upconversion nanocrystals for high performance temperature sensing

Non-contact optical thermometry based on fluorescence intensity ratio (FIR) technique has been widely researched over the past few decades. However, the reported systems exhibit two important shortcomings including the existence of a few interferential signals in addition to the required spectral bands for FIR and the absence of internal standard for reference signal. Herein, only two emission bands of Er 3+ : 4 F 9/2 → 4 I 15/2 (~673 nm) and Tm 3+ : 3 H 4 → 3 H 6 (~800 nm) are achieved in Yb/Er/Tm tri-doped Na 3 ZrF 7 nano-system. Moreover, the upconversion (UC) emission intensity of Er 3+ keeps unchanged with the rising of temperature, which is applied as reference signal; while that of Tm 3+ enhances evidently, which is applied as temperature signal. The calculated maximum absolute temperature sensitivity (S a ) and relative temperature sensitivity (S r ) are 0.17 K −1 at 393 K and 1.76% K −1 at 313 K, respectively.