Enhanced optical temperature sensing performance based on dual emission centers of Y2O3: Yb3+, Tm3+, Ho3+ upconversion phosphor

Y2O3: 5%Yb3+, 0.5%Tm3+, z%Ho3+ (z=0, 0.1, 0.5, 1.0) upconversion luminescent materials were synthesized by CO2 laser zone melting method. The upconversion luminescence (UCL) spectra of the samples were recorded with the excitation of 980 nm laser, and the energy transfer processes among doped rare earth (RE) ions were analyzed. The introduction of Ho3+ ions into Y2O3: 5%Yb3+, 0.5%Tm3+ gave the samples four distinct UCL bands, including blue, green, red, and infrared emission bands. The temperature sensing characteristics based on the fluorescence intensity ratio (FIR) of non-thermally coupled levels (NTCLs) of Tm3+ and Ho3+ ions were studied, and the derived maximum relative sensitivity (SR) reached impressive value of 0.0138 K-1 (298 K). Compared to the materials doped with single emission center of either Tm3+ or Ho3+ ions, the luminescent material co-doped with both Tm3+ and Ho3+ ions exhibited higher sensitivity while maintaining a wide temperature measurement range. The research results indicate that Y2O3: Yb3+, Tm3+, Ho3+ upconversion phosphor promises broad application prospects in optical temperature measurement.