Description:
Y 2 O 3 : 0.5 mol%Tm 3+ /x mol%Yb 3+ (x = 3, 5, 7, 10) fluorescent materials have been synthesized by the CO 2 laser zone melting method. With 980 nm excitation, the up-conversion luminescence (UCL) emission bands corresponding to 1 G 4 → 3 H 6 , 1 G 4 → 3 F 4 , 3 F 2,3 → 3 H 6 , and 3 H 4 → 3 H 6 transitions of Tm 3+ ions were obtained in visible and near-infrared spectral regions, among which the fluorescence produced by 1 G 4 → 3 H 6 , 3 H 4 → 3 H 6 transitions shows obvious Stark splitting. Besides, the optimal doping concentration of Yb 3+ is 5 mol%. The up-conversion luminescence spectra of Y 2 O 3 :0.5 mol%Tm 3+ /5 mol%Yb 3+ were recorded over the temperature range from 224 K to 873 K. The temperature sensing properties of 3 F 2,3 and 3 H 4 , 1 G 4(a) and 1 G 4(b) energy levels of Tm 3+ ions were investigated by the fluorescence intensity ratio (FIR) method in a wide temperature range, and the possibility of using 3 H 4(a) and 3 H 4(b) thermally coupled levels (TCLs) of Tm 3+ ions for temperature sensing was developed. The results show that 1 G 4(a) and 1 G 4(b) , 3 F 2,3 and 3 H 4 , 3 H 4(a) and 3 H 4(b) of Tm 3+ ions are TCLs, and the Stark sub-levels own relatively high absolute sensitivity at low temperature, whereas the 3 F 2,3 and 3 H 4 TCLs of Tm 3+ ions are more suitable for high temperature measurement. The results show that the Tm 3+ /Yb 3+ :Y 2 O 3 fluorescent material can be a promising candidate of optical thermometry