Effects of Tm³⁺ concentration on upconversion luminescence and temperature-sensing behavior in Tm³⁺/Yb³⁺:Y₂O₃...

The effects of Tm³⁺ concentration on upconversion emission and temperature-sensing behavior of Tm³⁺/Yb³⁺:Y₂O₃ nanocrystals were investigated. Blue and red emissions were observed under 980 nm excitation. Both upconversion emissions and the blue to red intensity ratio were found to decrease with increasing Tm³⁺ concentration. The temperature-sensing performances of the samples were studied, the fluorescence intensity ratio of ¹G_4(a)→³H₆ (477 nm) and ¹G_4(b)→³H₆ (490 nm) transitions from Tm³⁺ ions was chosen as the thermometric index. The results showed that the sensor sensitivity was sensitive to Tm³⁺ ion concentration. The maximum sensitivity of ~32 × 10^-4 K^-1 was obtained for 0.1%Tm³⁺/5%Yb³⁺:Y₂O₃ nanocrystals at 344 K. Moreover, a marked optical induced heating effect was also found in the nanocrystals. The prepared Tm³⁺/Yb³⁺:Y₂O₃ nanocrystals could be used in temperature-sensing probes and in optical heaters.