Improving Optical Temperature Sensing Performance of Er³⁺ Doped Y₂O₃ Microtubes via Co-doping and Controlling...

This work presents a new method to effectively improve the optical temperature behavior of Er³⁺ doped Y₂O₃ microtubes by co-doping of Tm³⁺ or Ho³⁺ ion and controlling excitation power. The influence of Tm³⁺ or Ho³⁺ ion on optical temperature behavior of Y₂O₃:Er³⁺ microtubes is investigated by analyzing the temperature and excitation power dependent emission spectra, thermal quenching ratios, fluorescence intensity ratios, and sensitivity. It is found that the thermal quenching of Y₂O₃:Er³⁺ microtubes is inhibited by co-doping with Tm³⁺ or Ho³⁺ ion, moreover the maximum sensitivity value based on the thermal coupled ⁴S_3/2/²H_11/2 levels is enhanced greatly and shifts to the high temperature range, while the maximum sensitivity based on ⁴F_9/2(1)/⁴F_9/2(2) levels shifts to the low temperature range and greatly increases. The sensitivity values are dependent on the excitation power, and reach two maximum values of 0.0529/K at 24 K and 0.0057/K at 457 K for the Y₂O₃:1%Er³⁺, 0.5%Ho³⁺ at 121 mW/mm² excitation power, which makes optical temperature measurement in wide temperature range possible. The mechanism of changing the sensitivity upon different excitation densities is discussed.