Phosphors with rare earth (RE) ions are widely applied to optical temperature measurements. Moreover, the near-infrared (NIR) emission of phosphors has potential applications in the biological field. Herein, Gd₂O₃:x%Nd³⁺/Yb³⁺(0.2 ≤ x ≤ 0.8) samples are successfully synthesized by the sol–gel method, and their phase and morphology are characterized. The XRD data are refined by Rietveld. Under 980 nm continuous wave (CW) laser excitation, the upconversion (UC) and downshift (DS) emissions are studied. The temperature sensing performances of thermally coupled levels (TCLs) and non-thermally coupled levels (non-TCLs) of Gd₂O₃: Nd³⁺/Yb³⁺ phosphors are investigated through the fluorescence intensity ratio (FIR) technology. In the temperature range of 303–523 K, the maximum relative sensitivity of I_{761 nm}/I_{550 nm} reaches 6.54% K⁻¹, which is based on non-TCLs. At the same time, the maximum relative sensitivity of I_{761 nm}/I_{1000 nm–1500 nm} reaches 3.13%. In addition, the influence of the laser induced heating (LIH) effect is studied. Compared with square wave (SW) pumping, the relative sensitivity would decrease at CW excitation. Finally, the durability and temperature uncertainty are also discussed. The results prove that the Gd₂O₃:Nd³⁺/Yb³⁺ samples present higher relative sensitivity and durability and lower temperature uncertainty in the biological window. Therefore, the phosphors can be used as optical thermometers in the biological field.

中文翻译：

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用于高灵敏度光学测温的 Nd3+/Yb3+ 共掺杂 Gd2O3 荧光粉的可见光和近红外发光特性

具有稀土 (RE) 离子的磷光体广泛应用于光学温度测量。此外，荧光粉的近红外 (NIR) 发射在生物领域具有潜在应用。在此，通过溶胶-凝胶法成功合成了Gd ₂ O ₃ : x %Nd ³⁺ /Yb ³⁺ (0.2 ≤ x ≤ 0.8) 样品，并对其物相和形貌进行了表征。Rietveld 改进了 XRD 数据。在 980 nm 连续波 (CW) 激光激发下，研究了上转换 (UC) 和下移 (DS) 发射。_{Gd 2} O ₃ : Nd的热耦合能级（TCLs）和非热耦合能级（non-TCLs）的温度传感性能通过荧光强度比 (FIR) 技术研究³⁺ /Yb ^{3+荧光粉。}在303-523 K的温度范围内， I _{761 nm} / I _{550 nm}的最大相对灵敏度达到6.54% K ^-1，这是基于非TCLs的。同时， I _{761 nm} / I _{1000 nm–1500 nm}的最大相对灵敏度达到3.13%。此外，还研究了激光诱导加热 (LIH) 效应的影响。与方波（SW）泵浦相比，CW激发时的相对灵敏度会降低。最后，还讨论了耐久性和温度不确定性。结果证明 Gd ₂O ₃ :Nd ³⁺ /Yb ³⁺样品在生物窗口中呈现出更高的相对灵敏度和耐久性以及更低的温度不确定性。因此，荧光粉可用作生物领域的光学温度计。