Rare earth ion doped upconversion (UC) luminescent materials could show potential applications in optical temperature sensing. To develop new UC phosphors doped with Yb³⁺/Ho³⁺ activators, a series of La_9.67Si₆O_26.5:Yb³⁺–Er³⁺/Ho³⁺ samples were prepared by a solid-state reaction method, and the temperature-sensing properties were evaluated on the basis of the UC spectra. The phase, structure and morphology of the samples were analyzed by XRD, Rietveld refinement and SEM techniques, respectively. The characteristic emission peaks of both Er³⁺ and Ho³⁺ appeared and the UC mechanism was discussed. Different strategies for optical temperature sensing were employed for Er³⁺ and Ho³⁺. The fluorescence intensity ratio (FIR) for the two green emissions of Er³⁺ originating from thermally-coupled levels followed the Boltzmann distribution. The effect of the pump power on the sensor sensitivities was investigated in detail. The relative standard deviation and temperature uncertainty were also evaluated. For the Ho³⁺-activated LSO, the red and green emissions derived from non-thermally-coupled levels were used for temperature sensing. The UC energy transfer processes were discussed in detail to explain the change in the FIR with temperature. High absolute sensitivity was obtained in this phosphor. The above investigations could be instructive in exploring other new luminescent materials for optical temperature sensing.

中文翻译：

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基于泵浦功率相关的上转换发光的温度感测发光材料La9.67Si6O26.5：Yb3 + –Er3 + / Ho3 +

掺杂稀土离子的上转换（UC）发光材料可能在光学温度感测中显示出潜在的应用。为了开发掺有Yb ³⁺ / Ho ³⁺活化剂的新型UC荧光粉，通过固相反应法制备了一系列La _9.67 Si ₆ O _26.5：Yb ³⁺ -Er ³⁺ / Ho ³⁺样品，基于UC光谱评估温度感测特性。分别通过XRD，Rietveld精制和SEM技术分析了样品的相，结构和形态。Er ³⁺和Ho ³⁺的特征发射峰出现并讨论了UC机制。对于Er ³⁺和Ho ³⁺，采用了不同的光学温度传感策略。来自热耦合能级的Er ³⁺的两种绿色发射的荧光强度比（FIR）遵循Boltzmann分布。详细研究了泵浦功率对传感器灵敏度的影响。还评估了相对标准偏差和温度不确定度。对于何³⁺在激活的LSO中，非热耦合水平产生的红色和绿色发射被用于温度感测。详细讨论了UC能量传递过程，以解释FIR随温度的变化。在该荧光体中获得了很高的绝对灵敏度。上述研究可能对探索用于光学温度感测的其他新型发光材料具有指导意义。