Optical temperature sensing based on thermal, non-thermal coupled levels and tunable luminescent emission colors of Er3+/Tm3+/Yb3+ tri-doped Y7O6F9 phosphor

The Er3+/Tm3+/Yb3+ tri-doped Y7O6F9 phosphor is synthesized by a typical hydrothermal method. The Y7O6F9: 0.6%Er3+/0.2%Tm3+/15%Yb3+ phosphor is selected for the study. The up-conversion characteristics and temperature sensing performances of the phosphor are investigated under the excitation of 980 nm laser. The temperature sensing performances are investigated in the temperature range of 306–546 K based on thermal and non-thermal coupled levels by using fluorescence intensity ratio technology. The maximum sensitivity is 54.3 × 10−3 K−1 at 546 K, which is based on 3F2,3 (red emission at 695 nm of Tm3+) and 4S3/2 (green emission at 545 nm of Er3+) levels. After comparison, it is found that the sensing sensitivity of Y7O6F9: 0.6%Er3+/0.2%Tm3+/15%Yb3+ phosphor is relatively high. The excellent temperature sensing performances of the phosphor are verified. What's more, the white luminescent emission of the phosphor is achieved by adjusting excitation power and sample temperature during the experiment. And the luminescent emission color of the phosphor can be modulated widely. The above experimental results not only enable us to have a deeper understanding of tunable upconversion luminescent emission and optical temperature sensing, but also provide a significant step for high sensitivity thermometry, white light illuminating and color displaying. •White luminescent emission is achieved by adjusting excitation power and sample temperature.•The luminescent emission color can be modulated widely.•The up-conversion photon absorption process at room temperature and high temperature is investigated.•Sensing sensitivity of the phosphor is relatively high.