High-temperature multimode self-calibrating thermometry enabled by lattice negative thermal expansion and luminescent Er3+/Tm3+ co-doping

The development of multi-mode self-calibrated photothermal thermometers for high-temperature applications is critically needed. However, most existing strategies are limited by single mode and severe thermal quenching. To address this, activator Er 3+ , Tm 3+ , and sensitizer Yb 3+ co-doped Y 2 W 3 O 12 (YWO) negative thermal expansion (NTE) phosphors have been developed, which exhibit effective resistance to thermal quenching in the up-conversion luminescence under 980 nm excitation. Moreover, an abnormal 3-photon-dominated up-conversion process was observed in YWO:18Yb/2Er/0.5Tm powder, attributed to the cross-relaxation (CR) between Er 3+ and energy transfer (ET) from Er 3+ to Tm 3+ . In addition, benefiting from the effect of NTE and the limited ET process in YWO:18Yb/2Er/0.5Tm, the relative intensity of the temperature-dependent up-conversion from the 2 H 11/2 , 4 S 3/2 , and 1 G 4 level, as well as their state splitting luminescence, exhibit distinct disparities. Furthermore, based on the luminescence intensity ratio (LIR) technique, a four mode self-calibrated optical thermometer using YWO:18Yb/2Er/0.5Tm powder is designed. The thermometer exhibits acceptable sensitivity, with absolute sensitivity ( S a) and relative sensitivity ( S r) reaching 0.006 K -1 at 293 K and 0.26% K -1 at 543 K, respectively. The developed thermometer could provide a reference for self-calibration, and its wide spectral operating range ensures the reliability of temperature sensing, which has the potential to be used in some high-temperature conditions.