Thermal Quenching Resistant Luminescence and Multimodal Self-Calibrated Temperature Sensing Properties of Gd2(WO4)3:Er3+ Phosphors

Multimodal temperature sensing minimizes environmental interference through cross-validation by integrating both upconversion (UC) and downconversion (DC) modalities and exploiting differences in the thermal responses of emissive transitions in a single activator center. Er 3+ -doped Gd 2 (WO 4 ) 3 phosphors were synthesized via a high-temperature solid-state reaction. This material nables multimodal self-calibrating temperature sensing based on both DC and UC luminescence and exhibits excellent resistance to thermal quenching. Notably, under 360 nm excitation (DC mode), the 530 nm emission maintained 96% of its intensity from 313 to 493 K, and under 980 nm excitation (UC mode) it remained within ±5% from 313 to 573 K. Additionally, the 824 nm emission (under 980 nm excitation) exhibited a 3.37-fold enhancement from 313 to 573 K, attributed to thermally activated cross-relaxation (CR). We also explored a multimodal self-calibrating temperature sensing system using fluorescence intensity ratio (FIR) techniques, employing the I 530 /I 551 ratio in the DC mode and the I 824 /I 551 ratio in the UC mode. Notably, the I 824 /I 551 ratio achieved a maximum relative sensitivity (S r ) of 2.21% K -1 at 313 K. A dual-mode temperature fusion platform was developed by integrating DC and UC channels. In this scheme, the multimodal FIR strategy synergistically minimizes systematic errors through cross-validation while enhancing reliability by combining thermal-quenching resistance and thermally activated emission. This work establishes a novel dual-mode material system framework for high-accuracy optical thermometry.