Doping-mediated thermal control of phase transition for supersensitive ratiometric luminescence thermometry

Intelligent luminescent materials, characterized by optical switching in response to thermal stimulation, are highly attractive for cutting-edge temperature sensing technologies. However, the exploration of sensitive and reliable thermometric materials remains challenging. Herein, we establish a phase-transition-driven thermometric model that relies on the reversible transition between the monoclinic (β) and tetragonal (α) phase of LiYO2:Dy3+ crystals under controlled thermal stimulations. Accordingly, the ratiometric emissions from hypersensitive electric diploe transitions (4F9/2 → 6H13/2) drastically varied across the phase-transition temperature range, rendering remarkable thermal sensitivity and resolution (Sr-max = 35.24 % K−1, δTmin = 0.009 K). We further demonstrate the extended control of phase-transition temperature and thermal hysteresis by a partial substitution approach. These findings highlight an endogenic approach to constructing customized luminescence thermometers via local crystal-field engineering, which raises new possibilities for practical sensing applications.