Luminescent Platform for Thermal Sensing and Imaging Based on Structural Phase-Transition

TL;DR

This study explores a new luminescent material X that undergoes a structural phase transition, enabling highly sensitive and tunable thermal sensing and imaging using Eu3+ ions, including the first demonstration of Eu3+-based thermal imaging.

Contribution

It introduces a novel host material X with phase-transition properties for Eu3+-based luminescent thermometry and thermal imaging, including filter-free digital camera implementation.

Findings

X exhibits a phase transition affecting Eu emission spectra and kinetics

Achieved maximal sensitivities of 3.4 (ratiometric) and 1.0 (lifetime)

First demonstration of Eu3+-doped phosphor for thermal imaging

Abstract

The remarkable sensitivity of the luminescent properties of Eu3+ ions to structural changes in host materials has been well-explored for years. However, the application of this feature of Eu3+ in materials exhibiting thermally induced structural phase transitions for the development of luminescent thermometers has only recently been proposed. The narrow operating range of such thermometers necessitates the exploration of new host materials. In response to this demand, this study carefully analyzes the spectroscopic properties of X as a function of temperature and dopant ion concentration. As demonstrated, X undergoes a phase transition from a low-temperature monoclinic phase to a high-temperature trigonal structure, resulting in significant changes in both the emission spectrum shape of Eu ions and the depopulation kinetics of the 5D0 level. Consequently, X can be utilized as both a ratiometric and a lifetime-based luminescence thermometer, achieving maximal relative sensitivities of 3.4 and 1.0 or the respective approaches. Additionally, this work highlights how increasing the concentration of Eu3+ ions enables the tuning of the thermal operating range to achieve optimal thermometric performance. Moreover, an implementation of ratiometric approach of temperature sensing and imaging with X using digital camera without filters was demonstrated. This is the first report that demonstrates thermal imaging using Eu3+-solely doped phosphor. This finding underscores the potential of X as a versatile host material for advanced luminescent thermometry applications.