Modulating Thermometric Performance via Dopant Concentration and Morphology in a Luminescence Thermometer Exhibiting Dual Structural Phase Transitions

High Resolution Image Download MS PowerPoint Slide Expanding the operational range of luminescent thermometers that utilize thermally induced structural phase transitions in lanthanide-doped materials necessitates the exploration of novel host matrices with diverse thermal behaviors. In line with this objective, this study offers a comprehensive analysis of the temperature-dependent spectroscopic properties of Li 3 Sc 2 (PO 4 ) 3:Eu 3+ . The findings reveal that the studied material undergoes two reversible phase transitions: the γ LT → α/β phase transition at approximately 160 K, followed by a β → γ HT transition around 550 K. These transitions are evidenced by notable alterations in the emission spectra and luminescence decay kinetics of Eu 3+ ions. By employing an appropriate luminescence intensity ratio, the sensitivity was determined to be 7.8% K –1 at 160 K for 0.1% Eu 3+ and 0.65% K –1 at 550 K for 0.5% Eu 3+ . Furthermore, the study demonstrates that the phase transition temperature in Li 3 Sc 2 (PO 4 ) 3:Eu 3+ can be modulated through variations in dopant ion concentration and annealing conditions, which in turn influence the material’s morphology. These strategies enable the fine-tuning of thermometric performance in phase transition-based luminescent thermometers. To the best of our knowledge, this represents the first report in the literature of a luminescent thermometer exhibiting dual thermal operating ranges.