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

TL;DR

This study investigates how dopant concentration and morphology affect the dual-phase transition thermometric performance of Li3Sc2(PO4)3:Eu3+ luminescent materials, revealing tunable sensitivity and the first dual-range luminescent thermometer.

Contribution

It introduces a novel dual-phase transition luminescent thermometer with tunable temperature ranges based on dopant and morphological modifications.

Findings

Reversible phase transitions at 160 K and 550 K detected by spectroscopic changes.

Sensitivity of 7.8% K-1 at 160 K and 0.65% K-1 at 550 K achieved.

Dopant concentration and annealing influence phase transition temperatures and morphology.

Abstract

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, the present study offers a comprehensive analysis of the temperature-dependent spectroscopic properties of Li3Sc2(PO4)3:Eu3+. The findings reveal that the studied material undergoes two reversible phase transitions: {\gamma}LT - {\alpha}/\b{eta} phase transition at approximately 160 K, followed by an \b{eta} HT transition around 550 K. These transitions are evidenced by notable alterations in the emission spectra and luminescence decay kinetics of Eu3+ ions. By employing an appropriate luminescence intensity ratio, the sensitivity was determined to be 7.8 % K-1 at 160 K for 0.1%Eu3+ and 0.65 % K-1 at 550 K for 0.5%Eu3+. Furthermore, the study demonstrates that the phase transition temperature in Li3Sc2(PO4)3:Eu3+ 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.