Breaking Sensitivity Barriers in Luminescence Thermometry: Synergy Between Structural Phase Transition and Luminescence Thermal Quenching

TL;DR

This paper introduces a novel luminescence thermometry approach that combines structural phase transition and luminescence quenching to achieve higher sensitivity and broader temperature range, including first-time observation of Mn4+ luminescence in high-temperature LaGaO3.

Contribution

It demonstrates a synergistic method leveraging phase transition and ion luminescence to enhance thermometry sensitivity and range, with new observations of Mn4+ luminescence in LaGaO3 at high temperatures.

Findings

Maximum sensitivity of 4.5 K-1 at 400 K.

Extended temperature range with sensitivity >1% K-1.

First observation of Mn4+ luminescence in high-temperature LaGaO3.

Abstract

One of the key parameters determining the performance of a luminescent thermometer is its relative sensitivity. In ratiometric luminescence thermometry, high relative sensitivity to temperature variations is typically achieved when the two monitored emission bands exhibit opposite thermal monotonicity. However, realizing a thermal enhancement in the luminescence intensity of one of the emission bands remains a significant challenge. In this study, we present a novel approach that leverages the synergistic effect of two phenomena: (1) the high thermal sensitivity of Mn4+ ion luminescence, and (2) a thermally induced structural phase transition in LaGaO3, which facilitates the enhancement of the luminescence signal from Tb3+ ions in the high-temperature phase of the host material. This dual effect not only led to an increased maximum relative sensitivity but also extended the temperature range over which the sensitivity exceeded 1% K-1. The highest recorded sensitivity was 4.5 K-1 at 400 K. Additionally, to the best of our knowledge, the luminescence of Mn4+ ions in the high-temperature phase of LaGaO3:Mn4+ was observed and reported here for the first time. The thermally induced modifications in the emission profile of LaGaO3:Mn4+,Tb3+ enabled the development of a quadruple ratiometric luminescence thermometer, with complementary operating ranges, offering enhanced versatility and accuracy across a broad temperature span.