ABSTRACT
Owing to some special superior features, luminescence ratiometric thermometry has acquired popularity, particularly dual excitation single emission (SBR) and single excitation dual emission (FIR). Nonetheless, it remains difficult to create ratiometric thermometry that can operate in multiple modes. The integration of FIR and SBR techniques paves the way for advancements in various fields, including industrial processes, environmental monitoring, and biomedical applications, where accurate temperature measurements are crucial for optimal performance and safety. In this work, we describe a way to measure temperature based on the light-induced fluorescence of Pr3+ in NaSrGd(MoO4)3 (NSGM). The optical properties were investigated by UV-visible absorption, PL, and PLE spectroscopy. On the one hand, the emission of Pr3+ exhibits varying temperature-dependent behavior upon 450 nm excitation. Thus, a thermometer based on the FIR between the Pr3+ levels has been generated, with the highest sensitivity of approximately 0.83% K-1 over a wide temperature range of 290-440 K. Furthermore, the SBR luminescent thermometer was evaluated in the same temperature range. The effect of the Pr3+ concentration on red-emitting SBR luminescent thermometers was investigated in detail. The Sa and Sr values gradually increase, with the Pr3+ content reaching a maximum Sr value of 2.4% K-1 at 413 K for the NSGM:10% Pr3+ phosphor. These results show that Pr3+ ions have the potential to be optically active centers for luminescent thermometer applications using FIR and SBR techniques. It is anticipated that the present work will inspire other researchers to employ multi-mode optical ratiometric thermometry more widely.
ABSTRACT
A lot of people are interested in optical thermometry, especially the new single-band ratiometric (SBR) technology for measuring temperature. But since SBR thermometry is still in its infancy, it is highly constrained when compared to the conventional dual-band ratiometric approach. In this paper, we propose a new SBR thermometry technique that is based on both the ground and excited state absorption processes. When these two different processes occur, the green emission of Tb3+ in the low-cost host of NaSrGd(MoO4)3 (NSGM) responds to changes in temperature in a way that is the exact opposite of what you would expect. The maximum luminescence intensity was obtained for an optimum terbium concentration of 40% mol. The resulting chromaticity coordinates (x, y) and high correlated color temperature (CCT) values of the doped phosphors give a thermally stable cold emission in the green region with a color purity of about 92%. Using this intriguing characteristic as a foundation, sensitive SBR thermometry has been successfully developed, and the optical properties of the material have also been thoroughly researched. At room temperature, the relative sensitivity reaches its maximum value of 10.9% K-1. These findings may give important information that may be used in the design of new luminescent thermometers that have excellent performance.
