Luminescence Thermometry - Crossing the Limits of Operating Range

Abstract

Temperature is one of the fundamental thermodynamic parameters that affects and regulates the rate and nature of the chemical, physical and biological processes. A precise and accurate measurement of temperature is essential across a broad spectrum of areas, such as nanomedicine, electronics, aerospace, climate, food storage, etc. Therefore, there is a great variety of temperature sensors (which currently account for ≈80% of the worldwide sensor market), and their operating modes can be divided into two main groups: contact and noncontact techniques. However, in some specific cases, only non-contact systems may provide accurate information about temperature and its distribution over an area. These are as follows: harsh environments (for example inside turbines), fast-moving objects (gas jets), intense magnetic fields that prevent the use of metals or materials with free electric charges (NMR therapies) or when the size of the system to measure is smaller than 10 μm (cellular tracking or microelectronic circuits). One promising solution that can break through those limitations is luminescence thermometry (LT). LT is a non-contact and non-invasive spectroscopic technique based on the changes in a phosphor emission when temperature changes (e.g., the intensity of a band, relative intensities, band shapes, excited-state lifetimes, etc.).We shall present our original approach to use intra- and inter- configurational transitions of Pr3+ ion for accurate temperature reading with high relative sensitivity over an outstandingly wide range of temperatures. Studies were focused on Y2SiO5:0.05%Pr and its chemically modified version by a bandgap engineering approach (replacing Si with Ge). The addition of Ge to replace Si was expected to decrease the host bandgap – energetic separation of its valence and conduction bands. Consequently, we expected that the 5d→4f luminescence would be more susceptible to temperature quenching. This, in turn, allowed to control the range of temperatures within which the 5d→4f/4f→4f emission intensity ratio could be utilized for thermometry. Furthermore, possibilities to further improve such sensors will be discussed by widening the operating range of distinct thermometers.This presentation will show that luminescence thermometers working in unprecedented board operating range can be effectively constructed and managed. Further analysis of such an approach will be carefully discussed. This research was supported by the National Science Centre, Poland under grant #2020/37/N/ST5/02507 Figure 1