(Invited) On Dilemmas of Band Gap Engineering in Luminescence Thermometers

Abstract

Luminescence thermometry and 2D imaging by means of luminescence thermometric phosphors are of growing interest as these non-contact and almost non-invasive techniques may possibly offer important advantages in some areas of applications. The requirements such thermometers have to fulfill are quite dependent on considered application. It is obvious that bio and medical applications points on different parameters than measurements in cryo range and measuring high temperatures point on yet different needs. Nevertheless, high-sensitivity and low inaccuracy are always appreciated, as well as chemical stability in conditions the thermometers are used. One of the limitations of luminescence thermometers proposed up to data is the limited range of temperatures they may measure. Clearly, some applications do not need a broad range of a thermometer usability. On the other hand, presenting a good performance over a wide range of temperatures luminescence thermometer could be considered a versatile “all-purpose” device. This might open a door for truly broad usage of such phosphors. Trying to deliberately manage the performance of luminescence thermometers for broad-range temperature measuring we paid attention into the band gap engineering as a tool to achieve the goal. In this presentation we shall focus on Sr2(Ge,Si)O4:0.05%Pr powders with different Ge:Si ratio to adjust the host lattice band gap and consequently to manage the thermometer performance, see the figure attached. Basing on the lesson learned from Sr2(Ge,Si)O4:0.05%Pr we shell try to draw more general conclusions too. This research was supported by Polish National Science Centre upon the grant #UMO-2017/25/B/ST5/00824 and by the Portuguese project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019. Figure 1