(Invited) Combining the 5d→4f and 4f→4f Luminescence of Lanthanides for High-Quality Broad-Range Luminescence Thermometry

Abstract

Accurate and sensitive remote temperature measurement is required in a growing number of existing and emerging applications. As the technology advances and nanotechnology enters still new fields, the size of objects whose temperature needs to be controlled gets smaller and the non-contact temperature reading is the only reasonable approach. Luminescence thermometry is believed to become the technology of choice for such purposes, as it is resistant to disturbances by an electromagnetic field and the sensitivity and accuracy of measurements may be tuned for the specific requirements. Thus, whether it comes to reading temperature at cryo-range, around the room, or at high temperatures, one may design a luminescent thermometer offering high-quality measurements. This is not to say that such designing is easy to do. Even under laboratory conditions, highly-sensitive and accurate luminescent thermometers are not that frequent.Additional problems appear when it comes to measurements over a broad range of temperatures. At first, the basic physics of luminescence processes are not conducive to the design of a luminescence thermometer offering very sensitive and accurate measurements over a broad range of temperature (a few hundred degrees, for example). On the other hand, wide-range luminescence thermometers are of interest for such important fields as aviation and space industries. Fast, accurate, and credible measurements of quickly changing temperatures are of special importance in these areas.In this presentation, we shall report a new approach toward wide-range high-quality luminescence thermometry. Phosphors activated with either Pr3+ or Eu2+ will be examined for that purpose. Both these ions are capable of generating two types of emissions: (i) intra-configurational 5f→4f and inter-configurational 4f→4f ones. We shall prove that such phosphors may offer both broad-range and high-accuracy and high-sensitivity temperature measurements. Furthermore, we will demonstrate that the sensitivity of such sensors may be deliberately tuned to reach its maximum at temperatures where it is most needed. A few examples of such phosphors will be discussed and possible expectations for further development using this approach will be discussed.This research was supported by the Polish National Science Center (NCN) under the grant #UMO-2018/29/B/ST5/00420. Figure 1