Sensitization of lanthanide-based phosphors by transition metals for high-brightness tunable thermometers (SensiTherm)

• Applicant: Professor Dr.-Ing. Frank Beyrau, since 3/2022
• Subject Area: Technical Thermodynamics ; Synthesis and Properties of Functional Materials
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426574030

• Final Report Year: 2024

Final Report Abstract

Luminescence thermometers based on lanthanide ions can provide robust remote temperature measurements in systems spanning a wide range of scales, from nanothermometry in biomedical applications to surface temperature imaging on engine components. This project explores a path to design bright and temperature sensitive lanthanide-based luminescence thermometry which is the addition of optically active transition metals ions. Three systems are explored Mn4+/Tb3+, V3+/Eu3+ and Cr3+/(Nd3+,Er3+): In each system, the transition metal plays a different role in creating a temperature sensitive response. Low cost imaging systems exploiting those thermometric responses are also proposed and demonstrated. To address brightness, a method to determine the absolute emission intensity of co-doped particles based on particle dispersion is applied. It reveals for example, that co doping with Cr3+ can yield a 30-fold enhancement of the emission intensity of Nd3+ in YAG under broad white light excitation. To gain further insight in the sensitisation process, a method to determine the absorption cross section of the sensitizer ion is proposed and validated. It combines absolute intensity and quantum efficiency measurements of the activator emission upon excitation in the sensitizer band. Different enhancement factors are observed when probing the powder in the bulk and in dispersions, and the dopant concentration which provides the highest brightness is found to significantly differ. By comparing measured brightness in the bulk powder; quantum efficiency and absorption coefficient, it is found that the number of absorbed photons in bulk powders is not directly proportional to the absorption cross section of the luminescent particles. This sublinear dependence follows an exponent of approximately 0.4. In conclusion, when developing bright thermometers, the optimisation process should systematically consider measurements performed in the thin optical state, for example with the methods developed in this project.

Publications

• Thermochromic Luminescent Nanomaterials Based on Mn4+/Tb3+ Codoping for Temperature Imaging with Digital Cameras. ACS Applied Materials & Interfaces, 12(39), 44039-44048.
  Piotrowski, Wojciech; Trejgis, Karolina; Maciejewska, Kamila; Ledwa, Karolina; Fond, Benoit & Marciniak, Lukasz
  
• Two line excitation 2D phosphor thermometry using low power LEDs. In GRC Connects: Laser Diagnostics in Energy and Combustion Science; online ( 2020).
  Dalipi, Linda
  
• Self‐Referenced Temperature Imaging with Dual Light Emitting Diode Excitation and Single‐Band Emission of AVO4:Eu3+ (A=Y, La, Lu, Gd) Nanophosphors. Advanced Photonics Research, 3(6).
  Piotrowski, Wojciech; Dalipi, Linda; Elzbieciak-Piecka, Karolina; Bednarkiewicz, Artur; Fond, Benoit & Marciniak, Lukasz
  
• The role of Cr3+ and Cr4+ in emission brightness enhancement and sensitivity improvement of NIR-emitting Nd3+/Er3+ ratiometric luminescent thermometers. Journal of Materials Chemistry C, 9(37), 12671-12680.
  Piotrowski, W.; Dalipi, L.; Szukiewicz, R.; Fond, B.; Dramicanin, M. & Marciniak, L.
  
• A 2D temperature imaging system based on two low-power low-cost LEDs for excitation and a single low speed camera for detection_. In International Conference on Phosphor Thermometry, Magdeburg, Germany ( 2022).
  Dalipi, Linda
  
• Cr3+ ions as an efficient antenna for the sensitization and brightness enhancement of Nd3+, Er3+-based ratiometric thermometer in GdScO3 perovskite lattice. Journal of Alloys and Compounds, 923, 166343.
  Piotrowski, W.M.; Maciejewska, K.; Dalipi, L.; Fond, B. & Marciniak, L.
  
• Luminescence particle brightness assessment in diluted and agglomerated states . In 21th International Conference on Dynamical Processes in Excited States of Solids; Wroclaw Poland ( 2022).
  Dalipi, Linda
  
• Investigating the role of particle aggregation state in phosphor emission brightness. In International Conference on Luminescence, Paris, France ( 2023).
  Dalipi, Linda