J. Eur. Opt. Society-Rapid Publ. 2026, 22, 18 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2026010 Available online at: https:// jeos. edpsciences. org
EOSAM 2025 Guest editors: Omar El Gawhary, Stefan Witte, Ignacio Moreno
Journal of the European Optical Society-Rapid Publications
SHORT COMMUNICATION
Luminescent thermal history sensing potential in Pr 3 +-activated YAG matrix Oskar Bogucki 1, 2,*
, Marcin Kaczkan 1, Anna Kozłowska 2, Aleksandra Pantoł-Boczon 2, 3, and Agnieszka Malinowska 2
1 |
Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662, Poland |
2 |
Łukasiewicz Research Network Institute of Microelectronics and Photonics, al. Lotników 32 / 46, Warsaw 02-668, Poland |
3 |
Warsaw University of Technology, Faculty of Chemistry, al. Noakowskiego 3, Warsaw 00-664, Poland |
Received 30 December 2025 / Accepted 4 February 2026
Abstract. In this study, it was demonstrated that Pr 3 +-doped YAG powder can record thermal history in the temperature range of the template provided by 1100 – 1600 ° C. Upon heating, the material undergoes irreversible structural phase transformations( YAM? YAP? single-phase YAG) induced by 2 h of thermal annealing, leading to permanent changes in both the emission intensity and the excited-state lifetime of Pr 3þ ion. Temperature can be determined using two approaches: by analyzing the intensity ratio of the 3 P 0! 3 H 4 and 1 D 2! 3 H 4 emission bands, which increases linearly over 1300 – 1600 ° C with a sensitivity of
0.001 ° C �1, and by measuring the luminescence decay time of the 1 D 2! 3 H 4 transition, which decreases linearly over 1100 – 1600 ° C with a sensitivity of 0.38 ls ° C �1. The combination of both methods enables durable and quantitative tracking of the material’ s thermal history, confirming the suitability of YAG: Pr 3þ powders for high-temperature diagnostics, thermal mapping, and monitoring of industrial processes.
Keywords: YAG: Pr 3 +, Thermal history sensor, Luminescence, Optical thermometry.
1 Introduction
Temperature is a key thermodynamic parameter in industrial and research applications [ 1 ]. At high temperatures, conventional measurement techniques such as thermocouples, resistance sensors, or pyrometers suffer from limitations related to physical contact and restricted material durability [ 2 – 4 ]. Moreover, rare-earth-doped optical fibers are typically unstable above ~ 1100 ° C, limiting their use under extreme conditions [ 5 ]. Here, luminescence-based techniques offer a viable alternative. These methods are based on the emission of RE 3 + ions embedded in crystalline hosts such as YAG, which undergo predictable and irreversible structural transformations after 2 h of thermal annealing. These transformations permanently modify the luminescence properties, enabling the material to function as a fluorescent thermal history sensor( THS) [ 6 ]. Pr 3 + ions are particularly attractive activators due to their specific energy structure, enabling a broad excitation range and intense visible emission [ 7, 8 ].
In the Y 2 O 3 – Al 2 O 3 system, increasing temperature induces a sequence of phase transitions – from YAM to
* Corresponding author: oskar. bogucki. dokt @ pw. edu. pl
YAP and finally to single-phase YAG above ~ 1600 ° C [ 9 ]. Each phase provides a distinct local crystal field for Pr 3 + ions, modifying electronic levels, phonon interactions, and thus luminescence properties [ 10 ]. Luminescence intensity [ 11 ] and lifetime [ 12 ] are strongly determined by the local crystal structure, which evolves irreversibly depending on both the temperature and duration of thermal exposure. Therefore, these changes can be exploited to construct a fluorescent THS. Crucially, these changes originate from irreversible phase transitions, enabling permanent recording of past thermal exposure and forming the basis of THSs, which allow reconstruction of the maximum temperature experienced by a material [ 10, 13 ]. Compared to temperature-indicating paints, phosphor powders offer superior chemical stability, quantitative readout, and applicability to complex geometries [ 13 ].
In the present work, YAG: 1 % Pr powder was investigated as a potential THS material. The analysis comprised two detection approaches based on the fluorescence intensity ratio( FIR) as well as an analysis of luminescence decay times. The FIR can be defined either as a comparison of the same emission peak measured at different temperatures [ 14, 15 ] or, more commonly in optical thermometry, as the ratio of two distinct emission peaks measured at the same
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