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Title: Interplay of Optical Traps and Vibronic Thermalization Governing Mn²⁺ Luminescence in Ca₁₉Ce(PO₄)₁₄: Implications for Temperature Sensing and Thermal Threshold Indicator

Authors: Y. Abe, M. Szymczak, J. Zeler, R. Szukiewicz, L. Marciniak*

Journal: Laser & Photonics Reviews

DOI: 10.1002/lpor.71411

The development of advanced luminescent thermometric materials requires the identification of novel mechanisms capable of inducing temperature-dependent changes in the spectroscopic properties of phosphors. In response to this need, the present work demonstrates a cooperative effect involving the thermalization of the ⁴T₁(⁴G) -level components of Mn²⁺ ions and trap → ⁴T₁(⁴G) energy transfer in Ca₁₉Ce(PO₄)₁₄:Mn²⁺. This interplay results in a simultaneous enhancement of the ⁴T₁(⁴G) → ⁶A₁(⁶S) emission band intensity accompanied by a blue shift of its spectral position with increasing temperature. This phenomenon can be effectively utilized for temperature sensing and imaging applications. Furthermore, the distinct thermal responses of Ce³⁺ and Mn²⁺ luminescence enable not only the determination of the luminescence intensity ratio (S_R = 4.5% K⁻¹), but also the development of a luminescent indicator for detecting the crossing of a threshold temperature using the RGB channels of a standard camera. Importantly, the activation temperature of the signal in the G channel, which is governed by the Mn²⁺ ion concentration, provides a means to tune the threshold temperature of the sensor. This allows for precise adjustment of the sensor performance to meet specific application requirements.

This work was supported by the Foundation for Polish Science under the First Team FENG.02.02-IP.05-0018/23 project with funds from the 2nd Priority of the Program European Funds for Modern Economy 20212027 (FENG).