Dual-crystal-field luminescence in Fe3+-Doped Sr4Al14O25for high-sensitivity near-infrared thermometry and anti-counterfeiting

Luminescence thermometry has emerged as a promising non-invasive technique for precise temperature measurement, particularly in fields such as microelectronics, optoelectronics, and biomedicine. Here, we report the development of a novel dual-mode near-infrared (NIR) luminescence thermometer based on Fe3+-doped Sr4Al14O25 (SAO). By integrating experimental and first-principles computational approaches, we demonstrate that Fe3+ ions occupy both tetrahedral and octahedral sites within the SAO host material, yielding distinct broad band emissions with peaks at 752 nm and 812 nm. The temperature-dependent fluorescence intensity ratio (FIR) of these emissions exhibits a maximum relative temperature sensitivity of 2.72 % K−1, making this material a highly promising candidate for precision temperature sensing. Furthermore, the material's potential for application in anti-counterfeiting technologies is explored, suggesting its versatility in multifunctional optoelectronic devices. This work not only advances the understanding of Fe3+-doped NIR emitting materials but also opens new avenues for their practical applications in diverse fields.