Europium Ions Self‐Reduction Benefiting from AlO<sub>4</sub>/Si(Al)O<sub>4</sub> Network Structure for Multimode Optical Thermometry Manometry
Ruiying Lu, Xinyao Zhang, Yuanyuan Fang, Xue Wu, Mochen Jia, Kai Wang, Jinfei Wu, Qian Li, Zhen Sun
Abstract
Abstract Mixed‐valence europium ions‐activated phosphors have distinct advantages in color modulation, dynamic anti‐counterfeiting, and optical sensors. Nevertheless, it is still a challenge to obtain mixed‐valence europium ions in single compounds by facile self‐reduction. Herein, the crystal structure of a 3D hexagonal network formed by SiO 4 /AlO 4 tetrahedra is demonstrated to play a significant role in the spontaneous reduction of Eu 3+ to Eu 2+ based on SrAl 2 Si 2 O 8 , Sr 2 SiO 4 , SrAl 2 O 4 hosts. The crystal field theory and Judd‐Ofelt theory provide a deeper understanding of Eu 2+ and Eu 3+ luminescence behavior, namely, the low energy spectra of Eu 2+ are more easily observed in crystal structure with high polarizability and octahedral coordination, whereas the spectra properties of Eu 3+ are affected by the symmetry of local environment and crystal rigidity. For SrAl 2 Si 2 O 8 : 0.02Eu 2+ /Eu 3+ , multi‐mode thermometry is explored in terms of the luminescence intensity ratio (LIR) of Eu 2+ /Eu 3+ , luminescence intensity (LI) and full‐width at half maximum (FWHM) of Eu 2+ with maximal relative sensitivity reaching 3.83% K −1 . This study presents the first exploration of optical manometry based on the LIR mode of Eu 2+ /Eu 3+ with excellent sensitivity ( S r = 18.13% GPa −1 ). This work not only provides a novel strategy for the design of mixed‐valence ions‐activated materials but also constructs promising optical thermometry, and manometry candidates.