科研之友
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摘要
Near-infrared (NIR) II region (1000-1700 nm) lighting sources possess special potential for temperature sensing and quantitative composition analysis. However, it is a challenge to tune the luminescence toward such long wavelength NIR-II emission. Herein, Cr4+ ions occupation is designed and verified in olivine-type CaYGaO4 as [CrO4] tetrahedron by site occupancy confinement. Under 620 nm red light excitation, the phosphors display broadband NIR-II emission centered at 1330 nm with a full width at half maximum (FWHM) of 233 nm, resulting from spin-allowed T-3(2) to (3)A(2) transition of Cr(4+ )ions in T(d )symmetry. The optical thermometry application is demonstrated by decoding the spectral shift and decay times varying with temperature, and the maximum relative sensitivities are 5.82% and 0.78% K-1, respectively. Furthermore, a flexible film containing CaYGaO4:Cr4+ is fabricated to implement the non-invasive detections of fillet temperature and NH3 concentration in ammonia. This work represents a step toward developing next-generation NIR-II luminescence materials and widens non-invasive detection applications.
