Broadband NIR-II phosphors with Cr4+ single activated centers based on special crystal structure for nondestructive analysis

Realizing Ultrabroadband NIR-II Emission and Wide-Range Wavelength Tuning in Cr4+-activated ABO2 (A = Li, Na; B = Al, Ga) Phosphors

“…Using the above single-exponential equation fitting, the fluorescence lifetimes of LiAlO 2 : 0.03Cr 4+ and NaGaO 2 : 0.03Cr 4+ are calculated to be τ 1 = 36.133 μs and τ 2 = 4.652 μs, respectively. The obtained fluorescence lifetimes of the two phosphors are on the order of microseconds, which is consistent with the characteristics of Cr 4+ luminescence . It can be seen that compared to LiAlO 2 : Cr 4+ , the fluorescence lifetime of NaGaO 2 : Cr 4+ has decreased, indicating that NaGaO 2 : Cr 4+ exhibits stronger nonradiative transitions at room temperature.…”

“…This indicates that the cation substitutions of Na → Li and Ga → Al cause the tetrahedron to twist and expand, degrading the symmetry of the structure and inducing phase transition. Therefore, unlike the crystal structure of LiAlO 2 , NaAlO 2 and NaGaO 2 belong to the Pna2 1 (33) space group in the orthorhombic system. Their crystal structures are shown in Figure 1e and f.…”

“…The obtained fluorescence lifetimes of the two phosphors are on the order of microseconds, which is consistent with the characteristics of Cr 4+ luminescence. 33 It can be seen that compared to LiAlO 2 : Cr 4+ , the fluorescence lifetime of NaGaO 2 : Cr 4+ has decreased, indicating that NaGaO 2 : Cr 4+ exhibits stronger nonradiative transitions at room temperature. As mentioned in Section 3.2.2, the fwhm of NaGaO 2 : Cr 4+ is wider than that of LiAlO 2 : Cr 4+ , indicating stronger electron phonon coupling and an increased probability of nonradiative transitions, which corresponds to the shortening of the fluorescence lifetime.…”

Valence state control of Cr4+-activated Li2SrGeO4for NIR-II light source to distinguish deuterium and non-deuterium reagents

“…4b), which is an improvement compared to the 43.66% of Li 2 ZnGeO 4 . 44 The FWHM gradually expands from 208 nm to 230 nm as the temperature rises, which is attributed to the weaker crystal field at the higher temperature (Fig. 4c).…”

Achieving Broadband NIR Emission in Fe3+‐Activated ALaBB′O6 (A = Ba, Sr, Ca; B–B′ = Li–Te, Mg–Sb) Phosphors via Multi‐Site Ionic Co‐Substitutions

“…For example, water shows strong absorption near 970 nm, while ethanol is relatively weak. [48][49][50] In this experiment, we compare the infrared transmission spectra of water and ethanol using the phosphor CaLaMgSbO 6 : 0.6%Fe 3+ as the infrared light source (under 310 nm excitation). As shown in Figure 7a, NIR light passes through the cuvette, and the corresponding transmission spectrum is recorded by the GaInN NIR monitor.…”