Cr3+-free broadband near-infrared phosphors NaAl5O8:Fe3+

Broadband near-infrared spectroscopy has become a research hotspot because it can be used in many fields. For the preparation of near-infrared phosphors, non-toxic and harmless Fe3+ is an excellent activator. Herein, Fe3+-activated NaAl5O8 near-infrared phosphors were prepared, the phase and the properties of luminescence were analyzed. Under the excitation of 346 nm, the NaAl5O8:Fe3+ phosphors emit 600–850 nm light, 754 nm is the emission peak of the sample. The optical band gap of NaAl5O8:Fe3+ was evaluated. It was observed that the optical band gap of sample narrows as the doping concentration of Fe3+ increases. By measuring the emission spectra at 303–463 K, it is evident that the emission intensity remains 83.1 % of 303 K at 423 K. It shows that the thermal stability of the sample is good. The luminescence of the sample after soaking in deionized water for 0–10 h were observed. These results indicate that the NaAl5O8:Fe3+ samples have application prospects in some high temperature or wet fields. Moreover, the security ink was prepared by using NaAl5O8:Fe3+, indicating that the sample can be used in the field of anti-counterfeiting.