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.

Automated summary

Broadband near-infrared spectroscopy is a research hotspot used in various fields. Fe3+ is an excellent activator for the preparation of near-infrared phosphors. In this study, Fe3+ activated NaAl5O8 near-infrared phosphors were prepared and analyzed for their phase and luminescence properties. The NaAl5O8:Fe3+ phosphors emitted light at 600-850 nm with an emission peak at 754 nm under the excitation of 346 nm. The sample showed good thermal stability and application prospects in high temperature or wet fields. Additionally, it was used in the preparation of security ink for anti-counterfeiting purposes.