The experimental and theoretical research on the near infrared luminescent property of KAl11O17:Fe3＋ and RbAl11O17:Fe3＋

The luminescent materials with unique near-infrared (NIR) emission have attracted intensive attentions due to their potential broad applications. As an alternative to current widely used lanthanide ions or Cr3+ doped phosphors, we developed a new series of KAl11O17:Fe3+ (KAO:Fe3+) and RbAl11O17:Fe3+ (RAO:Fe3+) NIR luminescent materials, both of which exhibit a broad band emission from 650 to 850 nm with the maximum at around 770 nm, due to the electronic transition from 4T1 (4G) to 6A1 (6S) of Fe3+ ion. The distribution of Fe3+ at Al3+ sites and the energy levels of Fe3+ are estimated by the First-Principles calculations. To explore the potential applications of these phosphors, the thermal quenching resistance and tissue penetration performance of K/RAO:Fe3+ are investigated. The results show that the emission intensity of RAO:Fe3+ at 150 °C (423 K) maintains 95% of that at room temperature, implying a good thermal quenching resistance. KAO:Fe3+ can be used as a candidate for NIR luminescence thermometry, since its emission intensity is very sensitive to the temperature. In addition, the NIR emission of KAO:Fe3+ can penetrate pork tissue of 6 mm thickness. Our findings here may motivate the design of Fe3+ doped NIR luminescent materials and promote their applications in future.