No abstract

Sr3−2xCexNaxAlO4F phosphors were synthesized by a high temperature solid-state reaction method, and their luminescence properties were investigated. Ce3+ ions occupy two different Sr2+ sites in these phosphors, and the different emissions derived from the two luminescent centers are discussed in terms of the matrix structure. The site occupancy and energy-transfer process give rise to the concentration-dependent luminescence behaviors, and the emission color may be tuned in a large color gamut from blue-green to yellow-green by controlling the Ce3+ concentration. Because the phosphors exhibit a strong absorption in the range of near-UV to blue spectral region, the phosphors were utilized to fabricate the phosphor-converted light emitting diodes. The results show that the phosphors Sr3−2xCexNaxAlO4F have potential applications in light emitting diode (LED) devices.

Near-infrared (NIR) persistent luminescence (PersL) materials are attractive multifunctional-material-platforms to real-time-required studies and applications in chemistry and biomedicine. However, the inefficient charging by low-irradiance, noncoherent, and high-tissue-penetration red−NIR light restricts their developments and applications in situ, such as long-term tracking, whole-body, and deep-tissue bioimaging. To address this issue, we develop a novel Cr 3+ -activated Na 0.5 Gd 0.5 TiO 3 NIR-PersL material with perovskite structure. It shows over 100 times stronger PersL intensity than those of the best known Cr 3+ -doped phosphors, including