Functional phosphors with shortwave infrared (SWIR) persistent luminescence have attracted an ever-increasing interest from scientists owning to the self-sustainable emission for deeper tissue penetration, real-time monitoring, and nondestructive analysis. In this work, we report for the first time on the broadband wavelength-tunable SWIR luminescence and photochromism properties of divalent nickel-doped yttrium aluminum gallium garnet solid solutions. The crystal-field-driven wavelength-tunable superbroad band emission within SWIR wavelength region, attributed to the 3 T 2 ( 3 F) → 3 A 2 ( 3 F) transitions of the Ni 2+ ions, can be controllably adjusted. The observation of SWIR longpersistent luminescence also can be modified by bandgap engineering via the simple adjustment of the Ga/Al ratio. Besides, the accompanied observation of photochromism, i.e., the reversible body color change by alternative UV and visible illumination/ heating treatment, shows robust fatigue resistance. The nature of traps, color centers, and trapping and releasing of electrons are studied by electron paramagnetic resonance and thermoluminescence. Finally, an energy level schematic diagram is established to discuss the SWIR persistent luminescence and photochromism mechanisms in detail. This work opens an avenue to motivate researchers to rationally design and purposely explore novel bifunctional phosphors with broad-band wavelength-tunable SWIR persistent luminescence and photochromism.
A dual‐emission (UV/Visible) phosphor SrZrO3: Pr3+ was prepared by a high‐temperature solid‐state reaction method. The afterglow including ultraviolet (UV) and visible region which originated from self‐trapped excitons and f–f transitions in Pr3+ was first observed after the short UV‐irradiation. All as‐prepared phosphors were studied systematically by X‐ray diffraction, photoluminescence (PL) spectra, decay curves, long afterglow spectra (LAG), and thermoluminescence (TL) glow curves. The PL intensity and the performance of afterglow are dependent on the concentration of Pr3+ ions. The optimal concentration of Pr3+ ions for the brightest PL emission and the best afterglow characteristic were experimentally to be 0.5% and 0.4%, respectively. The different mechanisms for concentration quenching in both cases were discussed. A model was proposed on the basis of experimental results to discuss the mechanism of LAG in SrZrO3: Pr3+ in detail.
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