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NIR luminescent materials are widely available for biological applications, and the NIR emitting of Ho3+ ions has received widespread attention in the second biological window. In this work, Ca14Zn6Ga10O35 : Mn4+,Ho3+ luminescent materials were synthesized using a high temperature solid state method. Optical properties and energy transfer mechanisms have studied in detail. Upon UV‐vis light excitation, the Mn single doped Ca14Zn6Ga10O35 phosphors exhibit deep red and NIR emission centered at 712 and 1151 nm assigned to Mn4+ and Mn5+, respectively. Another stronger NIR emitting peaked at 1195 nm occurs when the Ho3+ ion is co‐doped into Ca14Zn6Ga10O35 : Mn4+. The energy transfer from Mn4+ to Ho3+ ion is performed through a resonant type by a dipole‐dipole interaction mechanism. In addition, the thermal stability of Ca14Zn6Ga10O35 : Mn4+,Ho3+ phosphor has been investigated, and the NIR emission of Ho3+ ion maintains more than half the strength at 423 K. The findings indicate that the as‐prepared Ca14Zn6Ga10O35 : Mn4+,Ho3+ luminescent materials hold promise for potential applications in the second biological window. [ABSTRACT FROM AUTHOR]

Abstract: An abnormal trap distribution and coordination geometry‐dependent multi‐band emission are discovered in chromium‐doped aluminates. The multi‐band and broadband persistent luminescence from 650–1100 nm peaking at 688 and 793 nm from Cr3+‐doped SrAl12O19 is systematically studied via structural and spectroscopic analysis. Solid state nuclear magnetic resonance allows the visualization of various coordination configurations in SrAl12O19, thus offering the possibility of tailoring the local geometry of the emission center to trigger the control of the spectral parameter. Deep tissue ex vivo and in vivo imaging in mice both demonstrate that multi‐band‐emissive SrAl12O19:Cr3+ shows superior, high‐quality near‐infrared (NIR) bio‐imaging in the biological transparency window compared to single band‐emissive (with emission only at 688 nm) SrAl2O4:Cr3+, although SrAl2O4:Cr3+ has a higher luminescent intensity and longer duration at 688 nm. Moreover, by measuring the thermoluminescence spectra the driving force of carrier release is discovered to be only from the deep trap (the depth is > 1 eV), which is different from the generally accepted shallow‐dependent afterglow‐emitting process. These findings pave the way for opening a vista of possible avenues for the enhancement of signal‐to‐noise ratio, the improvement of imaging quality, as well as the understanding of the trapping and de‐trapping process in long‐persistent phosphors. [ABSTRACT FROM AUTHOR]

• Optical stimulated luminescence is observed from SrAl 12 O 19 : Mn2+, Gd3+. • The detrapping of electrons is operable by controlling the IR laser. • An optical information storage that integrate a writing-storing-readout-erasing-rewriting is realized. In the current big data era, state-of-the-art optical data storage has become a front-runner in competing data storage technologies. In this work, we propose an information storage prototype using optical stimulated luminescent phosphor of SrAl 12 O 19 : Mn2+, Gd3+, which converts the photon into trapped electrons and partially releases them in a form of luminescence when irradiated by infrared irradiation, rendering an optical information storage ability. Information storage can be realized in both graphical and digital formats. In this way, graphical patterns can be stored and rejuvenated by infrared irradiation, and a set of digital data is recorded step by step by a home-make decoding system, completing an optical data reading process. This work provides a practical example for future application of writing-storing-readout-erasing-rewriting integrated optical information storage. [ABSTRACT FROM AUTHOR]

The persistent phosphor Y 3 Ga 5 O 12 : 0.5%Cr3+ (YGG:C) and Y 3 Ga 5 O 12 : 0.5%Cr3+, 0.5%Si4+ (YGG: CS) were synthesized by traditional solid-state reaction. Y 3 Ga 5 O 12 was employed as a host to take advantage of its abundant intrinsic traps. Moreover, Si4+ dopant was introduced to precisely tailor the trap distribution so that the initial persistent brightness of YGG: CS is around 7 times higher than that of YGG: C. The photo-stimulated traps were firstly found in YGG: CS, and the effective number of photo-stimulation was confirmed to be several hundreds. The broad emission band (650–950 nm) of YGG: CS and useful stimulated source (655 nm) are all located in the biological window (650–1350 nm). In this work, pork tissue imaging experiments were performed by means of the hundreds of hours persistent luminescence and hundreds of times photo-stimulated property of YGG: CS. Image 1 • The persistent property of the YGG: Cr3+ was improved for more than sevenfold. • Afterglow of YGG: Cr3+, Si4+ reappear through low-energy photo-stimulation. • The efficiency photo-stimulation process can be repeated hundreds of times. • Photo-stimulation dependence YGG: Cr3+, Si4+ showed great bio-imaging property. [ABSTRACT FROM AUTHOR]

Abstract A dual-emission long persistent luminescence phosphor SrZrO 3 : Yb3+ is synthesized through a conventional high-temperature solid-state reaction method. A combined experiment and first-principles methods are carried out to study the inner link between the electronic structures and spectroscopic characteristics of SrZrO 3 : Yb3+ phosphor. The calculation shows that the incorporation of Yb3+ ions into SrZrO 3 lattice can be done through substituting Yb3+ ions for Sr site. It is found that vacancy defects of SrZrO 3 : Yb3+ system easily produce around the doping positions. Especially, the oxygen vacancies, which are deduced as the intrinsic vacancy defect, are responsible for the persistent luminescence in SrZrO 3 : Yb3+ phosphor. The persistent luminescence of SrZrO 3 : Yb3+ consists of two parts: near-ultraviolet persistence originate from self-trapped excitons of host, and near-infrared one stems from 2F 5/2 → 2F 7/2 transitions of Yb3+. The photoluminescence and persistent performance are studied as function of the concentration of Yb3+ ions. The optimal concentration of Yb3+ ions for the photoluminescence emission and long persistent luminescence are both approximately 2.5%. The long persistent luminescence mechanism for SrZrO 3 :Yb3+ is illuminated on the basis of photoluminescence and first-principle calculation results. Highlights • SrZrO 3 : Yb3+ presents a dual-emission (NUV and NIR) long persistent luminescence. • Oxygen vacancies in SrZrO 3 :Yb3+ play an important role in the persistent luminescence. • The PL and calculation results confirm the persistent mechanism of SrZrO 3 :Yb3+. [ABSTRACT FROM AUTHOR]