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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]