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Technological progress has accelerated the researches into broadband near‐infrared (NIR) luminescent materials as next‐generation intelligent NIR light sources; however, poor thermal stability restricts the applications of NIR phosphors. Herein, new insights into Cr3+‐activated NIR phosphors with improved thermal stability are provided. The photoluminescence intensity originating from the 4T2→4A2 broadband emission of CaLu2Al4SiO12:Cr3+ (CLAS:Cr) with optimal electron occupation (4T2/2E) increases up to 118% at 475 K compared with that at room temperature, which is the best for Cr3+‐activated broadband NIR phosphor. Accordingly, new ideas for the design of thermally stable phosphors are proposed by optimizing the thermal population between 4T2 and 2E states and electron migration from 2E to 4T2 state. Finally, multifunctional applications of CLAS:Cr in NIR fluorescence intensity ratio thermometry, X‐ray detection, NIR phosphor‐converted light‐emitting diodes, and bio‐imaging are demonstrated. [ABSTRACT FROM AUTHOR]

The phosphors BaMgAl10 O17: Eu2+ ( BAM) were prepared by a high-temperature solid-state reaction method using BaCO3, MgO, Eu2 O3, and Al2 O3 with different (α, θ, and γ) phases. The reaction processes and final products were investigated and compared using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and VUV- UV-Vis spectra, indicating that Al2 O3 has minimum influence on the crystallinity, morphology, and luminescence of BAM. [ABSTRACT FROM AUTHOR]

The phosphors BaMgAl10 O17: Eu2+ ( BAM) were prepared by a high-temperature solid-state reaction method using BaCO3, MgO, Eu2 O3, and Al2 O3 with different (α, θ, and γ) phases. The reaction processes and final products were investigated and compared using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and VUV- UV-Vis spectra, indicating that Al2 O3 has minimum influence on the crystallinity, morphology, and luminescence of BAM. [ABSTRACT FROM AUTHOR]

Research on lithium compounds has attracted much attention nowadays. However, to elucidate the precise structure of lithium compounds is a challenge, especially when considering the small ions that may be transferred between the interstitial voids. Here, the discovery of reduced local symmetry (symmetry breaking) in small domains of Li2SrSiO4 is reported by employing Eu3+ as a spectroscopic probe, for which X‐ray, neutron, and electron diffraction have confirmed the average long‐range structure with the space group P3121. However, luminescence shows a lower local symmetry, as confirmed by the extended X‐ray absorption fine structure. By considering the reduced symmetry of the local structure, this work opens the door to a new class of understanding of the properties of materials. [ABSTRACT FROM AUTHOR]