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Long wavelength near-infrared (LWNIR) light (1000–2000 nm) has great potential in the field of biomedical imaging, non-visual illumination, and non-destructive detection. However, currently, such as Cr3+ and Ni2+ can achieve broadband NIR emission, but their emission wavelengths are under 1600 nm with limited tunability. Herein, we developed Ni2+-doped (Sr/Ba)2MgMoO6 double perovskite molybdate-based solid-solution LWNIR phosphors via the high-temperature solid-state method. By adjusting the ratio of Sr/Ba in the phosphors, NIR emission peaks can be tuned from 1400 nm to 1610 nm under 400 nm excitation. Based on the analysis of crystal structures and luminescence characteristics and simulation results, we propose that the main reason for the shift of NIR peak emission is the difference in charge density and symmetrical polarizability of Ni2+ ions in the center of the octahedron due to the crystal structural changes of the matrices from tetragonal Sr2MgMoO6 to cubic phase Ba2MgMoO6. We constructed a LWNIR pc-LED with the optimal phosphors and a commercially near-ultraviolet LED chip, which efficiently emitted LWNIR light. The utility of this new LWNIR pc-LED as the NIR light source for non-invasive imaging and non-destructive detection of biological and non-biological objects was demonstrated. [ABSTRACT FROM AUTHOR]

This study explores the integration of X‐ray‐induced photochromism and photoluminescence in a single material, offering innovative multi‐mode applications in optical memory, anti‐counterfeiting, and X‐ray detection and imaging. The photochromic phosphor LiAlSi2O6:Sm3+ is synthesized, which undergoes a color change from white to dark green under bright field conditions and displays orange photoluminescence in dark field conditions after X‐ray exposure due to defect formation. The phosphor shows accelerated bleaching and recovery under 473 nm laser stimulation. The distinct X‐ray‐induced color contrast and luminescence intensity modification in LiAlSi2O6:Sm3+ highlight its potential in advanced luminescent material design. Moreover, a LiAlSi2O6:Sm3+‐based flexible film demonstrates "dual‐mode" 3D X‐ray imaging and detection capabilities, paving the way for future X‐ray detecting and imaging device research. [ABSTRACT FROM AUTHOR]

Photochromic glass shows great promise for 3D optical information encryption and storage applications. The formation of Ag nanoclusters by light irradiation has been a significant development in the field of photochromic glass research. However, extending this approach to other metal nanoclusters remains a challenge. In this study, we present a pioneering method for crafting photochromic glass with reliably adjustable dual‐mode luminescence in both the NIR and visible spectra. This was achieved by leveraging bimetallic clusters of bismuth, resulting in a distinct and novel photochromic glass. When rare‐earth‐doped, bismuth‐based glass is irradiated with a 473 nm laser, and it undergoes a color transformation from yellow to red, accompanied by visible and broad NIR luminescence. This phenomenon is attributed to the formation of laser‐induced (Bi+, Bi0) nanoclusters. We achieved reversible manipulation of the NIR luminescence of these nanoclusters and visible rare‐earth luminescence by alternating exposure to a 473 nm laser and thermal stimulation. Information patterns can be inscribed and erased on a glass surface or in 3D space, and the readout is enabled by modulating visible and NIR luminescence. This study introduces a pioneering strategy for designing photochromic glasses with extensive NIR luminescence and significant potential for applications in high‐capacity information encryption, optical data storage, optical communication, and NIR imaging. The exploration of bimetallic cluster formation in Bi represents a vital contribution to the advancement of multifunctional glass systems with augmented optical functionalities and versatile applications. [ABSTRACT FROM AUTHOR]

Lanthanide‐based NIR‐II‐emitting materials (1000–1700 nm) show promise for optoelectronic devices, phototherapy, and bioimaging. However, one major bottleneck to prevent their widespread use lies in low quantum efficiencies, which are significantly constrained by various quenching effects. Here, a highly oriented (222) facet is achieved via facet engineering for Cs2NaErCl6 double perovskites, enabling near‐complete suppression of NIR‐II luminescence quenching. The optimally (222)‐oriented Cs2Ag0.10Na0.90ErCl6 microcrystals emit Er3+ 1540 nm light with unprecedented high quantum efficiencies of 90 ± 6% under 379 nm UV excitation (ultralarge Stokes shift >1000 nm), and a record near‐unity quantum yield of 98.6% is also obtained for (222)‐based Cs2NaYb0.40Er0.60Cl6 microcrystallites under 980 nm excitation. With combined experimental and theoretical studies, the underlying mechanism of facet‐dependent Er3+ 1540 nm emissions is revealed, which can contribute to surface asymmetry‐induced breakdown of parity‐forbidden transition and suppression of undesired non‐radiative processes. Further, the role of surface quenching is reexamined by molecular dynamics based on two facets, highlighting the drastic two‐phonon coupling effect of a hydroxyl group to 4I13/2 level of Er3+. Surface‐functionalized facets will provide new insights for tunable luminescence in double perovskites, and open up a new avenue for developing highly efficient NIR‐II emitters toward broad applications. [ABSTRACT FROM AUTHOR]

The color of micro‐structured glass can be tuned by adjusting the cross‐relaxation between Er3+ ions through the mechanism of up‐conversion, although the range of color change is very limited. Here, we report the simple and reproducible synthesis of transparent oxy‐fluoride glass‐ceramics co‐doped with Yb3+/Er3+ by melting and secondary heat treatment. By adjusting the doping content of Er3+ ions from 0.2 to 10 mol%, followed by the secondary heat treatment, the intensity of up‐conversion luminescence under 980 nm laser excitation was increased by more than 100 times, and the glass‐ceramics showed an Er3+ doping content‐depended color change of the up‐conversion luminescence from green light to red light. The elemental analysis with TEM–EDS mapping and the measurement of the lifetime of up‐conversion luminescence suggest that changes in the cross‐relaxation between Er3+ ions is the principal mechanism behind the color change of up‐conversion luminescence. As a result, the red emission due to the electronic transition of 4F9/2 is much greater than that of the green emission (4S3/2). Therefore, we present a simple and reproducible strategy to achieve an efficient up‐conversion luminescence from glass‐ceramics with a broad range of color tunability and high color purity. [ABSTRACT FROM AUTHOR]

The demand for accurate temperature readings in harsh high-temperature environments includes miniaturization, flexibility, visualization, and integrability of temperature sensors with the growing need for human development. Rare earth-doped non-contact fluorescence intensity ratio (FIR) temperature sensors have received widespread attention due to their high detection accuracy and fast response ability. However, the limitations of thermal quenching (TQ) and thermal coupling energy level differences restrict their applications. In this work, a novel temperature sensing method in Eu3+/Tb3+-doped Y2Mo3O12 negative thermal expansion (NTE) materials is proposed, which depends on different energy transfer characteristics of Eu3+- and Tb3+-doped NTE materials. Under a 295 nm excitation laser, the Y2Mo3O12:Eu3+ phosphor achieved 600% enhancement due to the charge-transfer band (CTB) absorption between O2− and MoO42−. At 573 K, the luminescence intensity of Y2Mo3O12:Tb3+ is reduced by 30 times due to the absence of energy transfer between the Tb3+ ions and Y2Mo3O12 NTE materials. The Y2Mo3O12:Eu3+/Tb3+ mixing materials enhance the relative luminescence intensity and solve the thermal coupling energy level differences, achieving high sensitivity and resolution (maximum Sr = 2.56% K−1 at 453 K). The Y2Mo3O12:Eu3+/Tb3+ flexible thin film achieves multiple naked-eye color spans, breaking free from the limitations of optical detection instruments and demonstrating strong potential for robust and direct temperature reading without equipment. This demonstrates their superior advantages for visualizing real-time high-temperature sensing with nonplanar surfaces, thermal defect diagnosis systems, intelligent battery monitoring systems, and other high-temperature sensing fields. [ABSTRACT FROM AUTHOR]

Scintillators with high spatial‐resolution and high‐stability are highly desirable for X‐ray imaging applications at unpredictable environments. To challenge state‐of‐the‐art technology, it is necessary to design high thermal stable scintillators with high‐resolution and high light yield. In this work, the zero‐thermal‐quenching Lu3Al5O12:Ce3+ (LuAG: Ce3+) transparent ceramics (TCs) is synthesized with high optical transparency. The thermoluminescence (TL) curves of the as‐obtained TCs demonstrate that the formation of the oxygen vacancies, acting as the trapping centers, can capture the carriers and then contribute to the enhancement of its thermals stability via the thermal compensation effect. The exceptional thermal‐stability of the TCs scintillator endows the monitoring of the dynamic changes of the internal structure of the objective samples without any ghosting effects during heating. In addition, given the ultra‐high uniform, transparency, and fast light decay of the TCs scintillator, the excellent spatial resolution (≈112 lp mm−1) of the X‐ray microscopic imaging is realized. These results undeniably demonstrate that the as‐obtained LuAG: Ce3+ TCs have great prospects for advancement in X‐ray detectors. [ABSTRACT FROM AUTHOR]

Owing to the large storage capacity, the transparent luminescent glass with photo‐induced coloration properties has attracted considerable interest in recent years. However, lots of the photochromic (PC) mechanisms for glass are related to the ionic valence transformation, and the study associated with the defects‐induced photochromism of glass is limited. Herein, a kind of Sm3+ doped PC cadmium glass is fabricated, for which the PC mechanism is systematically investigated by various techniques, such as XPS spectra, thermoluminescence spectra, EPR spectra, etc. The results show that the mechanism of coloration for such glass should be due to the presence of oxygen vacancy‐related electron centers. Under 365 nm light irradiation, the color of the glass turns from colorless to brown, exhibiting a large color contrast, of 62%. Utilizing the re‐absorption process between absorption spectra and emission/excitation spectra, the emission intensity of Sm3+ is reversibly regulated, indicating their promising applications as an optical storage medium. [ABSTRACT FROM AUTHOR]

Inorganic chiral materials have attracted increasing attention due to their application prospects. In this work, we synthesized the chiral nanostructured bismuth oxychloride co‐doped with Er3+/Yb3+ phosphor (D‐BYEP) by hydrothermal growth with a subsequent air‐annealing strategy using chiral sugar alcohols as the chiral inducer. The D‐BYEP emitted bright red light under the excitation of 980 nm near‐infrared laser. The temperature sensing behavior was evaluated by employing the thermally coupled (TCLs) or non‐thermally coupled (NTCLs) levels of Er3+. The maximum relative sensitivities (SR) obtained are 0.84% K−1 and 1.30% K−1 (298 K), respectively. The results show that the D‐BYEP may be ideal candidates for optical temperature sensors. We anticipate that this new type of inorganic chiral phosphor may have a range of applications in temperature measurement of light sources. [ABSTRACT FROM AUTHOR]