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In this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid‐state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from 3P1 → 1S0 transition of Bi3+ ions and characteristic emission peaks from 4f–4f transition of Eu3+ ions. Outstanding temperature‐sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (Sr) can attain 1.51% K−1 (λex = 290 nm). With temperature raising (303–513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (λex = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high‐temperature safety marker. [ABSTRACT FROM AUTHOR]

Lanthanide doped fluoride nanoparticles (NPs) possess superior X‐ray excited optical luminescence (XEOL) and persistent luminescence (XEPL), which attracts great attention in many fields. Manipulating profiles of XEOL and XEPL spectra is of siginificance for new emerging applications, however, the intrinsic sharp 4f–4f transitions of trivalent lanthanide ions only generate narrow emission profiles. Here, a convenient and versatile strategy is demonstrated to greatly modulate the emission spectrum in a broad wavelength range by constructing a new class of metal–organic framework (MOF)@NPs composites which involves electrostatic binding of positively charged various rare‐earth containing fluoride nanoparticles with the same negatively charged surface of a MOF. The emission profile can be facile designed through controlling the attached NPs composition and their relative contents on the MOF crystals. For the first time, the MOF@NPs composites are employed to realize full XEOL spectrum for multiple organic molecules sensing using the matching of their absorption profiles with the XEOL of a specific NP to effect energy transfer. In addition, time and temperature dependent multicolor XEPL evolution provides advanced information encryption. These findings can promote the exploration of a new type of nanoscintillators with innovative XEOL and XEPL performances. [ABSTRACT FROM AUTHOR]

Here, Bi3+, Er3+ co‐activated gadolinium phosphors with multimode emission properties are prepared, which can emits blue, green, and orange light under the excitation of ultraviolet, 980 and 1550 nm, respectively. Moreover, BaGd2O4:Bi3+, Er3+ can show multicolor luminescence under different excitation conditions, such as pump light source, ambient temperature, working current, and other factors. Based on the dynamic luminescence characteristics, the dynamic anti‐counterfeiting experiments are designed based on the phosphor. At the same time, the material also shows multimode temperature sensing characteristics. Under the excitation of 980 nm laser, three strong up‐conversion signals Er3+ ions are generated at 528 nm (2H11/2), 555 nm (4S3/2), and 668 nm (4F9/2), which have different temperature dependences. Based on the fluorescence intensity ratio between thermal‐coupled energy levels (2H11/2/4S3/2) and nonthermal‐coupled energy levels (2H11/2/4F9/2) of Er3+ ions, respectively, the dual‐mode temperature thermometer was constructed with high‐temperature sensitivity. In addition, the fluorescence lifetime of Bi3+ ions also has a strong temperature dependence, which can be used as another temperature detection signal, greatly improving the stability of thermometers under harsh conditions. Therefore, the material has a bright prospect in the field of anti‐counterfeiting and temperature sensing. [ABSTRACT FROM AUTHOR]

The increasing demand for radiation detection in many applications has led to demanding requirements for scintillators. Realizing low‐dose, pollution‐free, and reliable X‐ray detection has become a key technical challenge. Here, a triplet‐enhanced lanthanide radioluminescence (RL) material Ga3+/Tb3+ metallacrowns (Tb‐1) is reported. This Tb‐1 crystal emits bright green luminescence under ultraviolet light or X‐ray excitation, and the emission intensity is 286 and 242 times that of Tb3+ in inorganic salt, respectively. Tb‐1 crystal is further passivated by trioctylphosphine oxide (TOPO), and the enhanced RL intensity is equivalent to that of commercial Tl‐doped cesium iodide scintillator. In addition, RL of Tb‐1–TOPO has an extremely narrow full width at half maximum and an excellent linear response to the X‐ray dose rate. The detection limit is calculated to be 0.146 μGy s−1, which is 38 times lower than typical medical imaging doses. Triplet‐enhanced lanthanide RL provides new ideas for replacing scintillators that require high temperature synthesis processes such as inorganic phosphors and ceramics, and provides a new alternative scintillator material for flexible X‐ray monitoring, bioimaging, radiotherapy, and other applications. [ABSTRACT FROM AUTHOR]

After coating 20 Yb/2 Er:NaGdF4 core nanocrystals with a NaYbF4 shell, upconversion emission of the rare earth ions weakens. So far, the exact reason for this phenomenon is still unclear due to lack of the direct evidence. In this report, a core@shell@shell sandwich-like structure is designed and fabricated to investigate this phenomenon. We find that high Yb3+ concentration in the shell has mainly two adverse impacts: it promotes not only the deleterious back energy transfer from Er3+ in the core to Yb3+ in the shell but also the energy transfer from Yb3+ in the core to Yb3+ in the shell. To obtain nanocrystals with high upconversion efficency, appropriate Yb3+ concentration should be introduced into the shell or the transition layer. [ABSTRACT FROM AUTHOR]

Upon introducing Ca2+ dopants into the grain lattices by substituting Gd3+ ions, irregular Yb/Er:NaGdF4 nanocrystals prepared through a simple solvothermal route convert into highly uniform nanorods. Meanwhile, their upconversion luminescence intensifies by about 200 times, probably due to a modification of the crystal structure of NaGdF4 and an improvement in the crystallinity of the nanophase. [ABSTRACT FROM AUTHOR]

Lanthanoid-doped Na3Zr(Hf)F7 nanocrystals are prepared solvothermally from EtOH solutions containing MOCl2 (M: Zr, Hf), Ln(NO3)3 (Ln: La-Lu), NH4F, sodium oleate, oleic acid, oleylamine, and H2O (autoclave, 130 °C, 12 h). [ABSTRACT FROM AUTHOR]