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In this paper, we have designed long afterglow luminescent MgGeO 3 :Mn 2+ ,Yb 3+ ,Li + (MGO) nanoparticles in the first (NIR-I) and second (NIR-II) biological windows. Yb 3+ ions served not only as the trap center to enhance the NIR-I long afterglow emission of Mn 2+ at 680 nm, but also as an emitting center to produce a NIR-II long afterglow emission at ∼1000 nm. Furthermore, we have found the addition of Li + can greatly increase the NIR-II afterglow emission of Yb 3+ and the optimal amount of Mn 2+ , Yb 3+ and Li + was found to be 0.1, 0.5 and 0.5 mol%, respectively. The MGO nanoparticles synthesized using sol-gel methods showed a uniform morphology with a diameter of 50-100 nm, which were suitable for applications in bioimaging. More importantly, we have found MGO nanoparticles can be effectively excited to produce long persistent NIR-I and II luminescence using soft X-rays, suggesting that low dosage soft X-rays can also serve as a more powerful and deep tissue excitation source to recharge MGO nanoparticles. Furthermore, the MGO nanoparticles can also be re-excited to produce photo-stimulated emission under the irradiation of 650 and 808 nm NIR lasers. The in vivo imaging results have shown that MGO nanoparticles modified with folic acid (FA) can effectively realize super long-term targeted in vivo imaging of inflammation with a high sensitivity via recharging using soft X-rays and NIR lasers, which can provide not only an accurate diagnosis of inflammation, but also long-term monitoring of possible changes in the focus of inflammation in real time.

Persistent luminescence nanoparticles (PLNPs) with rechargeable near-infrared afterglow properties attract much attention for tumor diagnosis in living animals since they can avoid tissue autofluorescence and greatly improve the signal-to-background ratio. Using UV, visible light, or X-ray as excitation sources to power up persistent luminescence (PL) faces the challenges such as limited tissue penetration, inefficient charging capability, or tissue damage caused by irradiation. Here, it is proved that radiopharmaceuticals can efficiently excite ZnGa 2 O 4 :Cr 3+ nanoparticles (ZGCs) for both fluorescence and afterglow luminescence via Cerenkov resonance energy transfer as well as ionizing radiation. 18 F-FDG, a clinically approved tumor-imaging radiopharmaceutical with a short decay half-life around 110 min, is successfully used as the internal light source to in vivo excite intravenously injected ZGCs for tumor luminescence imaging over 3 h. The luminescence with similar decay time can be re-obtained for multiple times upon injection of 18 F-FDG at any time needed with no health concern. It is believed this strategy can not only provide tumor luminescence imaging with high sensitivity, high contrast, and long decay time at desired time, but also guarantee the patients much less radiation exposure, greatly benefiting image-guided surgery in the future., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The premise that long afterglow can be applied is its duration, and the persistent duration is closely related to the depth of the traps. Therefore, the stable deep traps are the key to obtain long persistent luminescence. Based on this, a strategy that X-ray excites high-gap phosphors to achieve long persistent luminescence is firstly proposed. Herein, rare earth (RE) ions doped YPO 4 phosphor is adopted as the research object as RE ions can form stable and deeper defect centers or luminescent centers in high bandgap materials. Furthermore, the efficient method of enhancing persistent luminescence is designed so that introducing Tb 3+ ions into YPO 4 :Sm 3+ crystals forms tightly bound excitons, which modulates the depth of defect centers (Sm 3+ ions), improving the afterglow behavior from Sm 3+ ions for more than two days, which is approximately 14 times stronger than the afterglow of YPO 4 :Sm 3+ phosphors itself. Finally, highly efficient in vivo deep tissue bioimaging was successfully achieved through mouse tail intravenous injection. The results indicate that the YPO 4 :Sm 3+ ,Tb 3+ phosphor possesses great promise in the field of in vivo imaging.

Persistent luminous nanoparticles (PLNPs) have been capturing increasing attention in biomedical imaging because of their long-life emission and concomitant benefits ( e.g., zero-autofluorescence background, high signal-to-noise ratio). Although there are quite some synthetic methodologies to synthesize PLNPs, those for constructing functional structured PLNPs remain largely unexplored. Herein we report the design principle, synthesis route, and proof-of-concept applications of hollow structured PLNPs with near-infrared (NIR) persistent luminescence, namely afterglow, and tunable sizes for tumor afterglow imaging and chemical/photodynamic therapies. The design principle leverages on the crystallization of the immobilized parent ions on the purgeable carbon spheres. This strategy provides large and size-tunable hollow cavities to PLNPs after calcination. Building on the hollow cavity of PLNPs, high chemical drug (DOX) or photosensitizer (Si-Pc) loading can be achieved. The DOX/Si-Pc-loaded hollow PLNPs exhibit efficient tumor suppression based on the features of large cavity and afterglow of PLNPs. These hollow structured PLNPs, like traditional solid PLNPs, are quite stable and can be repeatedly activated, and particularly can selectively target tumor lesion, permitting rechargeable afterglow imaging in living mice. Our research supplies a strategy to synthesize hollow structured PLNPs, and hopefully it could inspire other innovative structures for cancer theranostics.

Near infrared (NIR)-emitting persistent luminescent nanoparticles (NPLNPs) have attracted much attention in bioimaging because they can provide long-term in vivo imaging with a high signal-to-noise ratio (SNR). However, conventional NPLNPs with large particle sizes that lack modifiable surface groups suffer from many serious limitations in bioimaging. Herein, we report a one-step synthesis of amino-functionalized ZnGa2O4:Cr,Eu nanoparticles (ZGO) that have an ultrasmall size, where ethylenediamine served as the reactant to fabricate the ZGO as well as the surfactant ligand to control the nanocrystal size and form surface amino groups. The ZGO exhibited a narrow particle size distribution, a bright NIR emission and a long afterglow luminescence. In addition, due to the excellent conjugation ability of the surface amino groups, the ZGO can be easily conjugated with many bio-functional molecules, which has been successfully utilized to realize in vitro and in vivo imaging. More importantly, the ZGO achieved re-excitation imaging using 650 nm and 808 nm NIR light in situ, which is advantageous for long-term and higher SNR bioimaging.

In this paper, near infrared-emitting long-persistence luminescent porous Zn1.1Ga1.8Ge0.1O4:Cr(3+), Eu(3+) @SiO2 nanoprobes have been prepared using mesoporous silica nanospheres both as morphology-controlling templates and as vessels. These nanoprobes possessed an excellent capacity for drug delivery and allowed for real-time monitoring of the delivery routes of the drug carriers in vivo. The nanoprobes demonstrated a typical mesoporous structure, a brighter NIR emission (696 nm) and a long afterglow luminescence that persisted for 15 d. Furthermore, after surface modification with folic acid (FA), a tumor-targeting group, these nanoprobes exhibited an excellent ability to target tumors with high sensitivity in vitro and in vivo. Importantly, these modified nanoprobes could accurately diagnose tumors and allow for long-term tumor monitoring via in situ and in vivo re-excitation by a red LED lamp. Furthermore, the drug release data demonstrated that the modified nanoprobes could be loaded with a large amount of doxorubicin hydrochloride (DOX) and showed sustained release behavior. Together, the results of this study indicate that these nanoprobes can accurately diagnose tumors, allow for long-term in vivo and in situ monitoring and release DOX in situ to cure tumors., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this paper, X‐ray–induced multicolor long afterglow and photostimulated luminescence from Sr3(PO4)2: Pr3+ was reported. The Rietveld refinement results have confirmed the as‐prepared sample was pure Sr3(PO4)2 phase with hexagonal crystal system. And Sr3(PO4)2: Pr3+ showed an excellent X‐ray–induced long afterglow luminescent performance. Under the excitation of X‐ray, the sample showed multicolor long afterglow luminescence from UVC to red region located at 268, 359, 466, 548, 604.3 and 685 nm, which can be ascribed to 4f5d‐3H4, 4f5d‐ 1D2, 4f5d‐3P0, 3P0→3H5 and 1D2→3H4, respectively. And the strongest afterglow emission intensity appeared at 468 nm. Furthermore, only 30 s X‐ray irradiation can induce 12 h afterglow emission, which afterglow emission intensity of 468 nm still reached 3.71 × 104 cps and was about 37.1 times stronger than the background intensity. In particular, the relation between 268 nm afterglow emission intensity and 468 nm afterglow emission intensity showed good linearity. And the UVC afterglow emission can be easily "observed" via the visible afterglow light. Furthermore, Sr3(PO4)2: Pr3+ possessed an excellent photostimulated luminescence (PSL) under the excitation of 980 nm NIR laser and the PSL intensity of the 12 circle still arrived at 1.26 × 105 cps, which was about 37.1 times stronger than the afterglow emission intensity after 5 h decay. All these results showed that the as‐prepared Sr3(PO4)2: Pr3+ phosphor was an excellent X‐ray–induced long afterglow luminescence phosphor, which possessed large potential applications in the medical field. [ABSTRACT FROM AUTHOR]

In this paper, X‐ray‐activated super long persistent ultraviolet A luminescence from Ca3(PO4)2: Ce3+ has been observed. The crystal structure analysis has shown that the as‐prepared samples are pure β‐Ca3(PO4)2 phases with rhombohedral structure and R3c space group. The photoluminescent spectra of the samples all consist of a broad band in 340–400 nm UVA1 region, which is assigned to the 5d1–4f1 electronic transition of Ce3+ ions. More important, under the 3 min X‐ray irradiation, Ca3(PO4)2: Ce3+ show super long persistent luminescence in the UVA1 region, which can persist for more than 16 h. And its afterglow intensity after 16 h decay is still 4.10 times stronger of the back ground intensity. Furthermore, only 10 s X‐ray irradiation can induce excellent long persistent UVA luminescence of Ca3(PO4)2: 0.08Ce3+, which can persist for more than 5 h and afterglow emission intensity is about 3.03 times of the background intensity. The trap analysis has confirmed that the different X‐ray irradiation time do not create new traps and there is the same trap with 0.75 eV trap depth existing even under the extremely low X‐ray dose (10 s X‐ray irradiation). Furthermore, under 10 s X‐ray irradiation, the thermoluminescence (TL) intensity of Ca3(PO4)2: 0.08Ce3+ still reaches 0.32 times of the initial TL intensity even after 120 min, which thus leads to the super long persistent luminescence. Thus, the large amounts of trapped electrons induced by the high energy X‐ray irradiation are the principal cause for super long persistent UVA luminescence of Ca3(PO4)2: Ce3+. [ABSTRACT FROM AUTHOR]

Mixed-valence Eu2+/3+-activated phosphors have attracted wide attention due to their excellent luminescence tunability. Steady control of the Eu2+/Eu3+ ratio is the key to achieving reproducible Eu2+/3+ co-doped materials. In this work, BaMgP2O7:xEu2+/3+ (BMPO:Eu, x = 0.001–0.20) was successfully prepared by the traditional solid-state method in air. Eu3+ undergoes selective self-reduction at Ba2+ sites surrounded by a [P2O7] framework, leading to quantitive Eu2+/Eu3+. The phosphors exhibit a blue-violet emission band at ∼410 nm due to 5d–4f transitions of Eu2+ and a group of red emission peaks from 5D0–7FJ of Eu3+. Controllable multicolor emissions are realized by regulating the Eu content and excitations. A linear response of overall luminescence intensity to irradiation dose makes the phosphor appropriate for X-ray detection. The combination of UV-blue excitation-dependent color evolution and X-ray luminescence qualifies the phosphors with great potential for multi-level anti-counterfeiting. In addition, Eu3+ presents abnormal anti-thermal quenching, so that the fluorescence intensity ratio (FIR) of Eu2+/Eu3+ changes in the temperature range of 300–520 K, suggesting a promising application in optical thermometry. Therefore, selectively partial self-reduction in a multi-cationic host is an effective strategy to design mixed-valence co-doped materials, providing a multiplicity of applications. [ABSTRACT FROM AUTHOR]

We report a novel bright orange persistent luminescence (PersL) phosphor BaZnGeO4:Bi3+ with broad emission and PersL spectra. Its crystal structure, photoluminescence (PL) spectra, thermoluminescence (TL) spectra and PersL spectra were investigated in detail. The two emission bands at 440 nm and 595 nm originate from Bi3+ ions in normal Ba2+ sites (Bi1) and Ba2+ sites close to vacancy defects (Bi2), respectively. The introduction of VZn′′ and VGe′′′′ defects improves the emission intensity of Bi2 more than that of Bi1, demonstrating that Bi2 is related to the vacancy defects. The orange emission and PersL properties of BZGO:Bi3+ can be improved when a little VZn′′ and VGe′′′′ defects are introduced, because the introduction of VZn′′ and VGe′′′′ defects makes it easier for Bi3+ to enter in Ba2+ sites; and for PersL, VZn′′ and VGe′′′′ defects can perform as the effective trap centers to capture more charges, which is beneficial for PersL. BZGO:Bi3+ has quite good thermal stability, and the bright orange PersL can be observed by the naked eye for 1 h. Finally, a feasible PersL mechanism of BZGO:Bi3+ was proposed to clarify the PersL‐generation process. [ABSTRACT FROM AUTHOR]

The development of nanotechnology has drawn increased attention to the risks of nanoparticles (NPs). In this work, the near-infrared persistent luminescence imaging technique was used to track the biodistribution of NPs in vivo in zebrafish. Zebrafish were used as a vertebrate animal model to show NPs distribution and the effects of exposure. ZnGa2O4:Cr (ZGOC) was chosen as the probe in this work. In continuous exposure experiments, the results showed more particles accumulated in the intestines than in the gills in both groups. In both the gills and abdomen, the NPs contents were greater in the ZGOC–NH2-treated groups than in the ZGOC groups, and the NPs caused damage to the gills and intestines. Removal exposure experiments indicated that ZGOC and ZGOC–NH2 could be excreted from the body. The metabolism, excretion of NPs, the quantification and monitoring of NPs behavior in biological systems should be examined in further studies. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) persistent phosphor ZnGa2O4:Cr3+ (ZGC) has unique deep‐tissue rechargeable afterglow properties. However, the current synthesis leads to agglomerated products with irregular morphologies and wide size distributions. Herein, we report on in vivo rechargeable mesoporous SiO2/ZnGa2O4:Cr3+ (mZGC) afterglow NIR‐emitting nanocomposites that are made by a simple, one‐step mesoporous template method. At less than 600 °C, pores in mesoporous silica nanoparticles (MSNs) act as nanoreactors to generate in situ ZnGa2O4:Cr3+ NIR‐persistent phosphors. The as‐synthesized mZGC preserves defined size, morphology, and mesoporous nanostructure of the MSNs. The persistent luminescence of the as‐synthesized mZGC is recharged in a simulated deep‐tissue environment (e.g., ≈8 mm pork slab) in vitro by using red light (620 nm). Moreover, mZGC can be repeatedly activated in vivo for persistent luminescence imaging in a live mouse model by using white LED as a light source. Our concept of utilizing mesoporous silica as nanoreactor to fabricate ZGC PL nanoparticles with controllable morphology and preserved porous nanostructure paves a new way to the development and the wide application of deep tissue rechargeable ZGC in photonics and biophotonics. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we utilized double layer method to prepare SrAl2O4:Eu (SAOE) film on silicon substrate (400). The Al2O3 layer (about 200nm) was used as a hetero-buffer layer to eliminate the large difference of crystal lattice and thermal mismatch between the SAOE and silicon substrate. Thin SAOE layer (about 600nm) was grown on Al2O3 layer as homo-buffer layer to reduce internal stress during film growth process. On double buffer layers, continuous sputtering formed about 1.5μm SAOE film. The resulting thick SAOE/Al2O3/Si film possessed both excellent photoluminescence (PL) and mechanoluminescence (ML) properties. The similarity of PL and ML spectra suggested that PL and ML both originated from same emitting center of Eu2+. The strong ML intensity showed that the as-prepared SAOE film can be regarded as an indicator to detect stress distribution of an object. The thermoluminescent (ThL) results indicated that a large amount of trapped electrons existing in the resulting film answered for the strong ML intensity. [Copyright &y& Elsevier]

A three-dimensional sheet-like micromaterial Eu0.15La0.85 (TTA)3phen has been synthesized by the oil-water interfacial self-crystal growth method at room temperature without the assistance of any surfactant, catalyst, or template. The resulting micromaterial consists of uniform microsheets with a length of 500–800 nm, width of 300–400 nm, and thickness of ∼80 nm. The appropriate overlap between absorption of ligand TTA and excitation of the microsheets indicated that TTA can efficiently transfer the absorbed energy to Eu3+. Furthermore, the maximum intensity peak was located at 613 nm, which shows the microsheets show pure red emission. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, Ca2MgSi2O7:Eu,Dy (CMSED) microparticles were used as sensors to detect the stress distribution of aluminium base. The results show that the dependence of mechanoluminescence (ML) intensity on square of strain gauge shows excellent linearity, which is consistent with the relation between strain energy and square of strain gauge. This indicates that strain energy is responsible for the origin of ML. Furthermore, the stress distribution of aluminium base with a hole has been visualized using CMSED film, which is identical to previously calculated stress distribution. All the results show that CMSED microparticles can be regarded as sensors to detect the stress distribution of object. [ABSTRACT FROM AUTHOR]

Abstract: From the viewpoint of utilizing a mechanoluminescent (ML) material as a light source, the surface of the ML material should have the most effective photoreaction with the strongest photointensity from the ML material. A hybrid material that combines an ML material and a photoreactant material is a promising way of accomplishing this. This paper discusses a preparation method for a hybrid material consisting of the ML material and TiO2 photocatalytic nanoparticles. By using the surface sol–gel method, we succeeded in immobilizing the TiO2 photocatalytic nanoparticles on the surface of the ML material, thus preparing a hybrid material where the nanoparticles took over the original mechanoluminescence and photocatalysis activities. [Copyright &y& Elsevier]

Abstract: This paper reports the photoluminescence (PL) properties of nanocrystalline CaZrO3:Tm phosphor synthesized by the polymerizable complex method based on the Pechini-type reaction. Nanosized phosphors with paving stone morphology were prepared at a relatively low temperature about 800°C with the particle size being about 30nm. The transmission electron microscope (TEM) images showed that further heat treatment at higher temperature could increase the particle size to 50nm, but its morphology remained unchanged. The luminescence spectra indicated that the blue emission of CaZrO3:Tm could be produced by four kinds of excitation energies, i.e. the charge transfer (CTS) between Tm3+-O2−, band–band absorption of host, the absorption defects in the host and the 3H6–1D2 transition. The luminescent mechanism of CaZrO3:Tm was deduced tentatively based on the luminescence spectra. [Copyright &y& Elsevier]

Abstract: Nanocrystalline europium-doped AZrO3 (A=Ca, Sr, Ba) were prepared by Pechini-type complex sol–gel method. The attained results of XRD and SEM suggest that this synthesis method appears to be an efficient method to prepare the luminescence materials AZrO3:Eu with high homogeneity and purity. At the same time, the photoluminescence results indicate that Eu3+ ions in monoclinic CaZrO3 have the worst symmetry among these phosphors. Furthermore, CaZrO3:Eu exhibit the strongest luminescent intensity and pure red color which show that this phosphors may be more possible to be regarded as a promising candidate for applications in displays. [Copyright &y& Elsevier]

Abstract: In this paper nanosized luminescent materials YVO4:Sm and YVO4:Dy were synthesized by complex-based sol–gel method. A certain amount of soluble starch participates in this synthesis as a chelate agent. Homogeneous and fine powders have been successfully prepared because soluble starch consists of long-chain glucose units which cannot only provide chelating units but also hinder the growth of nanoparticles. The experimental results have proved that the host YVO4 can effectively transfer the absorbed energy to the activators Sm3+ and Dy3+. Under the excitation of the host absorption, phosphors can emit yellow light for YVO4:Dy3+ nanoparticles and orange light for YVO4:Sm3+ nanoparticles, respectively. [Copyright &y& Elsevier]

Abstract: In this paper, thulium doped ZrO2 nanocrystals with different phases were prepared by Pechini sol–gel complex method. The effects of host structure, phases and concentration on luminescence properties of Tm3+ ions were investigated. With the increase of the concentration of Tm3+ ions, the phosphors phase transformed from monoclinic to tetragonal structure and all the phosphors emitted blue light. However, because the environment symmetry around Tm3+ in m-ZrO2 (C2h) is worse than that of t-ZrO2 (D4h), there were still obvious differences in the emission and excitation. The reason was investigated with the help of energy level diagram. In addition, the quenching concentration of Tm3+ in ZrO2 host is 1 m/m%. [Copyright &y& Elsevier]

Abstract: This paper reports the luminescence effects of Tm3+ doped YVO4:Dy nanocrystalline synthesized by a modified Pechini method. The structure and morphology were characterized by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The relationship between the ratio of Tm3+/Dy3+ and the chromaticity is studied, i.e. Tm3+ ion doping effectively tunes the emission color of YVO4:Tm x Dy1−x phosphors. The best white light emission was observed with YVO4:1%(Tm0.6Dy0.4). These results indicate that thulium doped YVO4:Dy phosphors are promising white-emitting luminescence materials. [Copyright &y& Elsevier]

Abstract: The influence of lithium doping on the crystallization behavior, morphology, and enhancement in photoluminescence intensity of SnO2:Eu was investigated. In order to attain high homogeneous and pure samples, the Pechini type sol–gel method was adopted for the synthesis at low temperature (500°C). The structure and morphology were characterized by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The results indicate that the Li+ doping could accelerate the crystallization of SnO2 and the particle size of the phosphors is below 100nm. In particularly, the incorporation of Li+ ions into SnO2 lattice could induce a remarkable increase of photoluminescence intensity. [Copyright &y& Elsevier]

Abstract: Nanocrystalline ZrO2:Eu was synthesized by complexing sol–gel method. The effects of heat treatment on structure, grain size and luminescence properties of ZrO2:Eu were studied with X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence measurements. The dependence between the fluorescence emission and the crystalline structure is discussed. [Copyright &y& Elsevier]

Abstract: Nanocrystalline europium-doped tine oxide (SnO2:Eu) were synthesized by a polyacrylamide gel method. The effects of heat treatment on structure, grain size and luminescence properties of SnO2:Eu were studied with X-ray powder diffraction, transmission electron microscopy and photoluminescence measurements. The results indicate that high heat treatments can enhance greatly luminescence intensity of the samples. Furthermore, the presence of carbon network/cages in the polyacrylamide gel can effectively prevent particles agglomeration, so even when sintered at higher temperatures (1000°C), the grain size is still below 20nm. [Copyright &y& Elsevier]

This paper reports the photoluminescence (PL) properties of nanocrystalline YVO4: Tm phosphor synthesized by the polymerizable complex method based on the Pechini-type reaction. The powder was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectroscopy and PL. The results of XRD and TEM show that, high-quality nanopowders with controlled morphology and microstructure were prepared at a relatively low temperature about 700°C. Upon ultra violet excitation the vanadate host transferred energy to thulium ions efficiently and strong blue emission (475nm) assigned to 1G4→3H6 transmission is observed. By analyzing excitation and emission spectra of thulium doped yttrium vanadate, we deduced the mechanism of the energy transfer between vanadate host and thulium ions. [Copyright &y& Elsevier]

Nanocrystalline europium doped yttrium orthovanadate (YVO4:Eu) were synthesized by the polyacrylamide gel method. For a comparative evaluation, bulk YVO4:Eu was prepared by solid-state reaction. On the basis of X-ray powder diffraction, scanning and transmission electron microscopy and luminescence measurements, the polyacrylamide gel method appears to be a more efficient method to prepare the luminescence materials YVO4:Eu with high homogeneity, purity and luminescence intensity. [Copyright &y& Elsevier]

In this paper, X‐ray–induced multicolor long afterglow and photostimulated luminescence from Sr3(PO4)2: Pr3+ was reported. The Rietveld refinement results have confirmed the as‐prepared sample was pure Sr3(PO4)2 phase with hexagonal crystal system. And Sr3(PO4)2: Pr3+ showed an excellent X‐ray–induced long afterglow luminescent performance. Under the excitation of X‐ray, the sample showed multicolor long afterglow luminescence from UVC to red region located at 268, 359, 466, 548, 604.3 and 685 nm, which can be ascribed to 4f5d‐3H4, 4f5d‐ 1D2, 4f5d‐3P0, 3P0→3H5 and 1D2→3H4, respectively. And the strongest afterglow emission intensity appeared at 468 nm. Furthermore, only 30 s X‐ray irradiation can induce 12 h afterglow emission, which afterglow emission intensity of 468 nm still reached 3.71 × 104 cps and was about 37.1 times stronger than the background intensity. In particular, the relation between 268 nm afterglow emission intensity and 468 nm afterglow emission intensity showed good linearity. And the UVC afterglow emission can be easily "observed" via the visible afterglow light. Furthermore, Sr3(PO4)2: Pr3+ possessed an excellent photostimulated luminescence (PSL) under the excitation of 980 nm NIR laser and the PSL intensity of the 12 circle still arrived at 1.26 × 105 cps, which was about 37.1 times stronger than the afterglow emission intensity after 5 h decay. All these results showed that the as‐prepared Sr3(PO4)2: Pr3+ phosphor was an excellent X‐ray–induced long afterglow luminescence phosphor, which possessed large potential applications in the medical field. [ABSTRACT FROM AUTHOR]

Here, we have developed a novel ultra long ultraviolet-A afterglow material CaMgGeO 4 : Bi3+, which shows more than 24 h UVA afterglow emission peaked at 346 nm. The crystal structure shows that the prepared sample is a pure phase with an orthogonal system of Pmnb space group. The composition of valence band and conduction band was analyzed by the density of states, which reveals that the bandgap of the CaMgGeO 4 matrix is 3.69 eV. The photoluminescence spectrum of the sample consists of a broadband in the 320–400 nm UVA region, which belongs to the 3P 1 → 1S 0 electron transition of Bi3+. More importantly, under the excitation of ultraviolet lamp for 3 min, CaMgGeO 4 : Bi3+ exhibited an UVA ultra long persistent luminescence (LPL) with a duration of more than 24 h, which afterglow emission intensity still reaches 1500 cps and is about 6 times of the background intensity. In addition, the UVA emission of CaMgGeO 4 : Bi3+ after 13 h day can be repeatedly by short periods of low-energy light sources stimulation. The thermoluminescence analysis indicates that the presence of shallow and deep traps is responsible for excellent UVA-LPL and photo-stimulate luminescence (PSL). The excellent LPL and PSL properties can prompt CaMgGeO4: Bi3+ phosphor to be widely used in the field of photodynamic therapy. [ABSTRACT FROM AUTHOR]

Here, a novel super‐long, ultraviolet A region (UVA), persistent luminescent (PerL) material, LiYGeO4:Bi3+, is developed. After irradiation at 254 nm for 10 min, the UVA PerL of LiYGeO4:Bi3+ can persist for more than 300 h. In addition, the LiYGeO4:Bi3+ also possesses a strong UVA emission with a power density of 11.83 mW m−2 at 10 s after the removal of the excitation source. Even after 72 h, the UVA PerL emission spectrum can still be clearly detected, which is the same as the photoluminescence emission spectrum and originated from the Bi3+ emitting centers. Furthermore, LiYGeO4:Bi3+ also exhibits a photostimulated PerL property, which can be easily activated with a red light emitting diode (LED) or NIR laser irradiation after the long‐term decay. Combining the results of the PerL excitation, absorption, and thermoluminescence spectra, the excellent UVA PerL of LiYGeO4:Bi3+ can be ascribed to the existence of abundant trap sites created by the loss of Li+. This excellent PerL material can make up for deficiency of PerL materials in the UVA region and greatly expand the application of PerL materials in the biomedical, energy, environmental, and catalysis fields. [ABSTRACT FROM AUTHOR]

In this paper, X‐ray‐activated super long persistent ultraviolet A luminescence from Ca3(PO4)2: Ce3+ has been observed. The crystal structure analysis has shown that the as‐prepared samples are pure β‐Ca3(PO4)2 phases with rhombohedral structure and R3c space group. The photoluminescent spectra of the samples all consist of a broad band in 340–400 nm UVA1 region, which is assigned to the 5d1–4f1 electronic transition of Ce3+ ions. More important, under the 3 min X‐ray irradiation, Ca3(PO4)2: Ce3+ show super long persistent luminescence in the UVA1 region, which can persist for more than 16 h. And its afterglow intensity after 16 h decay is still 4.10 times stronger of the back ground intensity. Furthermore, only 10 s X‐ray irradiation can induce excellent long persistent UVA luminescence of Ca3(PO4)2: 0.08Ce3+, which can persist for more than 5 h and afterglow emission intensity is about 3.03 times of the background intensity. The trap analysis has confirmed that the different X‐ray irradiation time do not create new traps and there is the same trap with 0.75 eV trap depth existing even under the extremely low X‐ray dose (10 s X‐ray irradiation). Furthermore, under 10 s X‐ray irradiation, the thermoluminescence (TL) intensity of Ca3(PO4)2: 0.08Ce3+ still reaches 0.32 times of the initial TL intensity even after 120 min, which thus leads to the super long persistent luminescence. Thus, the large amounts of trapped electrons induced by the high energy X‐ray irradiation are the principal cause for super long persistent UVA luminescence of Ca3(PO4)2: Ce3+. [ABSTRACT FROM AUTHOR]

In this paper, a low dose X-ray induced long afterglow luminescent phosphor Sr 3 MgSi 2 O 8 :Pr3+ has been reported. The structure analysis shows the as-prepared samples possess good crystallinity and the emitting center Pr3+ is more likely to occupy the lattice position of Sr2+ due to their similar ionic radius. And under 471.1 nm excitation, Sr 3 MgSi 2 O 8 :Pr3+ shows bright visible lights peaked at 545.5, 617.1 and 648.6 nm, respectively, corresponding to the transitions of 3P 0 →3H 5 , 3P 0 →3H 6 and 3P 0 →3F 2 of Pr3+. After the X-ray irradiation, this phosphor shows strong ultraviolet C (291.7 nm), blue (493.2 nm) and red lights (617.1 nm). More important, only 5 s X-ray irradiation X-ray irradiation can easily charge Sr 3 MgSi 2 O 8 :Pr3+ to produce 5400 s afterglow emission. Even after 5400 s, its afterglow emissions still remain strong, which is about 20 times of the background intensity. The thermoluminescent results indicate that Sr 3 MgSi 2 O 8 possesses a high absorption rate for X-rays and thus X-ray irradiation can excite the host to produce large number of electrons, Secondary electron, which would rapidly fill up the traps and thus produce excellent long afterglow luminescence. In addition, the existing suitable traps with 0.76 eV trap depth are also favorable for persistent luminescence at room temperature. Thus, Sr 3 MgSi 2 O 8 :Pr3+ is confirmed to be a very efficient low dose X-ray induced long afterglow luminescent phosphor. [ABSTRACT FROM AUTHOR]

In this paper, X-ray induced color-tunable long afterglow luminescent material Ca 9-x Tb(PO 4) 7 :xMn2+ was synthesized by high-temperature solid state reaction. The effects of Mn2+ doping concentration on the properties of the samples were studied by XRD, SEM, fluorescence and afterglow spectra. The results showed that there was a very efficient energy transfer between Tb 3+ and Mn 2+ under X-ray excitation, with a transfer efficiency of up to 94.6%, which also contributed to the tunable green-red emission. With the increase of Mn2+ concentration, the green afterglow emissions of Tb3+ mainly at 546.9 nm gradually decreased and even disappeared, while the red afterglow emissions of Mn2+ at 647.3 nm gradually increases due to excellent energy transfer. When the doping concentration of Mn2+ was 0.07, the red afterglow emissions were the strongest. Furthermore, even at low-dose radiation (3 mGy), the sample still possessed excellent afterglow performance, which can persist for more than 5 h. In addition, the samples also showed excellent photostimulated luminescence properties, which can be persist for many cycles by the irradiation of 980 nm laser. The thermoluminescence results revealed that the doping Mn2+ ions can not only enhance the trap concentrations obviously but also created new deep traps with trap depth of 0.864 eV, which thus resulted in better long afterglow luminescence and photostimulated luminescence properties of Ca 9 Tb(PO 4) 7 :Mn2+. [ABSTRACT FROM AUTHOR]

Eu 3+ and Bi 3+ doped calcium molybdate particles were carefully examined by high resolution electron microscopy. Visualization of high atomic-weight dopants inside the relatively lightweight calcium molybdate matrix was enabled with the aid of an off-axis high-angle-annular-dark-field (HAADF) technique. The incorporation behaviors of Eu 3+ , Bi 3+ and Eu 3+ & Bi 3+ dopants in the CaMoO 4 host were investigated. We consistently found that, Eu 3+ ions were evenly distributed in the CaMoO 4 host (no clustering), while Bi 3+ ions preferred to take the form of nanosized clusters (∼2 nm). Interestingly, in Eu 3+ & Bi 3+ co-doped sample, a minor amount of Bi 3+ promoted the clustering of Eu 3+ ions. The clustering of Eu 3+ ions might be relevant to an energy transfer process in co-doped phosphors. [ABSTRACT FROM AUTHOR]

Abstract: The influence of Mg2+ doping on the crystallization behavior and enhancement in photoluminescence intensity of SnO2:Eu was investigated. Highly homogeneous and pure samples were prepared by Pechini type sol–gel method and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectroscopy and photoluminescence. The results indicated that the incorporation of Mg2+ ions into SnO2 lattice could induce a remarkable increase of photoluminescence and the primary reasons were deduced. [Copyright &y& Elsevier]

We report a novel bright orange persistent luminescence (PersL) phosphor BaZnGeO4:Bi3+ with broad emission and PersL spectra. Its crystal structure, photoluminescence (PL) spectra, thermoluminescence (TL) spectra and PersL spectra were investigated in detail. The two emission bands at 440 nm and 595 nm originate from Bi3+ ions in normal Ba2+ sites (Bi1) and Ba2+ sites close to vacancy defects (Bi2), respectively. The introduction of VZn′′ and VGe′′′′ defects improves the emission intensity of Bi2 more than that of Bi1, demonstrating that Bi2 is related to the vacancy defects. The orange emission and PersL properties of BZGO:Bi3+ can be improved when a little VZn′′ and VGe′′′′ defects are introduced, because the introduction of VZn′′ and VGe′′′′ defects makes it easier for Bi3+ to enter in Ba2+ sites; and for PersL, VZn′′ and VGe′′′′ defects can perform as the effective trap centers to capture more charges, which is beneficial for PersL. BZGO:Bi3+ has quite good thermal stability, and the bright orange PersL can be observed by the naked eye for 1 h. Finally, a feasible PersL mechanism of BZGO:Bi3+ was proposed to clarify the PersL‐generation process. [ABSTRACT FROM AUTHOR]

In this paper, Short-time X-ray irradiation induced long afterglow and photostimulated luminescence from Sr 2 GeO 4 : Pr3+ has been observed. Under the X-ray irradiation, Sr 2 GeO 4 : Pr3+ can produce long afterglow and photostimulated visible luminescence mainly located at 490, 547 and 629 nm, which are attributed to 3P 0 →3H 4 , 3P 0 →3H 5 and 3P 0 →3H 6 of Pr3+, respectively. More important, even 5 s X-ray irradiation which was less than the X-ray damage from one CT scan, can induce 5400 s afterglow emission. Furthermore, due to its excellent photostimulated luminescence properties, the afterglow emission intensity of Sr 2 GeO 4 : Pr3+can be significantly improved under the radiation of 980 and 808 nm lasers and the emission intensities can still be maintained even after 12 testing cycles. The thermoluminescence results show that Pr3+ doping produces three different traps. Among these, the traps with 0.64 and 0.71 eV trap depth result in excellent X-ray long afterglow luminescence of Sr 2 GeO 4 : Pr3+. While the deep trap of 0.96 eV determines the photostimulated luminescence properties. These results indicate that Sr 2 GeO 4 :Pr3+ possesses excellent long afterglow and photostimulated luminescence under the X-ray irradiation in safety range, which thus can be regarded as in vivo light source to efficiently conduct photodynamic therapy in the future. Sr 2 GeO 4 :Pr3+ long afterglow material has been prepared, which has the characteristics of Short-time irradiation by X-ray induced long afterglow and photostimulated luminescence. The result showed that the afterglow emission peaks are mainly located at 490 nm, 547 nm and 629 nm, corresponding to the 3P 0 →3H j (j = 4, 5, 6) characteristic transitions of Pr3+, respectively. When the doping concentration of Pr3+ is 0.5 %, the sample possesses the best afterglow and the afterglow emission can still be observed after 5400 s. And the X-ray excitation can produce much better afterglow performance than 254 nm excitation. In addition, the sample also showed good afterglow performance under short-time (5 s) X-ray radiation. At the same time, the sample possesses strong PSL characteristics under the excitation of 980 nm and 808 nm lasers and still maintains strong PSL afterglow intensity after 12 cycles of measurements. Furthermore, the trap density under X-ray excitation is much higher than that under UV excitation, which thus produce much longer afterglow emission under the X-ray irradiation. These results indicate that Sr 2 GeO 4 :Pr3+ possesses excellent long afterglow and photostimulated luminescence under the X-ray irradiation in safety range, which thus can be regarded as in vivo light source to efficiently conduct photodynamic therapy in the future. [Display omitted] • X-ray induced long afterglow material Sr 2 GeO 4 :Pr3+ shows excellent photostimulated luminescence properties. • Sr 2 GeO 4 :Pr3+ showed good afterglow performance under short-time (5 s) X-ray radiation. • A model is presented to clarify the afterglow mechanisms of Sr 2 GeO 4 :Pr3+. [ABSTRACT FROM AUTHOR]

Abstract lanthanide-doped phosphates luminescence materials have attracted increasing attention in biomedical applications. Among them, lanthanide-doped LuPO 4 nanophosphors have potentical for multimodal bioimaging due to good biocompatible and luminescence feasures and excellent X-ray absorption properties. However, research on the application of multimodal bioimaging using the lanthanide-doped LuPO 4 nanophosphors is still scarce. Here, dual-modal LuPO 4 :Nd3+ nanophosphors with second near infrared (NIR-II) optical imaging and X-ray computed tomography (CT) imaging are reported. LuPO 4 :Nd3+ nanoparticles (NPs) have been successfully prepared through a hydrothermal method under the chelator of critic acid. On the basis of the strong Nd3+ ion emission (at around 1064 nm), tissue penetration depths as large as 15 mm and the optical imaging in vivo have been demonstrated in the second near-infrared window, where absorption and scattering by human tissue are reduced drastically. Furthermore, the incorporation of Lu into the nanocystalline structure supplies strong X-ray absorption properties, making them promising for CT imaging as contrast agents. And, the nanophosphors exhibite relatively low toxicity and good biocompatibility for concentrations up to 800 mg L−1, suggesting their safety for in vivo imaging. All these results suggested that the LuPO 4 :Nd3+ nanoparticles can be regarded as potential candidates for dual-mode deep tissue NIR-II luminescence/CT imaging. [ABSTRACT FROM AUTHOR]

Abstract Yellow/orange-emitting Ba 2 Mg(PO 4) 2 : Eu2+ phosphors with uniform particle size distribution were successfully prepared by Pechini sol-gel method. The emission spectra of Ba 2-x Mg(PO 4) 2 : xEu2+ phosphor displayed one broad band centered at about 560 nm which can be assigned to the 4f65d1→4f7 transitions of the Eu2+. Along with the increasing of the Eu2+ doping amount the emission peak intensity increased till the Eu2+ concentration ratio is 4 mol%. In Ba 2 Mg(PO 4) 2 : Eu2+ phosphors, Eu2+ ion occupy two different lattice sites by substitution for Ba2+ ions. with the increase of the doping concentration of Eu2+ ion, the ability for Eu2+ enter into the first site of Ba 2 Mg(PO 4) 2 in the lattice is increasing. [ABSTRACT FROM AUTHOR]

We have designed a novel strategy to develop efficient X-ray-induced long afterglow luminescent materials. Eu3+ ions as electron receptors were chosen as trap creators and emitting centers and scintillator Bi 4 Ge 3 O 12 was regarded as the host to efficiently absorb X-ray. The obtained results showed that Bi 4 Ge 3 O 12 : Eu3+ can produce excellent x-ray induced red long afterglow luminescence which appeared at 589, 612, 655 and 705 nm corresponding to the 5D 0 →7F j (j = 1,2,3,4) transitions, respectively. The best afterglow performance was shown when the Eu3+ doping concentration was 0.5% at this time, and Bi 4 Ge 3 O 12 :Eu3+ also showed a strong afterglow under short-time X-ray excitation. The thermoluminescence results indicated the X-ray irradiation can produce massive secondary electrons and the abundant free electrons can easily induce Eu3+ ions to formed Eu2+* traps, which resulted in the excellent x-ray induced long afterglow luminescence of Bi 4 Ge 3 O 12 : Eu3+. Furthermore, the X-ray induced long afterglow red luminescence from Bi 4 Ge 3 O 12 :Eu3+ can persist for more than 5400 s, which still can be clearly observed by naked eyes even after 5400 s. All these results our designed strategy can realize the development of good X-ray induced long afterglow luminescent materials from scintillator to phosphor. • X-ray excited long afterglow material Bi 4 Ge 3 O 12 :Eu3+ shows red afterglow. • The transformation from scintillator to long afterglow material. • The Eu3+ to Eu2+ transition is responsible for the afterglow of Bi 4 Ge 3 O 12 :Eu3+. • A model is presented to clarify the afterglow mechanisms of Bi 4 Ge 3 O 12 :Eu3+. [ABSTRACT FROM AUTHOR]

Here, a kind of porous nanoparticles GdAlO 3 :Cr 3+ , Sm 3+ (GAO:Cr,Sm) which own magnetic resonance and long persistent luminescent properties have been synthesized. The spherical morphology and narrow size distribution would allow the GAO:Cr,Sm nanoparticles to be utilised as a drug carrier and the drug release results indicate that the GAO:Cr,Sm drug carriers have an excellent drug sustained properties. Applying the Cr 3+ and Sm 3+ coped with gadolinium aluminate as the NIR persistent luminescence center and the energy transfer resonance from Gd 3+ to Cr 3+ , these nanoparticles exhibit excellent NIR persistent luminescence at 732 nm under the UV irradiation of 254 nm and it can persist for about half an hour. In addition, they possess a longitudinal relaxivity (r 1 ) value of 4.75 mM −1 s −1 , which means that these nanoparticles could be applied for MR imaging as contrast agents. Carboxymethyl Chitosan was modified on the surface of GAO:Cr,Sm nanoparticles to make them owning excellent biocompatibility and low toxicity and these nanoparticles were successful to realize in vivo imaging. Hence, the well-defined nanoprobes of GAO:Cr,Sm exhibit great potential in biomedicine as trackable drug carriers and in vivo imaging agent due to the dual-model imaging property. [ABSTRACT FROM AUTHOR]

This paper describes the development of an entirely remote, portable, and low-cost sensor system that includes a mechanoluminescence (ML) sample, optical sensor, and wireless data transmitter module. A composite consisting of SrAl 2 O 4 :Eu,Dy and epoxy resin was used as the ML test sample. The performance of the ML system, including the wireless function and accuracy, were tested under laboratory conditions. The wireless module was confirmed to provide reliable synchronous data transmission. The ML sensor system was then utilized to measure the stress of an object in a practical application. The ML data were easily acquired even with an applied load of 300 N and eventually stabilized with continuous load cycles. The ML system was able to detect a crack in a gas pipeline during operation with high sensitivity. The combined results indicate that the designed ML sensor system can potentially be applied as a smart and wireless structural health monitoring system. [ABSTRACT FROM AUTHOR]

Multifunctional nanoplatforms with multimodal imaging and cancer therapy capabilities have attracted attention in biomedical applications. Near-infrared persistent luminescence nanoparticles (NPLNPs) were considered one of the most promising candidates for constructing multifunctional nanoplatforms due to the absence of in situ excitation and high signal-to-noise ratios (SNRs). Here, we report a novel NPLNP mSiO 2 @Gd 3 Ga 5 O 12 :Cr 3+ , Nd 3+ (mSiO 2 @GGO) as multifunctional nanoplatforms for multimodal imaging and cancer therapy. These NPs exhibited a persistent luminescence (745 nm) of more than 3 h in the first near-infrared window (NIR-I) after UV excitation, which can realize high SNRs and long-term in vivo imaging. Moreover, these NPs showed excellent NIR luminescence (1067 nm) in the second near-infrared window (NIR-II) under 808 nm excitation, which is more suitable for deep tissue imaging due to the lower photon scattering and deeper tissue penetration of NIR-II luminescence. Furthermore, the host Gd 3 Ga 5 O 12 with high Gd 3+ concentration showed a high r 1 value (10.70 mM −1 s −1 ) and was suitable for T 1 MR imaging. The mesoporous silica nanoparticles (mSiO 2 ) served as a framework to control the mSiO 2 @GGO particle morphology and provide low toxicity and drug loading capacity for cancer therapy. [ABSTRACT FROM AUTHOR]

Obvious enhancement of blue mechanoluminescence (ML) has been observed for Sr n MgSi 2 O 5+n :Eu (1 ≤ n ≤ 2) (SMSE) fabricated via systematically controlling the defective phases. The existence of defective phases affects not only the concentration of trap centers but also the structure of SMSE. The dependence between ML intensity and thermoluminescence integrated intensity showed that the trap centers created by defective phase play an important role in producing the ML of SMSE. Furthermore, when the effect of trap centers on ML eliminated to the smallest, the sample with the easiest deformation structure possessed the highest ML intensity. The strong piezoelectric ability induced by the existence of defective phase is responsible for this phenomenon. These results indicate that the origin of ML is piezoelectricity-induced electroluminescence, that is, piezoelectricity impelled the trapped electrons to escape from the traps and produce ML. [ABSTRACT FROM AUTHOR]

A near-infrared luminescent material LiGaSiO 4 :Cr3+ with triple temperature detection function was synthesized in this paper. The results show that the sample has the best Near-infrared luminescence (NIR) performance under the excitation of 620 nm red light when the concentration of Cr3+ is 0.05%. The emission peak in the near infrared region (705 and 721 nm) is due to the 2E→4A 2 energy level transition of Cr3+, and the emission peak in the red region (670 nm) is due to the 4T 2 →4A 2 energy level transition of Cr3+. The obtained results show that the dependences of temperature on three fluorescence intensity ratio (FIR) models including 670/705, 705/721 and 721/605 all show excellent linearity, indicating that high temperature sensing sensitivity and accuracy can be obtained via the combination of three FIR models. Furthermore, FIR (705 / 721) can provide the highest temperature sensing performance and its relative sensitivity (S r) is up to 4.32 K-1. All these results indicate LiGaSiO 4 : Cr3+ possessed great potential in the application of temperature sensing. • A near-infrared luminescent material LiGaSiO 4 :Cr3+ with triple temperature detection function was synthesized. • LiGaSiO 4 :Cr3+ phosphors showed excellent temperature sensing sensitivity and accuracy. • The relative temperature sensitivity of LiGaSiO 4 :Cr3+ is up to 4.32 K-1 [ABSTRACT FROM AUTHOR]

In this paper, sensitive mechanoluminescence (ML) phosphors Sr 3 Al 2 O 5 Cl 2 :Eu2+, Tm3+ have been developed. The effect of co-doped Tm3+ ions on the ML properties of the samples were investigated. The results showed that the ML emission, afterglow emission and photoluminescence were similar all consisted of a broad band peated at 610 nm, which can be ascribed to the 4f65 d1→4f7 transition of Eu2+. This result indicated that the ML also originated from the Eu2+ emitting center not the Tm3+ ions. The thermoluminescence and ML results have confirmed that the shallow traps (0.656 eV) created by the Tm3+ ions answered for the origin of sensitive ML. Furthermore, following the increase of co-doped Tm3+ ions, the density of shallow trap increased greatly, which brought out strong sensitive ML intensity accordingly. When the content of Tm3+ reached 0.05, sensitive ML intensity of the sample arrived at the strongest under the compressive load of 10–50 N. In addition, the obtained results also showed that the deep traps can provide the possibility to produce long time stable ML emission under strong compressive load of 10–800 N. Even after 120 min, stable obvious ML signals can be observed. All these results suggested that Sr 3 Al 2 O 5 Cl 2 :Eu2+, Tm3+ phosphors possessed great potential in precious detection of weak stress and long time stable ML detection. • Sr 3 Al 2 O 5 Cl 2 :Eu2+, Tm3+ showed sensitive mechanoluminescence under the compressive load of 10–50 N. • Sr 3 Al 2 O 5 Cl 2 :Eu2+, Tm3+ showed long time stable mechanoluminescence emission even after 120 min. • The shallow traps were responsible for the sensitive mechanoluminescence. [ABSTRACT FROM AUTHOR]

Abstract: A series of new luminescent phosphors SrMgSi2O6:Ce,Tb have been prepared by a solid state reaction method. The phase characterizations, luminescence emission and excitation spectra and optimum doping concentrations of the SrMgSi2O6:Ce,Tb phosphors are investigated in detail. The intense green emission monitored at 542nm is realized in the SrMgSi2O6: Ce, Tb phosphors on the basis of the highly efficient energy transfer from Ce3+ to Tb3+. The energy transfer mechanism is ascribed to the dipole–dipole interaction. When the Tb3+ ion concentration was increased to 0.05, the transfer efficiency increased to 77%. The critical distance of the energy transfer has been calculated by the concentration quenching method. [Copyright &y& Elsevier]

In this paper, a novel long afterglow green luminescent material of Ga 4 GeO 8 : Tb3+ has been successfully synthesized by high-temperature solid-state method. Ga 4 GeO 8 showed long afterglow blue emission peaked at 490 nm. When Tb3+ ions were introduced into the host, the strong long afterglow green emission from the f-f transition of Tb3+ appeared and the blue afterglow emission of the host disappeared completely. Furthermore, the obtained results have shown that the afterglow emission of the host overlapped with typical excitation wavelengths of Tb3+ in the range 300–500 nm, indicating of persistent energy transfer from the host to Tb3+ ions. The thermoluminescence curves monitored at 490 and 550 nm belonged to the afterglow emissions of host and Tb3+ respectively were similar, which consisted of two peaks at T A (303 K) and T B (350 K) corresponded to the shallow trap and the deep trap and the trap depths were estimated to be 0.606 and 0.732 eV. This further confirmed that the persistent energy transfer form host to Tb3+ ions was responsible for the excellent long afterglow green luminescence of Ga 4 GeO 8 : Tb3+. Thus, the efficient persistent energy transfer of host to emitting center can be regarded as an effective strategy to realize more colors novel long afterglow luminescent materials. • Novel long afterglow green luminescent material of Ga 4 GeO 8 : Tb3+ was developed. • The persistent energy transfer from host to Tb3+ resulted in afterglow emission. • The appropriate trap depths answered for good afterglow luminescent performance. [ABSTRACT FROM AUTHOR]

Owning to exceptional optical and physicochemical properties, lanthanide-doped inorganic dual-mode luminescence materials are regarded as promising platform for multifunctional applications. Herein, a facile hydrothermal method is used to integrate Ce3+ and Nd3+ ions co-doped NaLuF 4 phosphors, achieving dual-mode with ultraviolet (UV) and the second near-infrared (NIR-II) luminescence from single particles under two excitation sources. Higher NaF/LnCl 3 ratio can not only promote the crystal phase transformation from cubic to hexagonal and the shape evolution from nanoparticles to microprisms, but also promote the UV and NIR-II luminescence properties of NaLuF 4 :Ce3+, Nd3+ phosphors. Upon irradiation with X-ray, Ce3+ and Nd3+ ions co-doped NaLuF 4 phosphors exhibit strong broad band UV emission due to 5d → 4f transition emission of Ce3+. Under 808 nm NIR excitation, the phosphors give NIR-II emission with two peaks at around 1060 nm and 1340 nm, which are attributed to the 4F 3/2 → 4I 11/2 and 4F 3/2 → 4I 13/2 electron transitions of Nd3+ ions respectively. Furthermore, the possible emission and energy transfer mechanism between Ce3+ and Nd3+ under the excitation of X-ray and 808 nm laser are discussed in details. The above results not only pave the way for future research of dual-mode luminescent materials, but also endow such materials with potential bio-applications for deep tissue bioimaging and therapy. • The NaF/LnCl 3 ratio can adjust the morphology and phase of NaLuF 4 :Ce3+, Nd3+. • Achieving dual-mode luminescence under the excitation of X-ray and 808 nm laser. • Energy transfer mechanism between Ce3+ and Nd3+ ions was proposed. • Having great potential for dual-mode deep tissue bioimaging and therapy. [ABSTRACT FROM AUTHOR]

In this paper, we have designed dual-mode imaging agents LuOF: Nd3+ NPs, which can provided bimodality imaging of NIR-to-NIR-II luminescence and X-Ray computed tomography. The as-prepared samples prepared by hydrothermal method possessed irregular paving stone shapes with size distribution of 10–15 nm. The structure analysis showed the samples were pure cubic phase. Under the excitation of 808 nm laser (power of 500mW/cm2), Lu 0.99 OF: 0.01Nd3+ NPs exhibited excellent NIR-II luminescence, which main peak located at 1053 nm and NIR emission intensity reached 3.0 × 105 cps. At the same time, the X-ray attenuation value was 100HU when the content of Lu 0.99 OF: 0.01Nd3+ NPs was only 10 mg/mL. And, the MTT arrays have confirmed the excellent biological safety of Lu 0.99 OF: 0.01Nd3+ NPs. Furthermore, the in vivo imaging results have confirmed that Lu 0.99 OF: 0.01Nd3+ NPs possessed not only NIR–II luminescent deep tissue in vivo imaging ability but also good computed tomography imaging ability. All these results indicated that LuOF: Nd3+ NPs can be regarded as dual-mode imaging agents in future medical field. • Dual-mode imaging agents LuOF: Nd3+ nanoparticles were developed. • LuOF: Nd3+ nanoparticles exhibited excellent NIR-II luminescence. • LuOF: Nd3+ nanoparticles possessed high X-ray attenuation value. [ABSTRACT FROM AUTHOR]