X-ray Excited Luminescence Research Articles

High Performance Dynamic X-ray Flexible Imaging Realized Using a Copper Iodide Cluster-Based MOF Microcrystal Scintillator.

X-ray imaging technology has achieved important applications in many fields and has attracted extensive attentions. Dynamic X-ray flexible imaging for the real-time observation of the internal structure of complex materials is the most challenging type of X-ray imaging technology, which requires high-performance X-ray scintillators with high X-ray excited luminescence (XEL) efficiency as well as excellent processibility and stability. Here, a macrocyclic bridging ligand with aggregation-induced emission (AIE) feature was introduced for constructing a copper iodide cluster-based metal-organic framework (MOF) scintillator. This strategy endows the scintillator with high XEL efficiency and excellent chemical stability. Moreover, a regular rod-like microcrystal was prepared through the addition of polyvinyl pyrrolidone during the in situ synthesis process, which further enhanced the XEL and processibility of the scintillator. The microcrystal was used for the preparation of a scintillator screen with excellent flexibility and stability, which can be used for high-performance X-ray imaging in extremely humid environments. Furthermore, dynamic X-ray flexible imaging was realized for the first time. The internal structure of flexible objects was observed in real time with an ultrahigh resolution of 20 LP mm-1 .

High Performance Dynamic X‐ray Flexible Imaging Realized Using a Copper Iodide Cluster‐Based MOF Microcrystal Scintillator

AbstractX‐ray imaging technology has achieved important applications in many fields and has attracted extensive attentions. Dynamic X‐ray flexible imaging for the real‐time observation of the internal structure of complex materials is the most challenging type of X‐ray imaging technology, which requires high‐performance X‐ray scintillators with high X‐ray excited luminescence (XEL) efficiency as well as excellent processibility and stability. Here, a macrocyclic bridging ligand with aggregation‐induced emission (AIE) feature was introduced for constructing a copper iodide cluster‐based metal–organic framework (MOF) scintillator. This strategy endows the scintillator with high XEL efficiency and excellent chemical stability. Moreover, a regular rod‐like microcrystal was prepared through the addition of polyvinyl pyrrolidone during the in situ synthesis process, which further enhanced the XEL and processibility of the scintillator. The microcrystal was used for the preparation of a scintillator screen with excellent flexibility and stability, which can be used for high‐performance X‐ray imaging in extremely humid environments. Furthermore, dynamic X‐ray flexible imaging was realized for the first time. The internal structure of flexible objects was observed in real time with an ultrahigh resolution of 20 LP mm−1.

Optimizing crystallinity to enhance X-ray excited persistent luminescence intensity of NaLuF4: Gd/Tb nanoparticles

Lanthanide doped fluoride nanoparticles (NPs) exhibit tunable X-ray excited persistent luminescence (XEPL), which show promising applications in optical imaging, cancer therapy and information storage. Although a few progresses have been achieved in enhancing the XEPL of lanthanide activators, there is no report about the influence of crystallinity on the XEPL intensity. In this work, we verify that the XEPL intensity can be improved by optimizing the NP crystallinity. Our results reveal that better crystallinity benefit the lower non-radiative relaxation possibility but also the restriction of the formation of Frenkel defects. This work provides important information for the development of lanthanide doped fluoride nanoparticles with superior XEPL performances.

Luminescence properties of CsPbBr3 single crystals and CsPbBr3 crystalline phases dispersed in a KBr matrix

Spectra of steady-state X-ray excited luminescence (XEL) and thermally stimulated luminescence (TSL) of CsPbBr3 single crystals in the temperature range of 80–294 K were studied. Each of the measured XEL spectra of CsPbBr3 single crystal contain only one elementary band peaking at 535 nm, which can be attributed to the radiative decay of the matrix exciton. The activation energy of exponential luminescence thermal quenching in this range, as determined by Mott's formula, is equal to 75 meV, close to the hole trap depth of 110 meV obtained for the main TSL peak of this crystal at 125 K. This value of the XEL quenching activation energy is associated with the thermal deactivation of the exciton hole component in the CsPbBr3 matrix.Doping of KBr crystals with CsPbBr3 perovskite impurities (0.05–1 mol. %) leads to the formation of CsPbBr3 micro- and nanocrystals in a KBr matrix with characteristic spectra of exciton photo- and XEL luminescence. A five-fold increase in the intensity of XEL was registered in KBr: CsPbBr3 (0.05 mol. %) samples at 294 K compared to that of CsPbBr3 single crystal.The temperature dependence of the XEL intensity of KBr: CsPbBr3 crystals and the analysis of their TSL integral curves allow us to make a conclusion about the hole mechanism of high-energy excitation energy transfer from the matrix to the activator resulting in the appearance of typical exciton luminescence in CsPbBr3 nanoparticles.

Evaluation of the Structural, Near-Infrared Luminescence, and Radioluminescence Properties of Nd3+ Activated TTB-Lead Metatantalate Phosphors

The study reports the structural and spectroscopic properties of Nd3+ doped lead metatantalate phosphor series fabricated by conventional solid state method. XRD results of the PbTa2O6 phase confirm the tungsten bronze symmetry and single-phase structure between 0.5 and 10 mol% Nd3+ concentrations. The lead decrease in the structure can be associated with maintaining the charge balance and single phase due to evaporation during sintering. In SEM micrographs, the grains exhibited shapeless morphology, and the grain sizes varied from 0.5 to 7 m. In EDS results, the increase of Ta/Pb ratio in grain surfaces indicated some lead evaporation, as reported in previous studies. The absorption spectrum of PbTa2O6 host peaked around 275-280 nm, and the band gap was found to be 3.7±0.2 eV. The absorptions of Nd3+ doped phophors shifted the high wavelenght or the low band gap, where the band gaps were found between 3.1±0.2 and 3.3±0.2 eV. The PL emissions of the phosphors in near-inrared region were observed with the transitions of 4F3/2→4I9/2 (at 875 nm) and 4F3/2→4I11/2 (at 1060 nm) of Nd3+. The RL emissions or X-ray excited luminescence were monitored with the transitions of 4F3/2→4I9/2 (at 875 nm), 4F3/2→4I11/2 (at 1065 nm) in the infrared region, and the transitions of 2F(2)5/2→4F9/2, 2F(2)5/2→2H(2)11/2, 2F(2)5/2→4G5/2, 2F(2)5/2→4G7/2, 2F(2)5/2→4G9/2 in the visible region corresponding to at around 430, 455, 490, 525, and 570 nm, respectively. PL and RL emissions of the phosphors exhibited the decreasing emission intensity over 5 mol% due to the concentration quenching which may be associated with cross-relaxing mechanism. In the PL and RL spectral profiles, the similarity of splitting levels was attributed to the similarity of the local symmetry of the ligand ions surrounding the Nd3+ ion. The CIE coordinates obtained using RL emissions were found close to the blue region due to visible region transitions.

Solvothermal synthesis of rhombic shape GdF<sub>3</sub>:Tb<sup>3+</sup> nanoparticles for biomedical applications

Purpose of the study. In this work, we have investigated the mechanism of structure formation of GdF3:Tb3+(15 %) nanocrystals synthesized by solvothermal synthesis in the temperature range from RT to 200 °C with a step of 50 °C.Materials and methods. Nanocrystals of GdF3:Tb3+(15 %) were synthesized by the solvothermal method using a high-pressure reactor (autoclave) designed for temperatures up to 250 °C. The structure, size and morphology were determined by transmission electron microscopy (TEM), the type of crystal lattice and the size of crystallites of nanoparticles were studied by X-ray diffraction (XRD), hydrodynamic size of nanoparticles, particle size distribution, ζ-potential, agglomeration of nanoparticles in colloidal solutions were determined by dynamic light scattering (DLS), the chemical composition of the nanocrystals surface was studied by Fourier-t ransform infra-red spectroscopy (FT-IR), the nanoparticles ability to absorb UV radiation was analyzed by UV-visible spectroscopy (UV-vis) and X-ray excited optical luminescence (XEOL).Results. With an increase in the temperature of the synthesis reaction, a structural change in the crystallites phase occurs from hexagonal to orthorhombic. At low temperatures, agglomerated particles consisting of hexagonal nanocrystals are formed, while at a temperature higher than the boiling point of the solvent, monodisperse rhombic- shaped nanoparticles with orthorhombic phase are formed. At mild temperatures, agglomerated particles with different morphology and with mixed hexagonal and orthorhombic phases are formed. Based on the analysis of X-ray spectrum, it was found that the size of GdF3:Tb3+(15 %) nanocrystals varies from 10 to 50 nm for different synthesis temperature conditions (T = RT, 50 °C, 100 °C, 150 °C, 200 °C). The hydrodynamic size of nanoparticles decreases with increasing synthesis temperature. All GdF3:Tb3+(15 %) nanocrystals obtained at different temperatures are transparent to visible light and absorb UV radiation. Absorption in the UV region increases with an increase in the size of particle crystallites. Upon X-ray irradiation of the colloidal GdF3:Tb3+(15 %) solution, X-ray excited optical luminescence spectra showed emission peaks at 490 nm, 543 nm, 585 nm and 620 nm.Conclusion. The mechanism of structure formation of rhombic‑ shaped GdF3:Tb3+(15 %) nanocrystals has been investigated. These monodisperse rhombic- shaped nanoparticles can be used for X-ray induced photodynamic therapy (X-PDT) of superficial, solid and deep-seated tumors.

Study on luminescent performance of Dy3+-, Tb3+-doped and Tb3+/Dy3+ co-doped TeO2-(Gd,Lu)2O3-WO3 glass scintillators

Three series of Dy3+-, Tb3+-doped and Tb3+/Dy3+ co-doped 40TeO2-20(Gd,Lu)2O3–40WO3 glasses with density of about 6.75 g/cm3 were successfully prepared by high temperature melt-quenching method. The luminescence properties of these rare earth ions doped 40TeO2-20(Gd,Lu)2O3–40WO3 glass were systematically studied by transmittance, photoluminescence (excitation and emission spectra), time-resolved emission spectra (TRES) and X-ray excited luminescence (XEL) spectra, together with the luminescence decay curves. The optimal doping concentration of Dy3+ and Tb3+ ions in 40TeO2-20(Gd,Lu)2O3–40WO3 glasses was determined under UV and X-ray excitation, respectively. It is found there is an efficient energy transfer from Dy3+ to Tb3+ ions in 40TeO2-20(Gd,Lu)2O3–40WO3 glass in photoluminescence spectra. However, it is not true under X-ray excitation due to the complicated physical process.

A novel scintillating material based on Cu+ doped borate glass

Luminescence glass is an inspiring scintillating material because of the unique merits including simple preparation process, mass production and low-cost. However, it is still a daunting challenge to explore the scintillating glass which can be applied in practical life. Herein, a novel Cu + doped borate glass scintillator was successfully fabricated under air atmosphere by introducing proper Si3N4 in melting process. The resultant glass exhibits broadband luminescence under ultraviolet (UV) light or X-ray excitation. Through the low temperature thermal treatment, both luminescence induced by UV and X-ray can be further enhanced. The quantum efficiency reaches as high as 74.2%. And the sample endows superior thermal stability with the emission intensity at 573 K still maintaining 62.5% of that at 303 K. The X-ray excited luminescence is 37.8% of that of the commercial Bi4Ge3O12 (BGO) crystal. Furthermore, the damaged sample even stimulated by high-energy X-ray can be restored to original level completely after heat treatment again. Besides, the sample presents outstanding optical thermometric performance based on the fluorescence decay lifetime. These findings confirm that the as-prepared Cu+ doped borate glass is a promising candidate applied in the areas of scintillator and temperature sensor.

Lanthanide and yttrium substitution in natural fluorite

Fluorite is one of the most common minerals in the crust and is of widespread economic importance. It shows strong UV-excited luminescence, variously attributed to defects within the fluorite structure and lanthanide substitutions. We present here a detailed chemical characterisation of a suite of natural fluorite samples, chosen to represent the range of compositions observed in nature. We perform X-ray excited luminescence spectroscopy on the samples as a function of temperature (20–673 K) in the wavelength range 250–800 nm to provide insights into physical defects in the lattice and their interactions with lanthanide substituents in natural fluorite. Most broad bands in the UV are attributed to electronic defects in the fluorite lattice, whereas sharp emissions are attributed to intra-ion energy cascades in trivalent lanthanides. Lanthanides are accommodated in fluorite by substitution for Ca2+ coupled with interstitial F−, O2− (substituting for F−) and a variety of electronic defect structures which provide local charge balance. The chondrite-normalised lanthanide profiles show that fluorite accommodates a greater proportion of heavy lanthanides (and Y) as the total Rare Earth Element (REE) concentration increases; whereas cell parameters decrease and then increase as substitution continues. Luminescence intensity also goes through a maximum and then decreases as a function of REE concentration. All three datasets are consistent with a model whereby lanthanides initially act as isolated centres, but, beyond a critical threshold (~ 1000 ppm), cluster into lanthanide-rich domains. Clustering results in shorter REE-O bond distances (favouring smaller heavier ions), a larger unit cell but more efficient energy transfer between lanthanides, thereby promoting non-radiative energy loss and a drop in the intensity of lanthanide emission.

Structural and Scintillation Properties of Ce3+:Gd3Al3Ga2O12 Translucent Ceramics Prepared by One-Step Sintering.

Cerium-doped gadolinium aluminum gallium garnet (Ce3+:Gd3Al3Ga2O12, Ce3+:GAGG) ceramic is a promising scintillation material. In this study, Ce3+:Gd3Al3Ga2O12 scintillation ceramics were prepared by the one-step sintering of commercially available Gd2O3, Al2O3, Ga2O3, and CeO2 powders in a flowing oxygen atmosphere at 1600 °C by solid-phase reaction sintering. For all the Ce3+:Gd3Al3Ga2O12 ceramic samples doped with different amounts of Ce3+ doping, dense ceramics were obtained. The structure, photoluminescence, and scintillation properties of the Ce3+:Gd3Al3Ga2O12 ceramics have been investigated. The average grain size of samples sintered at 1600 °C is about 2 μm. The X-ray excitation luminescence peak is around 560 nm, which is consistent with that of Ce3+:Gd3Al3Ga2O12 single crystals, matching well with the computed tomography X-ray detector's response sensitivity. The light yield is higher compared to the standard reference sample-lutetium yttrium orthosilicate single crystal.

Effects of Preparation Atmosphere and Doping Concentration on Scintillation and Photoluminescence Properties of Lu2O3:Eu Scintillation Single Crystals

Lu2O3:1%Eu and Lu2O3:8%Eu series single crystals were grown by optical floating zone method under air, N2, and H2-Ar mixed atmosphere (5 vol%H2 and 95 vol%Ar). The effects of preparation atmosphere and doping concentration on the scintillation and photoluminescence properties have been investigated and discussed. Correlated measurements of afterglow curves, X-ray excited luminescence spectra, photoluminescence excitation and photoluminescence, photoluminescence decay, and thermal stimulated luminescence curves were performed. Although Eu(S6) luminescence can be significantly depressed under oxidizing atmosphere, Lu2O3:8%Eu grown under weak reducing atmosphere presents the lowest afterglow intensity. This phenomenon was explained by different interstitial oxygen atom concentrations in the samples.

Development of a red persistent luminescent composite: Electrospun nanofiber polymer coating prevents emission quenching by water

Sulfide persistent luminescent materials are known for their efficient luminescence, although a limitation in application of these materials is their susceptibility to hydrolysis. In this work, the electrospinning technique was used to encapsulate polycrystalline SrS:Eu2+,Sm3+ within PVDF-co-HFP nanofibers, after which thermostimulated luminescence could be observed with the naked eye following treatment with boiling water, confirming that the storage capacity of the powder was maintained after encapsulation. The composite material presented high levels of flexibility, hydrophobicity, and thermal and chemical stability. The structural characteristics of the synthesized SrS:Eu2+,Sm3+ were elucidated using X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The morphologies of the SrS:Eu2+,Sm3+ grains and the electrospun nanofibers were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray fluorescence (XRF) mapping, and scanning transmission X-ray microscopy (STXM). Mechanical properties including elastic modulus and deformation degree were evaluated by PeakForce quantitative nanomechanical mapping (PF-QNM). The luminescent properties were investigated using photoluminescence spectroscopy (PLS), diffuse reflectance spectroscopy (DRS), and X-ray excited optical luminescence (XEOL), which showed that the photonic functionality of the material in the nanofibers was preserved, even after severe treatment with boiling water.

Cationic Effects on Photo- and X-ray Radioluminescence of K3RE(PO4)2:Ce3+/Pr3+(RE = La, Gd, and Y) Phosphors toward X-ray Detection

Cationic tuning for lanthanide (Ce3+/Pr3+)-activated inorganic phosphors with stable, efficient, and fast-decay 5d-4f emissions has emerged as an important strategy toward the continuing pursuit of superior scintillators. The in-depth understanding of the cationic effects on photo- and radioluminescence of lanthanides Ce3+ and Pr3+ centers is requisite for the rational cationic tuning. Here, we perform a systematic study on the structure and photo- and X-ray radioluminescence properties of K3RE(PO4)2:Ce3+/Pr3+ (RE = La, Gd, and Y) phosphors to elucidate the underlying cationic effects on their 4f-5d luminescence. By using the Rietveld refinements, low-temperature synchrotron-radiation vacuum ultraviolet-ultraviolet spectra, vibronic coupling analyses, and vacuum-referred binding energy schemes, the origins of lattice parameter evolutions, 5d excitation energies, 5d emission energies, and Stokes shifts as well as good emission thermal stabilities of K3RE(PO4)2:Ce3+ systems are revealed. In addition, the correlations of Pr3+ luminescence to Ce3+ in the same sites are also discussed. Finally, the X-ray excited luminescence manifests that the K3Gd(PO4)2:1%Ce3+ sample possesses a light yield of ∼10,217 photons/MeV, indicating its potentiality toward X-ray detection application. These results deepen the understanding of cationic effects on Ce3+ and Pr3+ 4f-5d luminescence and inspire the inorganic scintillator development.

Synthesis and optical properties of phosphorus doped ZnO: X-ray absorption, X-ray emission, and X-ray excited optical luminescence studies

Abstract Over the past decades, zinc oxide semiconductor and its derivatives have been extensively developed because of its optoelectronic properties. Since ZnO is an intrinsic n-type semiconductor, how to synthesize high-quality p-type ZnO semiconductors and investigate their optoelectronic properties and local chemical structures are important and necessary. In this article, two studies of synthesizing both undoped and phosphorus-doped ZnO nanostructures by hydrothermal method and chemical vapor deposition (CVD) technique are presented. Scanning electron microscopy (SEM) and laboratory X-ray diffraction (XRD) are used to track the surface morphology and the crystalline structure of both undoped and phosphorus doped ZnO nanostructures, respectively. X-ray absorption near edge structures (XANES), X-ray emission spectroscopy (XES) and X-ray excited optical luminescence (XEOL) are also used to determine the local chemical information of both undoped and phosphorus-doped ZnO nano/microstructures such as local symmetry and optical properties. It is found that the phosphorus is successfully doped into the surface of ZnO and substituted the Zn. The phosphorus-doped ZnO products have better crystallinity and less oxygen vacancies on the surface. These two are correlated as one leads to the other. The XEOL results suggest that the average bandgap for undoped and phosphorus doped ZnO is the same, 3.24 eV. The second derivative of the absorption-emission spectra yields the fundamental bandgap for undoped ZnO and phosphorus-doped ZnO is 3.25 eV. The implication of this observation is discussed.

Effect of B2O3 on luminescence and scintillation properties of Ce3+-doped gadolinium aluminium–silicate glass

Different B2O3 content was added to Ce3+–doped Gd2O3–Al2O3–SiO2 (xBGAS:1.1Ce3+, x = 0, 5, 10, 15) glasses to improve the photoluminescence (PL) and scintillation properties. The transmittance of 15BGAS:1.1Ce3+ glass is over 80%. The X–ray absorption near edge spectroscopy (XANES) spectra imply that Ce4+ can be effectively reduced to Ce3+ in the glasses by adding Si3N4. The excitation and emission spectra show a blue shift with increase of B2O3 content. The photoluminescence quantum yield (PL QY) increases with the increase of B2O3 content, reached the maximum of 59.55% when x = 15. The PL decay time of the glasses exhibits typical values (44–50 ns) due to 5d→4f transition of Ce3+ ions. The PL thermal activation energy become larger, indicating that xBGAS:1.1Ce3+ glasses have better luminescent thermal stability. The integral X–ray excited luminescence (XEL) intensity of the 15BGAS:1.1Ce3+ glass is 37.38% of Bi4Ge3O12 (BGO) crystal, and the light yield is 1267 ph/MeV with an energy resolution of 23.22% at 662 keV when exposed to γ–rays. With the increase of B2O3 content, the fast component of scintillation decay time gradually becomes shorter and the slow component becomes longer. The thermally stimulated luminescence (TSL) curves were measured to investigate the trap depth and density of defects in xBGAS:1.1Ce3+ glasses.

Growth phase diagram and X-ray excited luminescence properties of NaLuF4:Tb3+ nanoparticles

X-rays are energy sources exhibiting extended penetration depths, and they have attracted increasing attention in industry and for clinical application. With the rapid development of nanomaterials and X-ray excited luminescent nanoparticles (XLNPs), new modalities for bioimaging and cancer therapy have been developed, such as X-ray luminescent computed tomography (XLCT) and X-ray excited photodynamic therapy (X-PDT). To meet the requirements of biomedical applications, XLNPs must exhibit high luminescence intensities, appropriate size distributions (less than100 nm) and negligible cytotoxicity. Due to the optical properties associated with f-electrons, rear earth (RE) elements are highly suitable for creating XLNPs. NaREF4 nanoparticles (NPs) have been shown to be suitable hosts with high luminescence intensities, controllable sizes, and biocompatibility for X-ray-based biomedical applications. Syntheses of NaLuF4 NPs doped with rare earth elements for upconversion applications have been systematically studied. However, for X-ray excited applications, the doping levels of the NPs must be totally different, which greatly affects the morphologies and sizes of the NaLuF4 NPs. Thus, in this paper, nucleation, phase transitions, morphologies and sizes, and luminescence properties of Tb3+-doped NaLuF4 NPs were systematically studied. OA-capped NaLuF4:Tb3+ NPs were synthesized via coprecipitation processes with different reaction temperatures and reaction times to study the nucleation mechanism systematically, and the morphologies, size distributions and crystal phases were characterized with TEM and XRD. The morphologies, size distributions and crystal phases of these NPs were seriously influenced by the reaction temperature and reaction time. At 295 ℃, the NP sizes increased with prolonged reaction time, and the crystalline phase was a mixture of cubic and hexagonal phases. At 300 ℃ and 310 ℃, the pure hexagonal phase was obtained after 20 min and 35 min reaction times, respectively. The luminescence strengths of these NPs were associated with the particle sizes, crystalline phases, and Tb3+ doping levels. Stronger luminescence was achieved with larger particle sizes and purer hexagonal crystal phases. In addition, the 15 % doping level for Tb3+ provided the maximum luminescence intensity. The present work provides insights into the mechanism of NaLuF4:Tb3+ nanocrystal growth.

Ce 3+:Lu 3Al 5O 12–Al 2O 3 optical nanoceramic scintillators elaborated via a low-temperature glass crystallization route

Transparent Ce:lutetium aluminum garnet (Ce:Lu₃Al₅O₁₂, Ce:LuAG) ceramics have been regarded as potential scintillator materials due to their relatively high density and atomic number (<i>Z</i>_eff). However, the current Ce:LuAG ceramics exhibit a light yield much lower than the expected theoretical value due to the inevitable presence of Lu_Al antisite defects at high sintering temperatures. This work demonstrates a low-temperature (1100 ℃) synthetic strategy for elaborating transparent LuAG–Al₂O₃ nanoceramics through the crystallization of 72 mol% Al₂O₃–28 mol% Lu₂O₃ (ALu28) bulk glass. The biphasic nanostructure composed of LuAG and Al₂O₃ nanocrystals makes up the whole ceramic materials. Most of Al₂O₃ is distributed among LuAG grains, and the rest is present inside the LuAG grains. Fully dense biphasic LuAG–Al₂O₃ nanoceramics are highly transparent from the visible region to mid-infrared (MIR) region, and particularly the transmittance reaches 82% at 780 nm. Moreover, Lu_Al antisite defect-related centers are completely undetectable in X-ray excited luminescence (XEL) spectra of Ce:LuAG–Al₂O₃ nanoceramics with 0.3–1.0 at% Ce. The light yield of 0.3 at% Ce:LuAG–Al₂O₃ nanoceramics is estimated to be 20,000 ph/MeV with short 1 μs shaping time, which is far superior to that of commercial Bi₄Ge₃O₁₂ (BGO) single crystals. These results show that a low-temperature glass crystallization route provides an alternative approach for eliminating the antisite defects in LuAG-based ceramics, and is promising to produce garnet-based ceramic materials with excellent properties, thereby meeting the demands of advanced scintillation applications.

Probing size-dependent defects in zinc oxide using synchrotron techniques: impact on photocatalytic efficiency.

In the present study, synchrotron-based X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and X-ray excited optical luminescence (XEOL) have been used to investigate the induced defect states in metal oxide nanomaterials. Specifically, two synthesis approaches have been followed to develop unique nano-sized peanut-shaped (N-ZnO) nanostructures and micron-sized hexagonal rods (M-ZnO). XANES analysis at the Zn K-edge revealed the presence of defect states with a divalent oxidation state of zinc (Zn2+) in a tetrahedral structure. Furthermore, XAS measurements performed at the Zn L3,2-edge and O K-edge confirm higher oxygen-related defects in M-ZnO, while N-ZnO appeared to have a higher concentration of surface defects due to size confinement. Moreover, the in-line XEOL and time dependent-XEOL measurements exposed the radiative excitonic recombination phenomena occurring in the band-tailing region as a function of absorption length, X-ray energy excitation, and time. Based on the chronology developed in the defect state improvement, a possible energy band diagram is proposed to accurately locate the defect states in the two systems. Furthermore, the increased absorption intensity at the Zn L3,2-edge and the O K-edge under the UV lamp suggests delayed recombination of electrons and holes, highlighting their potential use as photo catalysts. The photocatalytic activity degrading the rhodamine B dye established M-ZnO as a superior catalyst with a rapid degradation rate and significant mineralization. Overall, this work provides valuable insights into ZnO defect states and provides a foundation for efficient advanced materials for environmental or other optoelectronic applications.

Preparation, morphology and luminescence properties of micro-columnar structured Lu2O3:Eu films by LCVD method on quartz glass

Micron/sub-micron hard X-ray imaging is an important development direction of X-ray detection technology. Scintillation screens with excellent X-ray stopping power and high light output are desired to obtain good imaging quality. Europium-doped lutetium oxide (Lu2O3:Eu) film with micro-columnar structure is an ideal candidate for this application. In this study, micro-columnar structured Lu2O3:Eu films were prepared on quartz glass substrates by laser chemical vapor deposition (LCVD) method. The influences of preparation conditions on structure and morphology properties of films were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Photoluminescence and scintillation properties of the films, including photoluminescence excitation (PLE), photoluminescence (PL), PL decay, X-ray excitation luminescence (XEL), and afterglow curves, were recorded. The relationships between structure, morphology, luminescence properties of films, and preparation conditions were investigated and discussed as well. The preparation conditions include laser power, oxygen flow rate, and precursor evaporation temperature. In addition, dual-layer Lu2O3:Eu film was prepared for the first time by just turning off the laser.

Photoluminescence and X‐Ray‐Induced Luminescence Behavior of Sm2O3‐Doped Oxyfluoroborate Scintillating Glass for Radiation Detecting Material

Various concentrations of samarium (Sm3+) ion‐activated oxyfluoroborate (ANCB:AlF3‐NaF‐CaF2‐B2O3) glasses are fabricated for its applications in red‐emitting lasers and scintillators. From the optical absorption spectrum, Ω2,4,6 intensity parameters and several radiative parameters along with the high value of absorption (2.96 × 10−21 cm2) and emission (14.13 × 10−22 cm2) cross sections are calculated. By stimulating at 403 nm, a transition corresponding to 4G5/2 → 6H7/2 (596 nm) is very intense and emits orange‐reddish luminescence of Sm3+ ion in ANCB glasses. The decay curves are fit to the Inokuti–Hirayama (I–H) model to determine the energy transfer in Sm3+: ANCB glasses. The X‐ray‐excited luminescence (XEL) spectra are determined with an X‐ray source by supplying the voltage of 50 kV and current 30 mA. The lasing parameters like stimulated emission cross section (14.13 × 10−22 cm2), optical gain (30.52 × 10−22 cm2 s), and quantum efficiency (80%) are found to be high for the 4G5/2 → 6H9/2 transition of Sm3+ ions. The quality of the emitted red light for the ANCBSm0.5 glass is calculated in terms of the (x, y) color coordinates and correlated color temperatures (CCT &lt; 3000 K). The integral scintillation efficiency of glasses shows the maximum value of 23% in comparison with Bi4Ge3O12 scintillation crystal.