X-ray Storage Research Articles

Phase control and energy-trapping management for high quality X-ray afterglow imaging

Long-persistent radioluminescence (RL) detectors have recently attracted extensive attention in healthcare diagnostics and nondestructive inspection due to their information storage capabilities. Nevertheless, the preparation and RL mechanisms of flexible ultralong-afterglow scintillators remain unexplored. Herein, we first introduce a dopant-driven phase control strategy to greatly enhance RL intensity and X-ray afterglow duration through suppressing the nonradiative recombination pathway and manipulating electron trap distribution in CsCdCl3: Mn2+/M (M = In3+, Sb3+, Bi3+) perovskite. The photophysical studies reveal the multiple energy transfer channels in multi-exciton emissive cubic (Cub.) CsCdCl3: In3+/Mn2+ and the tunability of trap depth ranging from 0.72 to 0.78 eV. Specially, the X-ray flexible detector based on Cub. CsCdCl3: In3+/Mn2+ achieves a low X-ray detection limit of 45.2 nGyair s−1, a high spatial resolution of 12.5 lp mm−1 and X-ray extension imaging longer than 10 h. These findings provide insight into RL dynamics and optimal storage performance, thereby contributing to motivate future research in X-ray storage detector.

Flexible X-ray Imaging and Stable Information Storage of SrF2:Eu Based on Radio-Photoluminescence.

X-ray imaging has garnered widespread interest in biomedical diagnosis and nondestructive detection. The exploration of radio-photoluminescence has hastened the advancement of X-ray information storage. However, significant challenges persist in achieving the prolonged imaging of curved objects without attenuation. Here, europium-doped strontium fluoride (SrF2:Eu) is meticulously created to exhibit a linear response to an extensive range of X-ray doses (maximum dose > 5000 Gy), showcasing excellent X-ray information reading/erasing reusability properties (10 cycles). This is accompanied by a red-to-blue emission transition under UV excitation, sustaining for 150 days without attenuation. To elucidate the phenomena of irradiated photoluminescent discoloration and the reversible X-ray storage of SrF2:Eu, we propose an electron-vacancy trap (valence conversion) mechanism, information stably retained by the SrF2:Eu-based device under ambient conditions due to high energy barriers. The time-lapse readout capability is further demonstrated for three-dimensional imaging of curved objects (10 lp mm-1) based on SrF2:Eu embedded within a polydimethylsiloxane (SrF2:Eu@PDMS). The SrF2:Eu demonstrates time-lapse imaging, reversible radio-photoluminescence, and recoverable X-ray storage, offering a promising avenue for optical information encryption and anticounterfeiting applications.

X-ray storage tracks characteristics for Ag-doped phosphate glass based on radio-photoluminescence

Ag-doped phosphate glass (Ag-PG) is an excellent X-ray image storage material applied for recording X-ray tracks. In this work, we used Geant4 software to simulate the energy deposition attenuation and 2D/3D storage tracks characteristics of Ag-PG. The influence of the secondary particles generated by the interaction between X-rays and Ag-PG was analyzed. The storage cutoff depth of Ag-PG was verified at the Shanghai Synchrotron Radiation Facility (SSRF). The results show that the optical transmittance is slightly decreased after X-ray irradiation. The cutoff depth is only 200 μm for complete absorption, when the X-ray energy is 5 keV. The deposited energy is attenuated by 19.8% at the depth of 900 μm, when the X-ray energy is 30 keV. The distribution of deposited energy is primarily influenced by the attenuation of secondary electrons generated by the interaction between X-rays and Ag-PG. Furthermore, the 2D/3D models show that the storage depth is not significantly affected by different doses at the same X-ray energy. The low diffusion of the tracks spread plays a crucial role in achieving high spatial resolution. The storage cutoff depth in Ag-PG is approximately 10 mm at 20 keV. This has been successfully verified by SSRF, and it holds great significance for high-resolution imaging and quantitative storage of X-ray images in Ag-PG.

The Effect of 147 MeV 84Kr and 24.5 MeV 14N Ions Irradiation on the Optical Absorption, Luminescence, Raman Spectra and Surface of BaFBr Crystals

Today, BaFBr crystals activated by europium ions are used as detectors that store absorbed energy in metastable centers. In these materials, the image created by X-ray irradiation remains stable in the dark for long periods at room temperature. As a result, memory image plates are created, and they are extended to other types of ionizing radiation as well. Despite significant progress towards X-ray storage and readout of information, the mechanisms of these processes have not been fully identified to date, which has hindered the efficiency of this class of phosphors. In this study, using photoluminescence (PL), optical absorption (OA), Raman spectroscopy (RS), and atomic force microscopy (AFM), the luminescence of oxygen vacancy defects to BaFBr crystals irradiated with 147 MeV 84Kr and 24.5 MeV 14N ions at 300 K to fluences (1010–1014) ion/cm2 was investigated. BaFBr crystals were grown by the Shteber method on a special device. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed the presence of Ba, Br, F, and O. The effect of oxygen impurities present in the studied crystals was considered. The analysis of the complex PL band, depending on the fluence and type of ions, showed the formation of three types of oxygen vacancy defects. Macrodefects (tracks) and aggregates significantly influence the luminescence of oxygen vacancy defects. The creation of hillocks and tracks in BaFBr crystals irradiated with 147 MeV 84Kr ions is shown for the first time. Raman spectra analysis confirmed that BaFBr crystals were amorphized by 147 MeV 84Kr ions due to track overlap, in contrast to samples irradiated with 24.5 MeV 14N ions. Raman and absorption spectra demonstrated the formation of hole and electron aggregate centers upon swift heavy ions irradiation.

Button-Type Beam Position Monitor Development for Fourth-Generation Synchrotron Light Sources: Numerical Modeling and Test Bench Measurements.

This paper addresses the design of beam position monitor (BPM) devices suitable for fourth-generation diffraction-limited X-ray storage rings. Detailed investigations of the electromagnetic (EM) phenomena occurring inside the component under various working conditions are carried out by considering different BPM EM models defined by their geometry and materials. Moving from a theoretical characterization of the common round geometry, rhomboidal structures are studied through a careful numerical analysis relying on advanced computer-aided tools. Several critical elements, such as wakefields, pick-up signal extraction, and trapped and propagating modes, are explored from the simulation point of view and from the experimental one, by deploying a manufactured microwave test bench, which is employed to measure the radio frequency behavior of a BPM prototype built at Elettra Sincrotrone Trieste. The aim of the proposed study is to identify a satisfactory tradeoff between achievable performance and practical realizability for BPM devices operating in last-generation light sources.

Inorganic metal oxide material BaSiO3:Eu2+ for convenient 3D X-ray imaging

X-ray storage phosphors are found wide-ranging applications in medical diagnosis, nondestructive testing and X-ray imaging. However, designing X-ray storage phosphors with high electron storage capacity still poses a daunting challenge. In this study, we designed a fluorescent powder based on Eu2+-doped BaSiO3, demonstrating excellent optical information storage characteristic. Under high-energy X-ray filling, shallow traps exhibit low electron capacity and only produce weak afterglow, which greatly helps to minimize the impact of afterglow on the image quality during X-ray imaging. In addition, the deep traps at 1.01 eV filled with high-energy X-ray allow the material to store information for a long time. The crystal structure, photoluminescence (PL) and thermoluminescence (TL) spectra were studied systematically. The electron trapping properties of the material were analyzed using TL spectroscopy. Finally, we fabricated a flexible film with phosphors, the flexible film has been utilized to demonstrate high-quality real-time X-ray imaging and achieve time-delayed X-ray imaging of curved objects, such as flexible circuit boards.

Charge carrier trapping management in Bi3+ and lanthanides doped Li(Sc,Lu)GeO4 for x-ray imaging, anti-counterfeiting, and force recording

Discovering energy storage materials with rationally controlled trapping and de-trapping of electrons and holes upon x-rays, UV-light, or mechanical force stimulation is challenging. Such materials enable promising applications in various fields, for instance in multimode anti-counterfeiting, x-ray imaging, and non-real-time force recording. In this work, photoluminescence spectroscopy, the refined chemical shift model, and thermoluminescence studies will be combined to establish the vacuum referred binding energy (VRBE) diagrams for the LiSc1−xLuxGeO4 family of compounds containing the energy level locations of Bi2+, Bi3+, and the lanthanides. The established VRBE diagrams are used to rationally develop Bi3+ and lanthanides doped LiSc1−xLuxGeO4 storage phosphors and to understand trapping and de-trapping processes of charge carriers with various physical excitation means. The thermoluminescence intensity of x-ray irradiated LiSc0.25Lu0.75GeO4:0.001Bi3+,0.001Eu3+ is about two times higher than that of the state-of-the-art x-ray storage phosphor BaFBr(I):Eu2+. Particularly, a force induced charge carrier storage phenomenon appears in Eu3+ co-doped LiSc1−xLuxGeO4. Proof-of-concept non-real-time force recording, anti-counterfeiting, and x-ray imaging applications will be demonstrated. This work not only deepens our understanding of the capturing and de-trapping processes of electrons and holes with various physical excitation sources, but can also trigger scientists to rationally discover new storage phosphors by exploiting the VRBEs of bismuth and lanthanide levels.

Luminescence characteristics and X-ray-induced defects in BaFBr:Eu2+ storage phosphor.

Three different approaches used to synthesize a sensitive BaFBr:Eu2+ X-ray storage photostimulated luminescence (PSL) phosphor at 850°C for 1 h in a reducing atmosphere are reported. The effects of F/Br and Eu concentration on photoluminescence (PL) and PSL sensitivities synthesized by the three approaches were compared. In the first recipe, BaFBr:Eu2+ prepared using a BaF2 , BaBr2 and EuF3 mixture using solid-state diffusion (Recipe I), even in a reducing atmosphere, yielded a low PL and PSL intensity due to oxygen contamination that acted as competing hole traps. When BaFBr:Eu2+ was prepared using ammonium bromide and ammonium fluoride by two different recipes (Recipes II and III), oxygen contamination was eliminated, resulting in enhanced PSL efficiency. The proposed PSL process in BaFBr:Eu2+ was consistent with the experimental results. Increased F/Br molar ratios would incorporate fluorine ion interstitials that act as hole traps accompanied by bromine ion vacancies that act as electron traps. Although two types of F centres, F(Br- ) and F(F- ) are possible, F(Br- ) centres formed during X-irradiation are only vital for the PSL process. Structural, morphology, and thermoluminescence (TL) properties of the samples were also examined using XRD, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDAX), and TL studies.

Energy-Trapping Management in X-Ray Storage Phosphors for Flexible 3D Imaging.

X-ray imaging has received sustained attention for healthcare diagnostics and nondestructive inspection. To develop photonic materials with tunable photophysical properties in principle accelerates radiation detection technologies. Here the rational design and synthesis of doped halide perovskite CsCdCl3 :Mn2+ , R4+ (R = Ti, Zr, Hf, and Sn) are reported as next generation X-ray storage phosphors, and the capability is greatly improved by trap management via Mn2+ site occupation manipulation and heterovalent substitution. Specially, CsCdCl3 :Mn2+ , Zr4+ displays zero-thermal-quenching (TQ) radioluminescence and anti-TQ X-ray-activated persistent luminescence even up to 448 K, further revealing the charge-carrier compensation and redeployment mechanisms. X-ray imaging with the resolution of 12.5 lp mm-1 is demonstrated, and convenient 3D X-ray imaging for the curved objects is realized in a time-lapse manner. This work demonstrates efficient modulation of energy traps to achieve high storage capacities and promote future research into flexible X-ray detectors.

Cellular and Biochemical Effects of Combined X-Ray Radiation and Storage on Whole Blood.

BackgroundEvaluating the impact of ionizing radiation on stored blood is relevant since blood banks are major assets in emergency conditions such as radiation incident/attack. This study aimed to fill our knowledge gap of combined radiation and storage effects on blood.MethodsBlood collected from 16 anesthetized rats was anticoagulated, aliquoted into storage bags, and assigned to 8 groups using protocols combining storage (1-day vs 3-day 4oC) plus irradiation (75 Gy vs 0 Gy - control). Bags were positioned inside an X-ray irradiator (MultiRad-350). Complete blood count, differential white blood cell count, biochemistry, and hemostasis were analyzed (≥7 bags/group).ResultsNa+, bicarbonate, glucose, and pH significantly reduced, while K+, Cl−, and lactate increased by storage. Coagulation measures were not significantly altered after radiation. White blood cell count and most cell types were numerically reduced after radiation, but changes were statistically significant only for monocytes. No significant alterations were noted in aggregation or rotational thromboelastometry parameters between irradiated and control.ConclusionsEvaluating cellular/biochemical parameters aids in assessing stored blood adequacy after radiation. Data suggest that fresh or cold-stored blood can sustain up to 75 Gy without major critical parameter changes and may remain suitable for use in critically ill patients in military/civilian settings.

Knowledge and practices of recording and maintaining patients ‘dental records among private dental practitioners of Delhi, India

Proper recording and keeping dental records are an important part of any dental practice. It helps in improving patient care, has medico-legal importance and play significant role in human identification during mass disasters or criminal offences. Aim: To assess the knowledge and practices of recording and maintaining patients ‘records among private dental practitioners of Delhi, India. Methods: Data for this cross-sectional study was collected from 160 dentists of Delhi using a self-administered questionnaire. The face and content validity as well as reliability of questionnaire was tested before the final data collection. A single trained examiner collected all the necessary information via personal visits or google forms. Chi-square test was applied to check the statistically significant difference between the dichotomous independent variables with respect to study participants’ responses to the questionnaire. Results: The mean age of the study participants was 34.5 (SD 7.2) years.Digital method of recording patient’s data and x-ray storage was more prevalent than manual method among the study participants. Slightly more than 40% of the dentists were keeping patient’s records safe for a period of 6 to 10 years. Younger dentists with lesser years of practice were more explicit in recording and correcting patient records. Conclusion: Results of this study shows that private dental practitioners of Delhi are aware of medico-legal importance of dental records. Most of them were recording important findings and history of their patients. Dentists must be educated in two aspects namely correct method of recording and the ideal duration of storing their patients’ dental records.

The effect of annealing on optical transmittance and structure of ZLANI fluorozirconate glass thin films

We report the effect of thermal annealing on structure, composition, optical transmittance and thickness of a novel fluorozirconate glass (ZLANI) containing Zr, La, Al, Na and In fluorides. In this work, pulsed laser deposition was used to grow thin films of ZLANI, and thermal annealing at different temperatures was performed on the films. Annealing did not change the composition, but a clear structural evolution of the ZLANI glass was observed by transmission electron microscopy (TEM), showing that we can control microstructure independent of composition. An increase in transmittance after the film was subject to a 100 °C thermal anneal was ascribed to the removal of defects and structural relaxation in the amorphous state. Following an anneal of 200 °C, the transmittance decreases due to heterogeneous formation of crystalline nuclei and changes in the local bonding. After the final annealing at 300 °C, a wider-scale crystallization occurred, with some major crystal phases formed as Zr2F8(H2O)6 and ZrO2, which alters the shape of the transmittance curve. The crystalline content of the crystal phases that form in the annealed films was quantified using hollow cone dark field TEM imaging. The 100 °C or 200 °C annealing decreases the film thickness by inducing structural relaxation and densification of the amorphous films, while the thickness increase of the 300 °C annealed film resulted from the formed large crystals. These results provide insights for the design of multilayer nanocomposites with a ZLANI glass matrix, which have potential applications as up-/down-conversion luminescent materials and X-ray storage phosphors.

Vacuum-Referred Binding Energies of Bismuth and Lanthanide Levels in ARE(Si,Ge)O4 (A = Li, Na; RE = Y, Lu): Toward Designing Charge-Carrier-Trapping Processes for Energy Storage

Developing a feasible design principle for solid-state materials for persistent luminescence and storage phosphors with high charge carrier storage capacity remains a crucial challenge. Here we report a methodology for such rational design via vacuum referred binding energy (VRBE) diagram aided band structure engineering and crystal synthesis optimization. The ARE(Si,Ge)O4 (A = Li, Na; RE = Y, Lu) crystal system was selected as a model example. Low-temperature (10 K) photoluminescence excitation and emission spectra of bismuth- and lanthanide-doped ARE(Si,Ge)O4 system were first systematically studied, and the corresponding VRBE schemes were then established. Guided by these VRBE schemes, Bi3+ afterglow and storage phosphor properties were explored in NaLu1-xYxGeO4. By combining Bi3+ with Bi3+ itself or Eu3+, Bi3+ appears to act as a deep hole-trapping center, while Bi3+ and Eu3+ act as less-deep electron traps. Trap depth tunable afterglow and storage were realized in NaLu1-xYxGeO4:0.01Bi3+ and NaLu1-xYxGeO4:0.01Bi3+,0.001Eu3+ by adjusting x, leading to conduction band engineering. More than 28 h of persistent luminescence of Bi3+ was measurable in NaYGeO4:0.01Bi3+ due to electron release from Bi2+ and recombination with a hole at Bi4+. The charge carrier storage capacity in NaYGeO4:0.01Bi3+ was discovered to increase ∼7 times via optimizing synthesis condition at 1200 °C during 24 h. The thermoluminescence (TL) intensity of the optimized NaYGeO4:0.001Bi3+ and NaYGeO4:0.01Bi3+,0.001Eu3+ is ∼3, and ∼7 times higher than the TL of the state-of-the-art X-ray storage phosphor BaFBr(I):Eu. Proof-of-concept color tuning for anti-counterfeiting application was demonstrated by combining the discovered and optimized NaYGeO4:0.01Bi3+ afterglow phosphor with perovskite CsPbBr3 and CdSe quantum dots. Information storage application was demonstrated by UV-light- or X-ray-charged NaYGeO4:0.01Bi3+,0.001Eu3+ phosphor dispersed in a silicone gel imaging film. This work not only reports excellent storage phosphors but more importantly provides a design principle that can initiate more exploration of afterglow and storage phosphors in a designed way through combining VRBE-scheme-guided band structure engineering and crystal synthesis optimization.

A sensitive x-ray storage phosphor based on BaFBr:Eu2+, KF/LiF with higher storage stability

A sensitive x-ray storage phosphor based on fluorine excess BaFBr:Eu2+,KF/LiF possessing high storage stability has been synthesized. The electron-hole recombination process giving rise to photostimulated luminescence (PSL) is described. No red shift in the stimulation spectra on alkali co-doping and thus no electron trapping at the Br− vacancies beside the alkali compounds were observed. The enhanced photoluminescence (PL) and PSL efficiencies could very well be explained by the synergistic flux action of the co-dopant(s) and BaBr2 at 850 °C which increases the crystallinity and doping efficiency. Sintering temperatures >900 °C enhanced the luminescence efficiencies of BaFBr:Eu2+ and BaFBr:Eu2+,KBr due to thermal migration of Fi− ions.

Efficient Generation of Stable Sm2+ in Nanocrystalline BaLiF3:Sm3+ by UV- and X-Irradiation

In recent decades, storage phosphors have found widespread applications in the fields of dosimetry and computed radiography due to their impressive properties including large dynamic range and passive storage mode. Despite this success, further development of highly efficient X-ray and UV sensitive luminescent materials is still desirable, in par-ticular for applications in dosimetry. In this Article we report X-ray and UV storage properties of nanocrystalline Ba-LiF3 doped with Sm3+. Nanocrystalline BaLiF3:Sm3+ was prepared mechanochemically by ball milling and the resulting product was characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The re-sponse of the phosphor to X-ray and UV radiation was investigated by measuring room temperature photolumines-cence spectra before and after irradiation for a wide range of doses. The lifetime of the Sm2+ emission at 694 nm was determined for both the X-ray and UV irradiated powder samples. The results indicate a potential fo...

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Synthesis, spectroscopic properties and applications of divalent lanthanides apart from Eu2+

Abstract In this review, modern insights into the synthesis and fundamental optical properties as well as applications of divalent lanthanides as spectral energy converters are discussed, which have especially evolved within the last two decades. An emphasis is put on the state-of-the-art knowledge about the luminescence of other divalent lanthanides than the most commonly applied representative Eu2+ and what special features in their luminescence arises due to the different number of 4fn electrons. In particular, the luminescence of Sm2+, Tm2+, Yb2+ and the less stable ions Nd2+ and Dy2+ will be regarded. A broad overview over the synthetic approaches to inorganic compounds based on divalent lanthanide ions will be conveyed as well and shall demonstrate the fascinating developments in the field of inorganic solid-state chemistry of the lanthanides. Besides their fundamental optical properties, also applications of the presented divalent lanthanide activators are discussed. Sm2+ is a well-known temperature and pressure sensor due to its interconvertible 4f‐4f and 5d-4f transitions. Moreover, nanocrystalline BaFCl:Sm2+ has an appreciable potential as novel X-ray storage phosphor. Tm2+ is interesting for upconversion in photovoltaic and lasing applications, whereas Yb2+ in halides may be a promising alternative to Eu2+ for scintillation materials and phosphors for light-emitting diodes (LEDs). Nd2+ and Dy2+ are currently emerging as novel near infrared (NIR)-absorbing and emitting activators that might become interesting as lasing ions. The spectroscopy of these unusual lanthanide ions provides many non-trivial features due to the excited two-open shell 4fn-15d1 configuration overlapping with the excited 4fn levels. Finally, a perspective for future developments will be given.

Photostimulated and persistent luminescence of samarium ions in BaFCl

Storage phosphors with efficient photostimulated luminescence (PSL) and/or persistent luminescence (PersL) are in great demand for a range of applications. In this paper, PSL, PersL and thermoluminescence (TL) of samarium ions doped in a macroscopic and sub-micron crystals of BaFCl are reported, and it is demonstrated that the co-precipitated BaFCl:Sm3+ sub-micron crystals become an efficient photostimulable X-ray storage phosphor upon annealing in the temperature range of 200–500 °C. The dependence of storage phosphor properties on annealing temperature was investigated and it was found that the X-irradiated co-precipitated BaFCl:Sm3+ crystallites (~400 nm size) showed maximum PSL and PersL from both Sm2+ and Sm3+ ions when annealed at 500 °C for 4 h. From a comparison with data for the macroscopic crystal (~3 mm) and ball-milled nanopowders (~30 nm), it also followed that PSL and PersL in the BaFCl:Sm system is affected by the crystal size. TL from Sm2+ of the macroscopic crystal is compared with the TL of sub-micron powders annealed at different temperatures.

Mechanochemical preparation of nanocrystalline metal halide phosphors

In recent years, mechanochemistry has experienced a massive resurgence allowing for solvent-free preparation of many important materials with minimal energy requirements. This paper provides a review of the mechanochemical preparation of nanocrystalline metal halides for applications as inorganic phosphor materials. The review puts strong emphasis on our recent work on optical and X-ray storage phosphors such as the matlockite BaFCl:Sm3+. In addition, previously unpublished results are presented including the effect on the samarium oxidation state when using ball-milling, as well as results on other rare earth-doped matlockites. We outline how mechanochemical methods can be applied to synthesise, without the need for solvents and high temperatures, a wide range of halides ranging from the most important commercial X-ray storage phosphor BaFBr:Eu2+ to lead perovskites of the formula APbX3 with A = Cs+, CH3NH3+, etc., and X = F, Cl, Br, I or a mixture thereof. We also demonstrate that a wide variety of solid solutions of the general formula $$ {\text{M}}_{x}^{1} {\text{M}}_{1 - x}^{2} {\text{FX}}_{y}^{1} {\text{X}}_{1 - y}^{2} $$ (with M1 and M2 = Ba, Sr, Ca; X1, X2 = Cl, Br, I) that can be suitable hosts for luminescent activator ions, can be prepared by mechanochemical methods. Importantly, for prolonged grinding times with a high-energy ball-mill, crystallites on the nanoscale can be obtained as can be confirmed by Rietveld refinements of powder XRD patterns and electron microscopy.

Nature of Localized Excitons in CsMgX3 ( X=Cl , Br, I) and Their Interactions with Eu2+ Ions

To advance high-energy detectors, we need a deeper understanding of the exciton-activator interaction in systems such as x-ray storage phosphors and scintillators. This article revisits the general molecular interpretation of self-trapped excitons known from binary alkali halides, and justifies extending this interpretation to the ternary quasi-one-dimensional halides CsMg${X}_{3}$. Direct evidence of interaction between polaronic self-trapped excitons and local luminescent Eu${}^{2+}$ activators is found. These results highlight the family of inorganic halide perovskites as interesting scintillators for tomorrow's detectors, in addition to solar-cell applications.