Low-energy Photons Research Articles

Effect of lead oxide addition on gamma radiation shielding properties of newly developed geopolymers: theoretical and simulation studies

The efficiency of geopolymers as an effective immobilization system for various hazardous waste materials can be enhanced by adding PbO to improve its radiation shielding characteristics. In this study, the impact of PbO addition on the shielding properties of geopolymer composites was examined to evaluate the gamma radiation shielding characteristics of the geopolymer using FLUKA and XCOM computer programs. The results showed that adding 10% and 20% lead oxide significantly improved the shielding properties of the investigated geopolymer, mostly at lower photon energies. The higher values of MAC of 59.66728 cm2/g at 0.015 MeV, and 0.03916 cm2/g at 15 MeV for the investigated geopolymers suggest that these materials have improved radiation shielding at lower and intermediate energies due to higher photoelectric absorption and Compton scattering. The findings of this study provided valuable insights for designing high-performance radiation protection in medical imaging facilities, nuclear power plants, industrial radiography and other special radiation installations. Therefore, GEO doped with 20PbO should be deployed to fortify these facilities against ionizing radiations.

Study on Pressure-Induced Band Gap Modulation and Physical Properties of Direct Band Gap Ca3NX3 (X = Cl, Br) for Optoelectronic and Thermoelectric Applications

Utilizing density functional theory, we have comprehensively analyzed the structural, electronic, mechanical, transport, and thermodynamic properties of Ca3NCl3 and Ca3NBr3 photovoltaic materials. Furthermore, we investigated the impact of pressures ranging from 0 to 80 GPa and observed that the applied pressure decreases the atomic distances, resulting in significant changes in the physical properties of both materials. We employed GGA-PBE and TB-mBJ functionals to calculate the band structures and density of states, confirming their semiconducting nature. At 0 GPa, both compounds initially display a direct bandgap (Γ-Γ) of 1.5 eV for Ca3NCl3 and 1.26 eV for Ca3NBr3 based on GGA-PBE calculations. In contrast, the TB-mBJ calculations show an increase in the bandgap to 2.25 eV for Ca3NCl3 and 1.84 eV for Ca3NBr3, respectively. When a pressure of 80 GPa was applied, the direct bandgap of Ca3NCl3 and Ca3NBr3 decreased to 0.23 eV and 0.12 eV with GGA-PBE, and to 0.92 eV and 0.74 eV with TB-mBJ, respectively. It was also observed that the effective mass decreases under applied pressure, making these materials promising candidates for solar cell applications. The mechanical stability of both perovskites was maintained up to 80 GPa. Poisson's ratio and Pugh's ratio indicate that both compounds are brittle at 0 GPa but tend to become more ductile under applied stress. The optical properties reveal that pressure alters the dielectric function, absorption spectra, and optical conductivity, causing a red shift from higher to lower photon energies. Several thermodynamic properties, including heat capacity, Debye temperature, thermal expansion coefficient, and entropy, have been calculated, with their dependencies on temperature and pressure illustrated. Finally, the thermoelectric response of these materials is evaluated by examining how various transport parameters - such as the Seebeck coefficient, electrical and thermal conductivity, and power factor - depend on the temperature.

Design and performance analysis of novel perovskite/CZTSe hybrid solar cell for high efficiency

With newer developments, the solar cells in the market need to be more efficient, affordable, stable, and environment friendly. The perovskite solar cells have already shown very impressive progress in performance since their inception. It has already reached 26 % efficiency and is expected to reach more, owing to its stupendous photovoltaic nature. On the other hand, even with a very high absorption coefficient, the CZTSe solar cell has not crossed the 15 % efficiency mark. Looking at the characteristics of both the materials and considerable differences in band gap, a novel hybrid structure, HTL/Perovskite/CZTSe/CdS/ZnO, has been proposed in this work to implement Perovskite (CH3NH3Pb3−xClx) and CZTSe layer to absorb higher energy and lower energy photons respectively. In this context, choosing a proper Perovskite material becomes more crucial to have the required band alignment for the easy transportation of the excitons. The performance of the cell has been observed in varying parameters like thickness, doping, defects, and temperature. A high efficiency of 30.9 % is achieved which is much higher than the contemporary solar cells. Several other output parameters like Short Circuit Current Density (JSC), Open Circuit Voltage (VOC), Fill-Factor (FF%) characteristics have also been discussed.

Investigation of Gamma Ray Shielding Characteristics of Binary Composites Containing Polyester Resin and Lead Oxide

Ionizing radiation plays an essential role across various fields but also poses significant health risks, requiring effective shielding solutions. This study focuses on the photon shielding properties of PbO-reinforced composites, specifically PbO-0, PbO-2, PbO-4, PbO-6, PbO-8, and PbO-10, through experimental measurements of photon energies ranging from 59.5 keV to 1408.0 keV. The measurements were taken using an HPGe detector. Experimental results were compared to theoretical calculations. Among the tested composites, PbO-10, which contains the highest concentration of lead oxide (PbO), provided the most effective radiation shielding. This sample demonstrated superior mass and linear attenuation coefficients, offering excellent protection at low photon energies. Furthermore, PbO-10 exhibited the lowest half-value layer (HVL) and tenth-value layer (TVL) values, indicating its efficiency in reducing radiation intensity with thinner material layers. It was determined that the experimental TVL results for PbO-O, PbO-2, PbO-4, PbO-6, PbO-8, and PbO-10 at 59.5 keV photon energy were 9.95, 5.98, 4.77, 3.67, 3.22, and 2.71 cm, respectively. With these outstanding attenuation capabilities, PbO-10 is deemed highly suitable for use in medical, industrial, and radiation-heavy environments. In summary, this research emphasizes the effectiveness of PbO-reinforced composites in gamma-ray shielding, with PbO-10 emerging as the top performer, demonstrating great potential for applications that require durable and efficient radiation protection.

Single-Atom-Layer Metallization of Plasmonic Semiconductor Surface for Selectively Enhancing IR-Driven Photocatalytic Reduction of CO2 into CH4.

Efficient harvesting and utilization of abundant infrared (IR) photons from sunlight is crucial for the industrial application of photocatalytic CO2 reduction. Plasmonic semiconductors have significant potential in absorbing low-energy IR photons to generate energetic hot electrons. However, modulating these hot electrons to selectively enhance the activity of CO2 reduction into CH4 remains a challenge. Herein, the study proposes a single-atom-layer (SAL) metallization strategy to enhance the generation of IR-driven hot electrons and facilitate their transfer from plasmonic semiconductors to CO2 for producing CH4. This strategy is demonstrated using a paradigmatic W18O49@W-Sn nanowire array (NWA), where Sn2+ ions are grafted onto exposed O atoms on the surface of plasmonic W18O49 to form a surface W-Sn SAL. The incorporation of Sn single atoms enhances plasmonic absorption in IR light for W18O49 NWA. The W-Sn SAL not only promotes CO2 adsorption and reduces its reaction activation energy barrier but also shifts the endoergic CO-protonation process toward an exoergic reaction pathway. Thus, the W18O49@W-Sn NWA exhibits >98% selectivity for IR-driven CO2 reduction to CH4 with an activity over 9.0 times higher than that of bare W18O49 NWA. This SAL metallization strategy can also be applied to other plasmonic semiconductors for selectively enhancing CO2-to-CH4 reduction reactions.

Photon energy estimation in diagnostic radiology using OSL dosimeters: Experimental validation and Monte Carlo simulations

The EGSnrc Monte Carlo software toolkit was used to evaluate the energy response and estimate the photon energy based on the E3/E4 ratio for the InLight XA Optical Luminescence Dosimeters (OSLDs).The InLight XA OSLDs were irradiated with Cs-137 source and ISO 4037-1 narrow-spectrum series X-ray qualities (N40, N60, N80, and N100). The virtual OSLDs on the surface of the PMMA phantom were constructed in EGSnrc, energy response and ratio E3/E4 of the dosimeters was determined and compared to the physical measurements.Good agreement was found between the simulated and measurement approaches in estimating the photon energy with a percentage difference of less than 6%. The E3/E4 ratio from simulation, physical measurements, and microStar system showed very good agreement results with the maximum difference of 9.3% and 10.94%, respectively. Furthermore, the OSLDs energy response varied significantly at energy below 100 keV due to the photoelectric effect.The results of this study identify and address the over-response of OSLDs to low-energy photons, offering correction factors to minimize errors, especially in diagnostic radiology applications. These findings have the potential to improve dose accuracy for patients and radiation workers by providing more precise photon energy estimations, particularly at lower energy ranges, such as in diagnostic X-rays. The function used to evaluate photon energy using E3/E4 ratio has a great influence on the accuracy of such algorithms. It also ensures that imaging equipment is properly calibrated for the specific energy ranges needed, enhancing diagnostic accuracy. Furthermore, precise dose measurements are essential for maintaining regulatory compliance and long-term patient exposure records, ultimately promoting safer and more effective radiological practices.

Remarkable improvement in radiation shielding efficiency, thermal insulation performance and compressive strength of rigid polyurethane foam composites by synergetic effect of PbO and colemanite fillers

Developing radiation shielding materials is a critical phenomenon for protecting people and the environment with the increment in usage of nuclear technology in today's world. With this sense, PbO/colemanite-filled rigid polyurethane foams were fabricated by one-shut free rise method, and their performances were investigated via the advanced characterization techniques such as ATR-FTIR, SEM-EDS, TGA as well as thermal conductivity, universal mechanical and radiation shielding tests. The characteristic properties of the samples were evaluated in detail depending on the variation in the filler contents. The ATR-FTIR analysis illustrated that RPUF matrices exhibited good compatibility with the fillers by forming the secondary chemical bonds. Furthermore, SEM analysis revealed that the samples with low PbO/colemanite fillers exhibited fairly uniform and regular cellular morphology with anisotropic elliptical apparition thanks to synergetic catalytic effect of the filler particles, whereas, at high content, some local distortions with slightly chaotic appearance were observed accompanied by viewing the little ruptures and bursts in cell face and collapsed in cell plateau borders. TGA measurement indicated that the inclusion of the fillers into RPUF got worse the samples with comparison of neat RPUF due to the reduction in crosslinking density of the foam. Remarkable improvement (about 25 %) was also obtained in thermal insulation performance at the foam composites containing the fillers due to highly augmentation in number of closed cells and presence of more immobile CO2 gas inside the cells. Furthermore, high inclusion of the fillers in RPUF matrix improved compressive strength of the foams by nearly 15 % by enhancing the bending moment and rigidity of RPUF matrices via contributing to the overall stress dispersion. According to linear and mass attenuation coefficients results, the foam composites displayed excellent X-ray radiation shielding performance with increasing of PbO/colemanite content thanks to the density increment and presence of the atoms with high atomic number. Furthermore, at low photon energy levels, better shielding against X-ray radiation was obtained, while vice versa at high energy levels.

Room temperature single-photon terahertz detection with thermal Rydberg atoms

Single-photon terahertz (THz) detection is one of the most demanding technologies for a variety of fields and could lead to many breakthroughs. Although significant progress has been made in the past two decades, operating it at room temperature still remains a great challenge. Here, we demonstrate, for the first time, a room temperature THz detector at single-photon levels based on nonlinear wave mixing in thermal Rydberg atomic vapor. The low-energy THz photons are coherently upconverted to high-energy optical photons via a nondegenerate Rydberg state involved in a six-wave mixing process, and therefore, single-photon THz detection is achieved by a conventional optical single-photon counting module. The noise equivalent power of such a detector reaches 9.5 × 10−19 W/Hz1/2, which is more than four orders of magnitude lower than the state-of-the-art room temperature THz detectors. The optimum quantum efficiency of the whole-wave mixing process is about 4.3%, with 40.6 dB dynamic range, and the maximum conversion bandwidth is 172 MHz, which is all-optically controllable. The developed fast and continuous-wave single-photon THz detector at room temperature operation has a great potential for portability and chip-scale integration, and could be revolutionary for a wide range of applications in remote sensing, wireless communication, biomedical diagnostics, and quantum optics.

Investigation of the physical properties and pressure-induced band gap tuning of Sr3ZBr3 (Z=As, Sb) for optoelectronic and thermoelectric applications: A DFT - GGA and mBJ studies

This study discusses the feasibility of diversifying the scope of application of lead-free Sr3ZBr3 (Z = As, Sb) as promising materials for their enhanced electronic, mechanical, optical, thermodynamic, and thermoelectric properties using first-principles calculation based on Density Functional Theory (DFT). Both compounds have cubic crystal structures, and both materials' dynamic stability is validated by the lack of negative frequencies in their phonon dispersion spectra. Besides ground state physical characteristics, we also examined the impact of hydrostatic pressure (0–21 GPa) on electronic, mechanical, and optical properties. The lattice parameters exhibit a linear decrease from 6.27 to 5.61 Å for Sr3AsBr3 and 6.45 to 5.71 Å for Sr3SbBr3 under increasing pressure, attributed to bond length reduction, which alters their physical properties. Initially observed direct band gap (Γ-Γ) of Sr3AsBr3 and Sr3SbBr3 were 2.35 and 2.30 eV using modified Becke-Johnson (mBJ) functional which reduces to 1.15 and 0.82 eV as the compounds go from 0 to 21 GPa pressure. This study reveals enhanced optical properties under pressure, with broader spectral response, increased sensitivity, and improved dielectric constant. Optical absorption and conductivity also shift toward lower-energy photons. The investigation further shows that the compounds show brittle to ductile transition under high pressure. Their ductility and anisotropy nature are further enhanced with pressure along with other mechanical features. The thermodynamic properties indicate their ability to withstand and perform well at high temperatures and pressures. Lastly, the thermoelectric properties of Sr3ZBr3 (Z = As, Sb) were assessed through electrical and thermal conductivity, Seebeck coefficient, power factor (PF), and figure of merit (ZT) as a function of temperature. Both compounds exhibit high PF and near-unity ZT. These findings underscore their potential as strong candidates for optoelectronic and thermoelectric devices, owing to their direct bandgap and exceptional properties.

Ultra-Low Threshold Resonance Switching by Terahertz Field Enhancement-Induced Nanobridge.

Ongoing efforts spanning decades aim to enhance the efficiency of optical devices, highlighting the need for a pioneering approach in the development of next-generation components over a broad range of electromagnetic wave spectra. The nonlinear transport of photoexcited carriers in semiconductors at low photon energies is crucial to advancements in semiconductor technology, communication, sensing, and various other fields. In this study, ultra-low threshold resonance mode switching by strong nonlinear carrier transport beyond the semi-classical Boltzmann transport regime using terahertz (THz) electromagnetic waves are demonstrated, whose energy is thousands of times smaller than the bandgap. This is achieved by employing elaborately fabricated 3D tip structures at the nanoscale, and nonlinear effects are directly observed with the THz resonance mode switching. The nanotip structure intensively localizes the THz field and amplifies it by more than ten thousand times, leading to the first observation of carrier multiplication phenomena in these low-intensity THz fields. This experimental findings, confirmed by concrete calculations, shed light on the newly discovered nonlinear behavior of THz fields and their strong interactions with nanoscale structures, with potential implications and insights for advanced THz technologies beyond the quantum regime.

Multi-energy CT and iodinated contrast

Spectral CT acquires images with the emission or detection of two separate energy spectra. This enables material decomposition due to the photoelectric effect (prevalent in low-energy photons) and Compton scattering (prevalent in high-energy photons).Iodine and other materials with high atomic numbers appear more hyperdense on low-energy monoenergetic images because of the direct relation between the photoelectric effect and the Z value.Given the way iodine behaves on spectral maps, radiologists can optimise the use of contrast media in these CTs, thus allowing lower doses of radiation and lower volumes of contrast media while achieving the same CT values and even enabling lower contrast flow rates, which is especially helpful in patients with poor vascular access. Moreover, in suboptimal diagnostic cases caused by poor contrast opacification, the resolution can be improved, thus avoiding the need to repeat the study.

DFT based analysis of pressure driven mechanical, opto-electronic, and thermoelectric properties in lead-free InGeX3 (X = Cl, Br) perovskites for solar energy applications

Lead halide perovskites have distinct physiochemical properties and demonstrate remarkable power conversion efficiency. We used density functional theory to investigate the electrical, optical, structural, and elastic features of non-toxic InGeCl3 and InGeBr3 halide perovskite compounds at different hydrostatic pressures, from 0 to 8 GPa. InGeCl3 and InGeBr3 halide perovskite exhibit noteworthy changes in their electronic and optical properties under different pressure conditions. When the pressure is 0 GPa, the direct bandgap for InGeCl3 is 0.886 eV, and for InGeBr3 it is 0.536 eV. This gap decreases as the pressure rises. Specifically, InGeBr3 exhibits conducting properties at 3 GPa due to its larger bromine atoms, whereas InGeCl3 requires a higher pressure of 6 GPa to achieve similar conductivity. This type of nature suggests that larger halogen atoms reduce the bandgap more effectively under pressure. As the pressure increases, the behavior of the lattice constant and unit cell volume decreases constantly, from 5.257 and 145.267 Å3 for InGeCl3 to 5.509 and 167.168 Å3 for InGeBr3 at 0 GPa for both compounds. When subjected to pressure, the bonds between In-X and Ge-X atoms experience compression, leading to a decrease in surface area and an enhancement in mechanical strength. Overall, the compounds exhibit characteristics of semiconductors, as evidenced by evaluations of their electrical properties. As pressure increases, the bandgap decreases linearly, narrowing until it aligns with the Fermi level, leading to a transition toward a metallic state. In addition, the pressure induces a rise in the electrical density of states around the Fermi level by displacing valence band electrons in an upward direction. As pressure increases, the electron density peak shifts to lower photon energy values. Notably, InGeCl3 exhibits a more pronounced shift in this peak compared to InGeBr3, indicating greater sensitivity to pressure. In terms of optical properties, both compounds demonstrate significant absorption coefficients in the visible region, suggesting their potential suitability for photovoltaic applications. The dielectric constant, absorption, and reflectivity values all increase gradually as pressure increases. The absorption spectra shift toward longer wavelengths. Furthermore, the mechanical properties analysis reveals that all InGeX3 compounds are mechanically stable up to 8 GPa pressure.

Constraining the average magnetic field in galaxy clusters with current and upcoming CMB surveys

Galaxy clusters that host radio halos indicate the presence of population(s) of non-thermal electrons. These electrons can scatter low-energy photons of the Cosmic Microwave Background, resulting in the non-thermal Sunyaev-Zeldovich (ntSZ) effect. We measure the average ntSZ signal from 62 radio-halo hosting clusters using the Planck multi-frequency all-sky maps. We find no direct evidence of the ntSZ signal in the Planck data. Combining the upper limits on the non-thermal electron density with the average measured synchrotron power collected from the literature, we place lower limits on the average magnetic field strength in our sample. The lower limit on the volume-averaged magnetic field is 0.01–0.24 μG, depending on the assumed power-law distribution of electron energies. We further explore the potential improvement of these constraints from the upcoming Simons Observatory and Fred Young Submillimeter Telescope (FYST) of the CCAT-prime collaboration. We find that combining these two experiments, the constraints will improve by a factor oftwo, which can be sufficient to rule out some power-law models.

Eco-friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles for enhanced dye-sensitized solar cells utilizing oxalis Corniculata leaf extract

An environmentally friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles (NPs) was developed using Oxalis Corniculata leaf (OCL) extract to enhance the performance of dye-sensitized solar cells (DSSCs). The as-synthesized NPs were annealed at 600 °C to improve their crystallinity. X-ray diffraction and field-emission scanning electron microscopy revealed high crystallinity and a sub-100 nm spherical morphology. Annealing reduced the NP size from ∼85 nm to ∼45 nm and decreased the bandgap from 4.97 eV to 4.62 eV, enhancing low-energy photon absorption. Fourier-transform infrared spectroscopy showed changes in the chemical bonding environment, with a higher presence of dangling bonds in the as-prepared NPs compared to the 600 °C-annealed NPs, likely due to the OCL extract. Photoluminescence spectra confirmed strong red emission peaks at 580 nm and 612 nm, with a slight reduction in the full width at half maximum of the electric dipole transition after annealing. Integrating these NPs into TiO₂ matrices in DSSCs improved power conversion efficiency to 8.58%, outperforming both as-prepared NPs (6.88%) and bare TiO₂ cells (5.05%). This green synthesis approach offers a sustainable pathway for slightly enhancing performance of photovoltaic devices, with additional potential for UV-shielding applications when incorporated into PVA films.

Emerging New-Generation Semiconductor Single Crystals of Metal Halide Perovskites for Radiation Detection

Radiation detection uses semiconductor materials to convert high-energy photons into charge (direct detection) or low-energy photons (indirect detection), and it has a wide range of applications in nuclear physics, medical imaging, astronomical detection, homeland security, and other fields. Metal halide perovskites have the advantages of high frequency number, high carrier mobility, high defect tolerance, low defect density, adjustable band gap, and fast light response, and they have wide application prospects in the field of radiation detection. However, the research is still in its infancy stage, and it is far from meeting the requirements of industrial application. This paper focuses on the advantages of metal halide perovskite single-crystal materials in both semiconductors-based direct conversion detection and scintillator-based indirect detection as well as the latest progress in this promising field. This paper not only introduces the latest application of lead halide perovskite monocrystalline materials in high-energy electromagnetic radiation detection (X-ray and γ-rays), but it also introduces the latest development of α-particle/β-particle/neutron detection. Finally, this paper points out the challenges and future prospects of metal halide perovskite single-crystal materials in radiation detection.

Sustainable production of radionuclidically pure antimony-119

BackgroundRadiopharmaceutical therapy (RPT) uses radionuclides that decay via one of three therapeutically relevant decay modes (alpha, beta, and internal conversion (IC) / Auger electron (AE) emission) to deliver short range, highly damaging radiation inside of diseased cells, maintaining localized dose distribution and sparing healthy cells. Antimony-119 (119Sb, t1/2 = 38.19 h, EC = 100%) is one such IC/AE emitting radionuclide, previously limited to in silico computational investigation due to barriers in production, chemical separation, and chelation. A theranostic (therapeutic/diagnostic) pair can be formed with 119Sb’s radioisotopic imaging analogue 117Sb (t1/2 = 2.80 h, Eγ = 158.6 keV, Iγ = 85.9%, β+ = 262.4 keV, Iβ+ = 1.81%).ResultsWithin, we report techniques for sustainable and cost-effective production of pre-clinical quality and quantity, radionuclidically pure 119Sb and 117Sb, novel low energy photon measurement techniques for 119Sb activity determination, and physical yields for various tin target isotopic enrichments and thicknesses using (p, n) and (d, n) nuclear reactions. Additionally, we present a two-column separation providing a radioantimony yield of 73.1% ± 6.9% (N = 3) and tin separation factor of (6.8 ± 5.5) x 105 (N = 3). Apparent molar activity measurements for deuteron produced 117Sb using the chelator TREN-CAM were measured at 42.4 ± 25 MBq 117Sb/µmol (1.14 ± 0.68 mCi/µmol), and we recovered enriched 119Sn target material at a recycling efficiency of 80.2% ± 5.5% (N = 6) with losses of 11.6 mg ± 0.8 mg (N = 6) per production.ConclusionWe report significant steps in overcoming barriers in 119Sb production, chemical isolation and purification, enriched target material recycling, and chelation, helping promote accessibility and application of this promising therapeutic radionuclide. We describe a method for 119Sb activity measurement using its low energy gamma (23.87 keV), negating the need for attenuation correction. Finally, we report the largest yet-measured 119Sb production yields using proton and deuteron irradiation of natural and enriched targets and radioisotopic purity > 99.8% at end of purification.

Optimizing Upconversion Quantum Yield via Structural Tuning of Dipyrrolonaphthyridinedione Annihilators.

Triplet-triplet annihilation upconversion (TTA-UC) is a photophysical process in which two low-energy photons are converted into one higher-energy photon. This type of upconversion requires two species: a sensitizer that absorbs low-energy light and transfers its energy to an annihilator, which emits higher-energy light after TTA. In spite of the multitude of applications of TTA-UC, few families of annihilators have been explored. In this work, we show dipyrrolonaphthyridinediones (DPNDs) can act as annihilators in TTA-UC. We found that structural changes to DPND dramatically increase its upconversion quantum yield (UCQY). Our optimized DPND annihilator demonstrates a high maximum internal UCQY of 9.4 %, outperforming the UCQY of commonly used near-infrared-to-visible annihilator rubrene by almost double.

Enhancing low-energy X-ray excited afterglow in lanthanide-doped fluoride core@shell nanoparticles for autofluorescence-free imaging

Lanthanide-doped fluoride nanoparticles (NPs) exhibit tunable X-ray excited afterglow (XEA), holding great promise for autofluorescence-free flexible X-ray imaging. However, materials with low atomic numbers, while sensitive to low-energy X-ray photons, suffer from weak X-ray absorption coefficients. This poses a significant challenge in achieving high-performance XEA with minimized radiation risk. In this study, we enhance the low-energy XEA of lanthanide activators by engineering the interfacial defect formation energy (Ef) in CaF2-based heterogeneous core/shell nanoarchitectures. Mechanistic investigations demonstrate that a large lattice misfit between the core and shell reduces the interfacial defect Ef, facilitating the formation of Frenkel defects and significantly increasing XEA intensity after low-energy X-ray irradiation. Specifically, the heterogeneous CaF2:Tb@CaLuF5 core/shell NPs, with a misfit of 3.382 %, exhibit approximately ∼ 8.9 times higher XEA intensity compared to the CaF2:Tb@CaF2 homogeneous core/shell NPs at 10 kV. Furthermore, integrating the CaF2:Tb@CaLuF5 NPs into a flexible scintillation screen enables XEA-based delayed imaging with high spatial resolution, up to approximately 14.2 lp mm−1, and an autofluorescence-free background. These findings advance the development of superior low-energy XEA materials and pave the way for autofluorescence-free three-dimensional X-ray imaging.

Development of novel multifunctional phase change microcapsules for improving thermal comfort and radiation properties

Microencapsulated phase change materials (MPCMs) have gained widespread application in energy-efficient buildings, aiming to improve thermal comfort and reduce energy consumption. To enhance the engineering feasibility of MPCMs, researchers are now focusing on developing MPCMs with multifunctional properties, beyond single thermal storage functionality. In this study, we proposed a novel and straightforward approach to fabricate multifunctional MPCMs with BaCO3 as shell and a core composed of binary phase change materials (PCMs) and lipophilic-modified graphite (MG) via self-assembly method. The incorporation of BaCO3 shell provides MPCMs with additional resistance to ionizing radiation pollution due to the high atomic number element Ba. Additionally, the incorporation of MG into PCMs enhances its temperature sensitivity. The thermal analysis indicates that the binary PCMs’ composition in MPCMs results in two phase transition temperatures at 3.3 °C and 26.4 °C, making them capable of thermal storage in line with comfortable residential temperatures across different seasons. Furthermore, MPCMs were introduced into cement paste (CPM) and used to construct cement chambers. Adding 10 wt% MPCMs in the CPM chambers placed outdoors in Wuhan (from June 7th to June 9th) led to a 23.8 % decrease in temperature fluctuations compared to the reference sample. Radiation shielding results indicated that the linear attenuation coefficient (μ) of CPM increased by 58.7 %, due to enhanced incoherent scattering and photoelectric effects between high atomic number elements and photons. Additionally, XCOM simulations predicted a strong correlation between MPCM content and μ values, with particularly high accuracy at low photon energies. Overall, the multifunctional MPCMs developed in this study not only offers a new route for reducing residential energy consumption and shielding ionizing pollution, but also broadens the applicability of traditional PCMs in the building and other fields.

First principle study of structural and optoelectronic properties of ZnLiX3 (X = Cl or F) perovskites

The zinc-based perovskites ZnLiX3 (X = Cl or F) were investigated for their structural, electronic, and optical properties using the WIEN2k package within density functional theory (DFT). Structural properties were calculated using the generalized gradient approximation (GGA), while the modified Becke-Johnson (mBJ) potential was applied for a more accurate description of the optical and electronic properties. Both compounds are confirmed to be stable, crystallizing in the cubic Pm-3 m (No. 221) space group. ZnLiCl3 has an indirect band gap of 0.30 eV between the Γ and M symmetry points, indicating semiconducting behaviour, while ZnLiF3 exhibits an indirect band gap of 5.45 eV, typical of an insulating material. The electronic states contributing to the band structure were analyzed using the total density of states (TDOS) and partial density of states (PDOS). Optical properties, evaluated in the energy range of 0–14 eV, reveal strong optical conductivity and absorption at higher energies, while both materials show transparency to lower-energy photons. These findings suggest that ZnLiCl3 and ZnLiF3 are suitable candidates for high-frequency UV optoelectronic device applications.