E-beam Irradiation Research Articles

In-situ atomic-scale observation the escape of irradiation-induced dislocation loops in magnesium

The formation of dislocations or dislocation loops in irradiated materials significantly alters the physical and mechanical properties of the materials. In this research, by applying in situ high-resolution transmission electron microscopy techniques, the dynamics of dislocation and self-interstitial atom (SIA) loops in magnesium (Mg) under electron beam (e-beam) irradiation at the atomic scale were observed directly. The structural characteristics of dislocation and dislocation loops were investigated with transmission electron microscopy. The in situ atomic-scale observation demonstrated that the edged dislocation gradually grew along the [1¯100] direction, while the SIA loop shrank along the same direction and eventually disappeared. The proposed processes resulted from the climbing of the dislocation and dislocation loops, which was related to the e-beam-induced anisotropic diffusion of the Mg atoms in the vicinity of the dislocations or dislocation loops. Significantly, only one side of the SIA loop near the thinner area was observed to shrink during the whole escape process, namely, a pinning phenomenon. The relevant mechanisms are discussed. The results present the detailed escape process of SIA dislocation loops at unprecedented resolution, and these results provide a significant insight into the advancement of irradiation resistance of materials.

Fabrication of Alq3/PMMA nanocomposite sheet and its potential applications as radiation dosimeter

Tris (8-hydroxyquinoline) aluminum (Alq3) is a highly luminescent organometallic compound, and therefore has numerous applications in electronic devices. Its unique optical property is suitable for organic light-emitting diodes, optoelectronic, and photodiodes. Despite its numerous potentials, no study investigated its response to ionizing radiation, particularly in its nanostructure form. In this work Alq3 were incorporated in a highly transparent polymethyl methacrylate (PMMA) polymer sheet using chloroform as a proper solvent for both materials. The ratio of Alq3 to PMMA powders was fixed at 1:10. The resulting composite showed recrystallized fine nanoparticles of Alq3, uniformly embedded in the PMMA sheet. Then small pieces of this nanocomposite sheet were exposed to various doses of X-ray and electron beam (E-beam) radiation doses in the range of 5–20 Gy. The molecular fingerprint and optical emission properties of the pristine and irradiated nanocomposite sheets were evaluated using Raman and PL spectroscopy. A systematic increase in the PL and Raman signals with increasing radiation doses were recorded. In addition, blueshift in the PL peak positions of nearly 6 and 9 nm for X-ray and E-beam irradiated sheets, respectively were also observed. These increments were attributed to the formation of radiative vacancies in the Alq3 molecules while the blueshift might be related to possible weakening of some of the Alq3 bonds such as C-O, C-C, C-H and Al-O, respectively. Therefore, the systematic changes in the optical properties might serve as preliminary parameters to investigate its potential use in radiation dosimetry following its nearly excellent linear dose dependence on signal intensities, which are quite encouraging.

Development of Novel Superabsorbent Hybrid Hydrogels by E-Beam Crosslinking.

In this study, several superabsorbent hybrid hydrogel compositions prepared from xanthan gum (XG)/sodium carboxymethylcellulose (CMC)/graphene oxide (GO) were synthesized by e-beam radiation crosslinking. We studied and evaluated the effects of GO content from the chemical structure of the hydrogels according to: sol-gel analysis, swelling degree, diffusion of water, ATR-FTIR spectroscopy, network structure, and dynamic mechanical analysis. The gel fraction and swelling properties of the prepared hydrogels depended on the polymer compositions and the absorbed dose. The hybrid XGCMCGO hydrogels showed superabsorbent capacity and reached equilibrium in less than 6 h. In particular, the XGCMCGO (70:30) hydrogel reached the highest swelling degree of about 6000%, at an irradiation dose of 15 kGy. The magnitude of the elastic (G′) and viscous (G″) moduli were strongly dependent on the absorbed dose. When the degree of crosslinking was higher, the G′ parameter was found to exceed 1000 Pa. In the case of the XGCMCGO (80:20) hydrogel compositions, the Mc and ξ parameters decreased with the absorbed dose, while crosslinking density increased, which demonstrated that we obtained a superabsorbent hydrogel with a permanent structure.

Critical media attributes in E-beam sterilization of corneal tissue

When ionizing irradiation interacts with a media, it can form reactive species that can react with the constituents of the system, leading to eradication of bioburden and sterilization of the tissue. Understanding the media's properties such as polarity is important to control and direct those reactive species to perform desired reactions. Using ethanol as a polarity modifier of water, we herein generated a series of media with varying relative polarities for electron beam (E-beam) irradiation of cornea at 25 kGy and studied how the irradiation media's polarity impacts properties of the cornea. After irradiation of corneal tissues, mechanical (tensile strength and modulus, elongation at break, and compression modulus), chemical, optical, structural, degradation, and biological properties of the corneal tissues were evaluated. Our study showed that irradiation in lower relative polarity media improved structural properties of the tissues yet reduced optical transmission; higher relative polarity reduced structural and optical properties of the cornea; and intermediate relative polarity (ethanol concentrations = 20-30% (v/v)) improved the structural properties, without compromising optical characteristics. Regardless of media polarity, irradiation did not negatively impact the biocompatibility of the corneal tissue. Our data shows that the absorbed ethanol can be flushed from the irradiated cornea to levels that are nontoxic to corneal and retinal cells. These findings suggest that the relative polarity of the irradiation media can be tuned to generate sterilized tissues, including corneal grafts, with engineered properties that are required for specific biomedical applications. Statement of significanceExtending the shelf-life of corneal tissue can improve general accessibility of cornea grafts for transplantation. Irradiation of donor corneas with E-beam is an emerging technology to sterilize the corneal tissues and enable their long-term storage at room temperature. Despite recent applications in clinical medicine, little is known about the effect of irradiation and preservation media's characteristics, such as polarity on the properties of irradiated corneas. Here, we have showed that the polarity of the media can be a valuable tool to change and control the properties of the irradiated tissue for transplantation.

Development of highly durable superhydrophobic and UV-resistant wood by E-beam radiation curing

Developing a practical strategy to fabricate an anti-abrasion and durable superhydrophobic wood surface with ultraviolet (UV) resistance has great practical significance for expanding the application of natural wood. In this study, a robust superhydrophobic layer with a hierarchical micro/nano-roughness structure was modified on the wood surface through in-situ mineralization and polymerization using a simple sol–gel method along with efficient electron beam (EB) curing technology. Hydrophobic agent (polydimethylsiloxane, PDMS), and crosslinking monomer (γ-methacryloxypropyl trimethoxysilane, MAPS) form new covalent bonds between TiO2 particle layer and wood substrate after EB radiation, which endows robust superhydrophobicity and remarkable UV resistance on the wood surface. The as-prepared wood exhibited a water contact angle of approximately 165.7° and obvious repellency to many aqua-phase liquids (cola, strongly acidic, alkaline droplets etc.). Furthermore, the hierarchical micro/nano-protrusion structures remained unchanged and micro/nano particles aggregated tightly on the as-prepared wood surface under harsh external environments (sandpaper abrasion and, ultrasonic treatment), confirming the desirable anti-abrasion and mechanically durable performance of the superhydrophobic surface. After the 18-day UV accelerated weathering test, the TiO2 particle layer conspicuously retained the discoloration and maintained its exceptional repellency toward water. The biomimetic superhydrophobic wood with excellent mechanical durability and UV resistance reveals its potential application in the furniture and architecture fields.

Chemical Dopant‐Free Doping by Annealing and Electron Beam Irradiation on 2D Materials (Adv. Electron. Mater. 10/2021)

Field-Effect Transistor Chemical-free and clean doping methods for 2D semiconducting materials are developed by Min Sup Choi, Won Jong Yoo, and co-workers in article number 2100449. The p- and n-doping in 2D field-effect transistors are observed by annealing and e-beam irradiation, attributed to the absorption of oxygen molecules and charge trapping at the interfaces, respectively.

Understanding the Effect of Al Doping on the Electrochemical Performance Improvement of the LiMn2O4 Cathode Material.

It is well known that the electrochemical performance of spinel LiMn2O4 can be improved by Al doping. Herein, combining X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM) with in situ electron-beam (E-beam) irradiation techniques, the influence of Al doping on the structural evolution and stability improvement of the LiMn2O4 cathode material is revealed. It is revealed that an appropriate concentration of Al3+ ions could dope into the spinel structure to form a more stable LiAlxMn2-xO4 phase framework, which can effectively stabilize the surface and bulk structure by inhibiting the dissolution of Mn ions during cycling. The optimized LiAl0.05Mn1.95O4 sample exhibits a superior capacity retention ratio of 80% after 1000 cycles at 10 C (1 C = 148 mA h g-1) in the voltage range of 3.0-4.5 V, which possesses an initial discharge capacity of 90.3 mA h g-1. Compared with the undoped LiMn2O4 sample, the Al-doped sample also shows superior rate performance, especially the capacity recovery performance.

Structure of boehmite-derived γ-alumina and its transformation mechanism revealed by electron crystallography

γ-Alumina is a widely used material, while its precise crystal structure and transformation mechanism derived from boehmite have remained unclear in the literature for decades. In this work, quantitative electron microscopy has been applied to study the crystalline structure of γ-alumina and its transformation mechanism from boehmite. Based on Rietveld refinement of electron diffraction patterns, a new tetragonal structure model, with a space group of I41/amd (No. 141), was proposed for the γ-alumina phase, with Al cations on 4a, 8c, 8d and 16g sites and O anions on the 16h site, which could provide better fits than current models. During the boehmite to γ-alumina transformation induced by e-beam irradiation, when the boehmite layers were oriented along the edge-on direction, a shrinkage caused by dehydration was directly observed. Two kinds of boehmite to γ-alumina transformation mechanisms, namely collapse and reaction mechanisms, were elucidated crystallographically in detail with new insights through an intermediate structure, and the reaction mechanism was demonstrated to produce much reduced changes in dimensions and volume, compared with the collapse mechanism. The experimental observations supported the reaction mechanism, which occurred through partial occupation of the dehydrated space by diffusion in the initial stage of the transformation, without the formation of voids that only appeared after the initial stage. Filling tetrahedral interstices of the intermediate structure with Al cations in different ways yields tetragonal or cubic γ-alumina structures, and the tetragonal structure is energetically favorable because of smaller lattice distortions required, compared with the cubic structure. The crystallographic orientation relationships of γ-alumina with the parent boehmite phase deduced from the proposed mechanisms are consistent with the experimental observations.

Fabrication of ethylene-vinyl acetate copolymer/polyamide/modified sepiolite composite with improved physical properties via e-beam irradiation

The effects of silanized sepiolite (SP) and electron beam (e-beam) irradiation on the physico-mechanical properties of ethylene-vinyl acetate copolymer (EVA)/ternary polyamide (tPA) composites were studied. SP was silanized with vinyltriethoxysilane (VTES) to enhance the dispersion and compatibility of the inorganic filler into the EVA/tPA matrix. The crosslinking of EVA/tPA by e-beam irradiation was carried out ranging from 50 to 250 kGy. The prepared composite films were characterized for change in morphology, mechanical properties, crosslinking effect on crystallinity and swelling using various established analytical techniques. Experimental results indicated that tensile strength of irradiated composite EVA/tPA/m-SP5 (70/30/5) was 3 times higher than that of virgin composite film at an absorbed dose of 250 kGy. The storage modulus of EVA/tPA/m-SP5 (70/30/5) composite film was significantly increased with the increase of absorbed dose. However, melting and crystallization temperature of EVA/tPA composites slightly decreased with the increase of absorbed dose. Moreover, the modification of SP with VTES and irradiated composite films were subjected to oil swelling studies.

Reliable Fabrication of Graphene Nanostructure Based on e-Beam Irradiation of PMMA/Copper Composite Structure.

Graphene nanostructures are widely perceived as a promising material for fundamental components; their high-performance electronic properties offer the potential for the construction of graphene nanoelectronics. Numerous researchers have paid attention to the fabrication of graphene nanostructures, based on both top-down and bottom-up approaches. However, there are still some unavoidable challenges, such as smooth edges, uniform films without folds, and accurate dimension and location control. In this work, a direct writing method was reported for the in-situ preparation of a high-resolution graphene nanostructure of controllable size (the minimum feature size is about 15 nm), which combines the advantages of e-beam lithography and copper-catalyzed growth. By using the Fourier infrared absorption test, we found that the hydrogen and oxygen elements were disappearing due to knock-on displacement and the radiolysis effect. The graphene crystal is also formed via diffusion and the local heating effect between the e-beam and copper substrate, based on the Raman spectra test. This simple process for the in-situ synthesis of graphene nanostructures has many promising potential applications, including offering a way to make nanoelectrodes, NEMS cantilever resonant structures, nanophotonic devices and so on.

Electron‐beam irradiation effect on the microbiological, physicochemical, and sensory parameters of refrigerated raspberries

The aim of this work was to study the impact of electron-beam (e-beam) irradiation (0.5–2 kGy) on microbiological, physicochemical, and sensory quality of raspberries, over a storage period of 14 days at 4°C. Results showed that irradiation had a significant effect (p < .05) on the reduction of the microbial population, weight loss, and the firmness of raspberries by slightly affecting the pH, TA, and TSS during storage. This effect depends on the used dose. The brightness of irradiated raspberries increased significantly by e-beam doses. The panel preferred raspberries irradiated with 0.5 and 1 kGy. In fact, untreated and treated at 2 kGy samples, showed a sensory degradation of stored raspberries. These results pointed out that e-beam irradiation can be considered as an environmentally friendly postharvest treatment suitable for conservation and preserving the quality of raspberries during storage. Novelty impact statement There is an ever-increasing consumer demand for food obtained by low-processed, more environmentally friendly, and greener preservation techniques to ensure food safety, guarantee high nutritional and organoleptic quality. E-beam irradiation at 0.5 and 1 kGy improved the color and some quality characteristics of raspberries better than control. E-beam irradiation at low doses is a method that may be a substitute and could be used along with conventional methods, providing raspberries quality.

E-beam irradiation of strawberries: Investigation of microbiological, physicochemical, sensory acceptance properties and bioactive content

The effect of electron beam irradiation (1–3 kGy) was studied on the microbiological, physicochemical, sensory, and bioactive properties of strawberries during storage at 4 °C for 14 days. E-beam treatment reduced the population of fungi to non-detectable levels and the bacterial mesophilic population by 2 log CFU g−1. Sensory analysis highlighted the strawberries treated at 2 kGy with 7 days storage as the most appreciated. Principal Compounds Analysis between the different physicochemical parameters and sensory descriptors suggested that the attributes of the strawberries irradiated at 1 and 2 kGy were enhanced comparatively to the control. The bioactive content of strawberries was preserved or improved after irradiation and 7 days of storage. The results indicated that e-beam treatment at 2 kGy and refrigerated storage could guarantee the microbial safety and extend the shelf-life up to 7 days, while preserve and/or improve the physicochemical and sensory attributes of strawberries. Industrial relevanceStrawberries are sources of compounds with high bioactivity and health benefits, despite of being high perishable. The present work demonstrated that e-beam radiation could be used as an environmental friendly and safe post-harvest treatment of strawberries to preserve the bioactive properties in order to extend their shelf-life, thus ensuring their quality and safety, and consequently, increasing their commercial value.

Electron-beam irradiation delayed the postharvest senescence of kiwifruit during cold storage through regulating the reactive oxygen species metabolism

The purpose of this study was to investigate the effects of electron-beam (e-beam) irradiation (0, 0.3, 0.4, and 0.5 kGy) on fruit firmness, total soluble solids (TSS), and active oxygen metabolism related indexes of kiwifruit during postharvest storage at 0–1 °C for up to 90 d. Results showed that e-beam irradiation retarded decrease in firmness as well as increase in TSS content in kiwifruit. The water-soluble pectin (WSP) content and ethylene production of the fruit decreased effectively after triggered by e-beam treatment. In addition, e-beam irradiation was able to improve the activities of peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), thus reducing the superoxide anions (O2−·) production rate, hydrogen peroxide (H2O2) content, malondialdehyde (MDA) content, and Lipoxygenase (LOX) activity. In general, 0.5 kGy e-beam irradiation presented the optimal preservation effects as the active oxygen metabolism and membrane lipid oxidation were inhibited to the greatest extent. The results of this work suggested that the appropriate dose of e-beam irradiation is an effective method for slowing down the increase in reactive oxygen species, maintaining normal metabolic processes and reducing the loss of fruit quality in kiwifruit during cold storage.

Electron beam irradiation studies of ZnGa2O4:Mn2+ green phosphor

The surface composition and stability of ZnGa2O4:Mn2+ green phosphor were evaluated using Auger electron spectroscopy (AES) under electron beam irradiation in vacuum and oxygen (4.0 × 10−7 mbar). The surface chemistry was monitored while measuring the cathodoluminescence (CL) intensity. The Auger peak-to-peak heights (APPHs) of Zn and Ga were stable during irradiation in vacuum for a beam current of 1 μA, whereas the APPH of Ga initially slightly increased during irradiation in vacuum and oxygen for a beam current of 3 μA. This was accompanied with a slight initial decrease of C contamination. The APPH of O decreased during irradiation in vacuum for a beam current of 3 μA, whereas it slightly increased during irradiation in oxygen. In vacuum the CL intensity exhibited a slight initial decrease during irradiation, after which it recovered and stabilized, whereas in oxygen the CL intensity decreased initially and then stabilized. The profile of the CL spectra did not show noticeable changes as a result of irradiation. TL measurements showed that the ZnGa2O4:Mn2+ activated with UV or e-beam exhibited two broad peaks. The differences were attributed to the change in concentrations of Zn and O vacancies that could be caused by e-beam irradiation.

Experimental and simulation study of power performance improvement of GaN PIN betavoltaic cell

We have demonstrated the gallium nitride (GaN)-based betavoltaic (BV) cells with PN and PIN junction to investigate the relationship between the intrinsic GaN (i-GaN) layer and power performance of BV cells. A short-circuit current (ISC) and an open-circuit voltage (VOC) of the fabricated BV cells were evaluated by using an electron-beam (e-beam) irradiation. The cell with PIN junction exhibited an improved ISC and VOC compared to the cell with PN junction. This is because the additional 200 nm-thick i-GaN layer extends the depletion region of BV cell, resulting in improved charge collection. When a 17 kV e-beam irradiated into the fabricated GaN PIN BV cell, the device exhibited an ISC of 1.86 μA, a VOC of 2.23 V, a maximum output power (Pmax.out) of 2.74 μW, and a power conversion efficiency (PCE) of 4.5%, respectively. This PCE is the best value among GaN BV cell researches using 17 keV e-beam irradiation. To study a role of i-GaN layer in PIN BV cell, the technology computer-aided design (TCAD) simulator was implemented. The effect of layer thickness and native defects in GaN material on the power performance of BV cell was evaluated. The power performance of PIN BV cell was degraded by introducing native defects in layers due to an increase of recombination rate. The BV cell with 500 nm-thick i-GaN layer exhibited better power performance when the electrons with average energy of Ni-63 irradiated into device because the maximum absorption rate of electrons was well positioned in the depletion region. The experimental and simulated results showed that the introduction of i-GaN layer and the optimization of parameters such as thickness and crystalline quality were important to improve the power performance of BV cells.

Influence of radiation conditions on the wear behaviour of Vitamin E treated UHMWPE gliding components for total knee arthroplasty after extended artificial aging and simulated daily patient activities

The long term performance of total knee arthroplasty (TKA) with regards to the bearing materials is related to the aging behaviour of these materials. The use of highly crosslinked materials in hip arthroplasty improved the clinical outcome. Nevertheless, the outcome for these materials compared to conventional UHMWPE (ultra-high molecular weight polyethylene) remains controversial in TKA and alternative bearing materials may be advantageous to improve its outcome in the second and third decade.The aim of this study is the evaluation of the influence of radiation conditions on the wear behaviour of Vitamin E blended UHMWPE gliding components for TKA by simulation of extended aging and high demanding daily patient activities. For a medium radiation dose (30 kGy), the influence of the irradiation type (E-beam or Gamma radiation) and the thermal conditions (room temperature (RT) or heated to 115 °C) are evaluated in comparison to non-irradiated material.Significant influences on the wear behaviour were found for the radiation source and temperature during irradiation. Furthermore, no relevant degradation of the tested materials was observed after extended artificial aging. There was a good correspondence between the wear pattern in this study and retrievals.

Self-feeding formation of atomically thin molybdenum nanoflakes on MoS2 monolayer

The decoration of atomically thin metal flakes on two-dimensional (2D) material membranes to impart intriguing properties for applications such as sensors and catalysis has attracted tremendous interest. Here, we report the formation of atomically thin Mo nanoflakes on a molybdenum disulfide monolayer (ML-MoS2) via a ‘self-feeding’ process using in situ transmission electron microscopy. Driven by energetic e-beam irradiation and thermal excitation, metallic Mo atoms preferentially segregate out and aggregate around mirror twin boundaries in the host MoS2 ML, which then assemble into metallic nanoflakes: the associated dynamic process captured at the atomic scale. The Mo atoms constituting the nanoflakes tend to sit on the Mo-top and S-top sites if they are viewed as absorbed atoms with respect to the ML-MoS2 substrate, which is further confirmed by theoretical calculations. Density functional theory calculations reveal that the entire system, i.e. metallic Mo nanoflakes sitting on the ML-MoS2 structure, exhibits overall metallic behavior, thus offering an efficient way to tune the electronic properties of the host MoS2. Such controlled fabrication can also enrich the 2D material family and provide new opportunities for exploiting their applications in catalytic and sensing devices.

Mixing nanostructured Ni/piezoPVDF composite thin films with e-beam irradiation: A beneficial synergy to piezoelectric response

Piezoelectric PVDF polymer thin films are nanostructured by swift heavy ion beam resulting in nanoporous structures. The nanocylindars are then partially filled with Ni(0) in order to create a composite of higher dielectric permittivity. In a second step, the composite is irradiated with electron beam, in order to induce chain scissions in the PVDF matrix and render it more flexible. It is found that e-beam irradiation does not affect the remanent polarization up to more than 1MGy. The energy harvesting properties are optimized with a maximum for 1MGy irradiation, delivering an output voltage of 4.1 V.cm−2 which corresponds to a maximum output power of 25μW. cm-2 and an integrated power of 0.46μW. cm−2 for 1 bar of external pressure (mechanical solicitations frequency of 10 Hz). The mechanisms responsible for the enhancement of the harvesting efficiency due to e-beam irradiation are discussed.

Radiolytic degradation of BDE-209 in rice-vegetable rotation soils induced by electron beam irradiation

Deca-brominated diphenyl ether (BDE-209) is shown to be persistent in soil and it's urgent to find an effective method to remove BDE-209 from contaminated soil. In this study, the investigation of BDE-209 degradation in three different rice-vegetable rotation soils induced by electron beam (E-beam) irradiation under flooded and non-flooded conditions was conducted. The reductive efficiency of 14C-BDE209 reached the highest level at 50 kGy and the values in flooded soils of rice-eggplant rotation soil (RES), rice-peanut soil (RPS), and rice-chili pepper soil (RCS) were 93.5%, 87.2%, and 73.8%, respectively. The reductive efficiencies in non-flooded soils of RES, RPS, and RCS were 73.4%, 81.0%, and 78%, respectively. The D0.5 values (dose required for reducing 50% BDE-209) of BDE-209 in non-flooded soils were lower than those in flooded soils, suggesting greater degradation efficiency of BDE-209 in non-flooded soils than in flooded soils. The BDE-209 was degraded into higher-brominated PBDEs and lower-brominated PBDEs by E-beam irradiation. The results demonstrate that BDE-209 in the soil can be degraded by E-beam irradiation, non-flooded condition is better than flooded condition for the removal of BDE-209, and the main degradation mechanism of BDE-209 by E-beam irradiation is debromination. This study provides a rapid and effective method for degrading BDE-209 that is persistent in soils, and has important implications for the remediation of soil contaminated by PBDEs in and around E-waste dismantling areas.

Second harmonic generation in periodically poled MgO:LN crystal with 2 µm period created by e-beam irradiation

The periodical domain structure with period 2 μm was created in 1-mm-thick MgO doped lithium niobate single crystals by electron-beam irradiation. The second harmonic generation (SHG) around 370 nm was obtained during pumping the crystals by 100 mW continuous wave tunable Ti:Sapphire laser. The normalized efficiency was 0.05%/W. The dependence of the SHG power on the pump beam position has indicated that the periodical domain structure depth is about 300 μm. The obtained results have demonstrated that the electron-beam poling can be used for creation of the short pitch periodical domain structures for light frequency conversion.