In situ electron beam irradiated rapid growth of bismuth nanoparticles in bismuth-based glass dielectrics at room temperature

In this study, in situ control growth of bismuth nanoparticles (Bi⁰ NPs) was demonstrated in bismuth-based glass dielectrics under an electron beam (EB) irradiation at room temperature. The effects of EB irradiation were investigated in situ using transmission electron microscopy (TEM), selected-area electron diffraction and high-resolution transmission electron microscopy. The EB irradiation for 2–8 min enhanced the construction of bismuth nanoparticles with a rhombohedral structure and diameter of 4–9 nm. The average particle size was found to increase with the irradiation time. Bismuth metal has a melting point of 271 °C and this low melting temperature makes easy the progress of energy induced structural changes during in situ TEM observations. This is a very useful technique in nano-patterning for integrated optics and other applications.     

Mechanisms of primary long-lived defect production in pure quartz glasses under electron irradiation

Based on an analysis of the dependences of individual absorption band amplitudes in quartz glasses on the electron beam (EB) fluence, mechanisms of primary defect production in KS-4V, KU-1, and Corning 7980 glasses during their prolonged irradiation by EB pulses are determined.     

Ionic conductivity study on electron beam irradiated polyacrylonitrileben polyethylene oxide gel

Different mass percent polyacrylonitrile (PAN)—polyethylene oxide (PEO) gels were prepared and irradiated by an electron beam (EB) with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity (IC) measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose (ID) and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN—PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN—PEO gels along with ID are divided into three regions: IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC—ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC—ID curve sharper, while addition of PEO in gel causes the curve milder.     

电子辐照改性PAN/PEO基体凝胶电解质对染料敏化太阳电池性能的提高

采用电子束（EB）对聚丙烯腈/聚氧化乙烯（PAN/PEO）凝胶电解质进行了剂量为13～260 kGy的辐照, 并对辐照改性的电解质组装的染料敏化太阳电池(DSSC)进行了性能测量。 结果表明, 改性后的DSSC的光电转化效率比改性前的高; 并且随EB辐照剂量的增加, DSSC效率先迅速增加(0～65 kGy), 然后缓慢减小(65～130 kGy)直至趋于一个平衡值(130～260 kGy)。 提升DSSC效率的最佳辐照剂量为65 kGy, 此时效率提高了约36%。 对比DSSC短路电流、 开路电压和填充因子随辐照剂量的变化, 发现DSSC效率的提高主要是由短路电流的提高引起的。 测量表明, 辐照改性后的DSSC时间稳定性得到了改善, 并且辐照剂量越高, 稳定性的改善越明显。 In this work, PAN/PEO (polyacrylonitrile/polyethylene oxide) based gel electrolyte was irradiated by electron beam (EB) with dose from 13 to 260 kGy. Then, DSSC (dye sensitized solar cell) was fabricated by the irradiated electrolyte and characterized. The results show that the efficiency of the DSSC fabricated by irradiated electrolyte is promoted comparing with DSSC fabricated by un irradiated electrolyte. And with irradiation dose increasing, the DSSC efficiency increases rapidly at first (0～65 kGy), then, drops down slowly (65～130 kGy), finally trends to a stable value (130～260 kGy). It indicates that there is an optimal irradiation dose, at which the promotion of DSSC efficiency is the highest, approximate 36%. Observed from the change of short circuit current, open circuit voltage and fill factor, short circuit current promotion by EB irradiation is found to be the main reason of DSSC performance promotion. The time stability measurement of the DSSC indicates that EB irradiation on PAN/PEO electrolyte reduces the loss of efficiency and the limiting effects become more apparent as the irradiation dose increases.     

Second-harmonic generation in Ge(20)As(25)S(55) glass irradiated by an electron beam

Second-harmonic generation was observed in Ge(20)As(25)S(55) chalcogenide glass irradiated by an electron beam. The second-harmonic intensity increased with increasing electron-beam current and accelerating voltage. The second-harmonic generation in Ge(20)As(25)S(55) glass was caused by the space-charge electrostatic field that was generated by irradiation of an electron beam. Second-order nonlinearity X((2)) as great as 0.8 pm/V was obtained. The results of measurements of thermally stimulated depolarization current indicated that the glass was poled in the thin layers of its surface (several micrometers) and that the nonlinearity was stable.     

Electron beam treatments of electrophoretic ceramic coatings

In this work a method to densify ceramic coating obtained by electrophoresis and to improve its adhesion to the substrate is proposed. It consists in irradiating the coating surface by electron beam (EB). Alumina and alumina-zirconia coatings were deposited on stainless steel substrates and treated by low power EB. SEM, XRD and TEM characterizations demonstrated that the sintering occurred. Moreover, it is shown that on alumina-zirconia coating the EB irradiation produced a composite material consisting principally of tetragonal zirconia particles immersed in an amorphous alumina matrix. The adhesion stress of EB treated coating was estimated by stud pull test and it was found to be comparable to that of plasma-sprayed coatings.     

Electron-induced interaction of condensed chlorine with Si(100)

We have studied electron-induced interaction of molecular chlorine with Si(100) surface under ultra-high vacuum conditions. Without electron beam irradiation, chlorine was found to be adsorbed both dissociatively (first step) and molecularly (second step) at 100 K. Illumination of molecular chlorine-covered surface at 100K with electron beam (1–3 keV) led to the formation of silicon tetrachloride on the Si(100) surface. We established that the surface reaction, that is responsible for the SiCl₄ formation, is initiated by Cl₂ dissociation and appearance of the active chlorine radicals. Importance of the such effect is also discussed in a view of their possible applications for selective etching of semiconductor surfaces.     

The Effects of Morphological Properties of Henequen Fiber Irradiated by EB on the Mechanical and Thermal Properties of Henequen Fiber/PP Composites

The aim of this study was to investigate the effects of electron beam (EB) irradiation on the morphological properties, crystallinity and surface area of henequen fiber and on the mechanical and thermal properties of henequen fiber reinforced polypropylene (PP) composites. The structure of henequen fiber was characterized by X-ray diffraction, mercury porosimetry and BET surface area analysis. The EB irradiation of 10 kGy led to the increasing of crystalline and surface pore area of henequen fiber, which contributed to the number of interlocking places with PP. From the results of tensile and impact strength tests, the highest value was observed for the composite reinforced with the henequen fiber treated with EB dose of 10 kGy, decreasing overall as EB dose increased. This tendency was also shown by coefficient of thermal expansion (CTE) measurements, but the value of CTE decreased until 50 kGy, meaning that a large total surface area can provide many interlocking places and so improve adhesion between fiber and matrix. Therefore, it can be concluded that the optimum pore surface area by 10 kGy irradiation contributes to successful mechanical interlocking between fiber and matrix and consequently enhances the mechanical and thermal properties of the composites.     

Internal structure transition of spin-on glass by electron beam irradiation

The effects of electron beam (EB) irradiation on spin-on glass (SOG) were investigated using thermal desorption spectroscopy. We were able to employ heat treatment as a “development process”, since we discovered that heat treatment breaks different bonds in SOG depending on whether it is applied before or after EB irradiation of SOG. In the case, when heat treatment was applied before EB irradiation of SOG, it was possible to break the Si-C bond at about 500 °C. In the case, when heat treatment was applied after EB irradiation of SOG, on the other hand, the -SiC bond could be broken at a lower temperature of about 400 °C. Using this difference between the two bond-breaking temperatures, it was possible to develop SOG using thermal desorption development (TDD). Moreover, the bond-breaking mechanisms revealed that the organic components in SOG play an important role in TDD. Hence, in order to determine the influence of organic components on TDD, the development characteristics of SOG samples with 10% and 15% organic contents were investigated.     

Impact of electron irradiation on particle track etching response in polyallyl diglycol carbonate (PADC)

In the present work, attempts have been made to investigate the modification in particle track etching response of polyallyl diglycol carbonate (PADC) due to impact of 2 MeV electrons. PADC samples pre-irradiated to 1, 10, 20, 40, 60, 80 and 100 Mrad doses of 2 MeV electrons were further exposed to 140 MeV²⁸ Si beam and dose-dependent track registration properties of PADC have been studied. Etch-rate values of the PADC irradiated to 100 Mrad dose electron was found to increase by nearly 4 times that of pristine PADC. The electron irradiation has promoted chain scissioning in PADC, thereby converting the polymer into an easily etchable polymer. Moreover, the etching response and the detection efficiency were found to improve by electron irradiation. Scanning electron microscopy of etched samples further revealed the surface damage in these irradiated PADCs.     

电子束辐照对聚碳硅烷结构与热解性能的影响

在惰性气氛下,用电子束对聚碳硅烷 (PCS) 进行辐照改性。利用傅里叶变换红外光谱分析、凝胶含量测定以及热重-气相色谱-质谱连用技术对不同剂量改性的PCS进行了分析表征,研究了辐照剂量对PCS结构与热解性能的影响。结果表明,电子束辐照作用使PCS样品中大量SiH键和CH键发生断裂,形成了以SiCSi为骨架的三维网状凝胶产物,当辐照剂量高于3 MGy时,PCS的凝胶化程度随辐照剂量的增加而明显变大。热重分析表明,电子束辐照有利于提高PCS的热稳定性,其初始失重温度和陶瓷化产率都会随辐照剂量的增加而升高,其中,经20 MGy辐照后的PCS样品的陶瓷化产率可达87%。此外,对于400 ℃预处理的PCS样品,在相同吸收剂量下,样品的凝胶质量分数、初始失重温度和最终陶瓷化产率都较未处理的高。     

Phase change of CoTi and Co3Ti induced by MeV-scale electron irradiation

This study investigates equilibrium-to-nonequilibrium solid phase transitions induced by MeV-scale electron irradiation in B2-CoTi and L1₂-Co₃Ti intermetallic compounds by means of high-voltage electron microscopy. Under MeV-scale electron irradiation, B2-CoTi transforms into a body-centered cubic solid solution through chemical disordering and eventually transforms into an amorphous phase. The critical temperature for amorphisation is found to be 110 K. L1₂-Co₃Ti also exhibits chemical disordering at temperatures below 700 K. However, its amorphisation does not occur even at a low temperature of 20 K. The dominant factor in these solid phase transitions is discussed in terms of the Gibbs free energy.     

Electron irradiation effects on 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole single crystal

In this paper, we report the electron irradiation effects on the properties of an organic NLO single crystal of 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole. The crystal was irradiated with electron beam of different doses and was characterized by powder XRD, UV-Vis, FTIR, DSC, microhardness and SHG measurements. In XRD, the peaks are shifted due to irradiation. The SHG efficiency has been found to enhance rapidly with irradiation. The investigation of the influence of electron irradiation on the surface morphology of the grown crystal reveals the formation of craters on the surface. The laser damage threshold remains constant as the dose rate increases whereas refractive index increases after irradiation.     

Kenaf/polypropylene biocomposites: effects of electron beam irradiation and alkali treatment on kenaf natural fibers

Thermal and dynamic mechanical properties of kenaf natural fiber reinforced polypropylene (PP) biocomposites were examined to compare the effects of natural fiber treatment by electron beam irradiation (EBI) and alkalization. The alpha cellulose contents, the functional groups on the surfaces and the thermal stability of the untreated and treated kenaf fibers were studied. Kenaf fiber/polypropylene(PP) biocomposites were fabricated by means of a compression molding technique using chopped kenaf fibers treated with electron beam (EB) dosages of 100, 200, 500 kGy or with NaOH concentrations of 2, 5, 10 wt%, respectively. The thermal stability, the dynamic mechanical and the interfacial properties of untreated and treated kenaf/PP biocomposites were also investigated through a thermogravimetric analysis, a dynamic mechanical analysis and a fractographic observation, respectively. The results show that the characteristics of kenaf fibers and biocomposites depended on the different treatment level with the EB dosages or on the NaOH concentrations used. In this study, the modification of kenaf fiber surfaces at 200 kGy EBI and treatment with 5 wt% NaOH was most effective for improving the performance of kenaf/PP biocomposites. This study suggests that EBI can be used for modification of natural fiber as an environmentally friendly process and contribute to an improvement in the performances of kenaf/PP biocomposites.     

Effect of high-energy electron beam irradiation on the surface morphology of CaF2/Si(100) heterostructures

The effect of high-energy electron beam irradiation on the surface morphology of CaF₂ films in the course of molecular-beam epitaxy on Si(100) substrates is studied by atomic-force microscopy. It is shown that not only do morphological defects significantly change their shape in the electron beam spot, but also their average height more than doubles.     

Imaging the phase separation in atomically thin buried SrTiO(3) layers by electron channeling

A phase-separation instability, resulting in the dewetting of thin SrTiO(3) films grown on Si(100) is shown by scanning transmission electron microscopy. Plan-view imaging of 1-nm thick, buried SrTiO(3) films was achieved by exploiting electron channeling through the substrate to focus the incident 0.2 nm beam down to a 0.04 nm diameter, revealing a nonuniform coverage by epitaxial SrTiO(3) islands and 2 x 1 Sr-covered regions. Density-functional calculations predict the ground state is a coexistence of 2 x 1 Sr-reconstructed Si and Sr-deficient SrTiO(3), in correspondence with the observed islanding.     

Self-organized amorphous material in silicon (0 0 1) by focused ion beam (FIB) system

A method using a focused ion beam (FIB) to prepare a silicon amorphous material is presented. The method involves the redeposition of sputtered material generated during the interaction of the Ga⁺ ion beam with a silicon substrate material. The shape and dimensions of this amorphous material are self-organized and reproducible. The stability of this amorphous material under electron irradiation was investigated in the transmission electron microscopy (TEM). Electron irradiation can induce recrystallization of the amorphous material, resulting in the lateral and vertical growth, starting at an amorphous-crystalline interface, of polysilicon containing defects.     

Observation of toroidal flow antiparallel to the <E(r) x B(straight theta)> drift direction in the hot electron mode plasmas in the compact helical system

A toroidal flow antiparallel to the drift direction is observed in the hot electron mode plasmas when a large positive electric field and a sharp electron temperature gradient are sustained inside the internal transport barrier in the Compact Helical System. This toroidal flow reaches up to 5x10(4) m/s at the plasma center, and it is large enough to reverse the toroidal flow driven by a tangentially injected neutral beam. These observations clearly show the plasma favors flow in the minimum nablaB direction at the transport barrier.     

Laser emission efficiency of semiconductor target of gas diode in the picosecond range

Laser radiation excited in a cadmiumsulfide semiconductor target (ST) (λ = 522 nm) by a high-intensity subnanosecond electron beam (EB) with an energy of 70–150 keV has a maximum intensity of 3 · 10⁷W/cm² at an efficiency of~10%. Lasing arose at the EB exciting pulse front. The laser radiation pulse shape reproduced the EB pulse shape.