Narrow Results

Fluorinated graphene was irradiated by electron beam, and the changing of fluorinated graphene after electron beam irradiation was found by several detection techniques of Raman, electrical characterization and X-ray photoelectron spectroscopy (XPS). Raman spectra and electric characterization confirmed that the crystal structure and electrical performance of graphene was recovered partially after electron beam irradiation. XPS results indicated that the concentration of fluorine quickly dropped from 35% to 15% just after 30 min irradiation, and then dropped, slowly to 10% with the irradiation time to 150 min. The results indicate that stimulate fluorine desorption from fluorinated graphene used electron beam completely is difficult, which means a big challenge for ESD to fabricate all graphene electronics.

An electron beam surface alloying was applied to a medium carbon steel disk using hBN, W and WC powders in order to examine the effect of these powder materials on the microstructure and hardness. The study reveals that, the surface hardness was improved by the electron beam irradiation with all powders and no surface cracks were observed due to the martensitic transformation and the surface alloying. However the influence of powder materials on the hardness was little. Thus, it was found the surface modification by the electron beam irradiation with various powders is effective way to improve the surface hardness as well as the prevention of surface cracking.

The measured current traces of two low energy machines namely the AECS PF-2 and INTI PF are used for studying of the produced electron beam features using the modified Lee code (RADPFV5.15REB) at different conditions. The fitting procedures between measured and computed current traces are made for each point of pressure. In the case of AECS PF-2 working with neon, the electron fluence reaches the maximum value $2.35\times 10^{22}$ electrons m${}^{-2}$ for 1.6 Torr and the flux achieves $2.42\times 10^{30}$ electrons m${}^{-2}$s${}^{-1}$ near 1.5 Torr. The electron number has a peak of $5.74\times 10^{14}$ at 0.9 Torr. The computed results demonstarte also the maximum value of the power flow density of $2.44\times 10^{16}$ Wm${}^{-2}$, and the superior damage factor of around $1.95\times 10^{12}$ Wm${}^{-2}$s${}^{0.5}$ at a pressure of 0.4 Torr. Argon presents the action of radiative cooling topping at highly magnified $6.13\times 10^{31}$ m${}^{-2}$s${}^{-1}$ at 0.9 Torr. The damage factor reaches almost $175\times 10^{12}$ Wm${}^{-2}$s${}^{0.5}$ for Ar but it is only $1.29\times 10^{12}$ Wm${}^{-2}$s${}^{0.5}$ for N₂. The huge values for argon are a result of enhanced compression due to radiative cooling. In the case of INTI PF device, the electron energy extends from 58 keV (for N₂) to 256 keV (for Ar). The results indicate that the electron fluence ranges from $2\times 10^{22}$ electrons m${}^{-2}$ for N₂ to $88\times 10^{22}$ electrons m${}^{-2}$ for Ar.

The microstructural modifications due to high energy electrons (8–18 MeV) and their correlation with the yielding behavior of polycrystalline nickel have been investigated. The specimens in the form of strips were irradiated at room temperature for 15 min in the energy range 8–18 MeV using linear accelerator. The comparison of microstructural results of irradiated specimens with that of the un-irradiated ones reveals that radiation deteriorate the surface of the target specimens. The damage was found to be more prominent at the grain boundaries. The tensile tests of both unirradiated and irradiated samples were carried out using Universal Testing Machine at room temperature. An increase in yield stress and loss of ductility was observed in case of irradiated specimens, which became more pronounced with an increase of incident beam energy. These effects are attributed to the interaction of glide dislocations stress fields with the defects produced during irradiation.

The surface of materials plays an important role in their technological applications. In the interest to study the stability of materials and their behavior, we irradiate them by the electrons by using the electron spectroscopy such as the Auger electron spectroscopy (AES) and the electron energy loss spectroscopy (EELS). These methods have proved their good sensitivity to study material surfaces. In this paper, we give some results about the effect of the electron beam irradiating the compounds InP, InSb, InPO₄ and In_xGa_1-xAs. The III–V semiconductors InP and InSb seem to be sensitive to the electron irradiation. This breaks the chemical bonds between the element III and V which leads to an oxidation process at the surface. The AES and EELS spectroscopy are also used to characterize the oxide InPO₄ whose thickness is about 10 Å grown on the substrate InP(100). The irradiation of the system InPO₄/InP(100) by the electron beam of 5 keV energy leads to a structural change of the surface, so that there is breaking of chemical bonds between indium and phosphorus (In–P) and formation of new oxide other than InPO₄. In this study we show an important result concerning the effect of the electron beam on the compound In_xGa_1-xAs by varying the parameter x to obtain In_0.2Ga_0.8As and In_0.53Ga_0.47As. It appears that the electron beam affects In_0.2Ga_0.8As too much in comparison with In_0.53Ga_0.47As. In the case of the irradiation of In_0.2Ga_0.8As, there is breaking of chemical bonds between indium and GaAs leading to formation of indium oxide associated to GaAs.

The effect of UV–IR radiation and electron on polymers has been widely studied. However, independent irradiation effects in different energy domain of electron are of greater interest. We have installed 10 keV electron beam which has zero background of UV–IR using solenoid guided electron beam upto 100 nA/cm². The effect of electron beam changes the microstructure upto a few microns of polymers, which results in the variation in the physical, chemical, and gas permeation properties. The polymer membrane of 25 μm is exposed to an electron beam with 50 μm grid structure on the top. The RGA spectra of polymers during the irradiation were recorded. The optical micrograph shows a depression on the surface due to electron impact and scission of the polymer chains. The gas permeation also gets modified in such a way that permeation rate was higher from the irradiation side.

The electron beam irradiation with subsequent thermal treatment of glasses containing silver ions produces silver nanoparticles (SNPs) arranged in layers. The action of the aperture confined electron beam on glasses containing SNPs results in decomposition of SNPs on perimeter of beam and rearrange of SNPs on the circumference of a larger diameter circle. Both processes are based on the similar mechanism — the drift of silver ions with opposite charges in electric field produced by electron beam.

In this review, our recent results on the electron-beam domain writing (EBDW) on the nonpolar surfaces of LiNbO₃ crystals of different compositions are presented. Under EB irradiation of the nonpolar surfaces, domains nucleated in irradiation points grow frontally along the polar $Z$-direction in a thin (of microns in thickness) surface layer; the driving force is the tangential component of space-charge fields induced by EB in irradiation points. This geometry of the experiment provides a possibility of three-dimensional (3D) characterization of domain patterns using the combination of atomic force microscopy (AFM) and second harmonic generation (SHG) confocal microscopy methods. The obtained results permitted us to relate the main characteristics of domain formation (the domain sizes and velocity $V_f$ of the frontal motion) to the irradiation conditions (the accelerating voltage $U$ of scanning electron microscopy (SEM), EB current $I$, the inserted charge $Q$). The domain depth $T_d$ is controlled by $U$ via the electron penetration depth; the domain length $L_d$ increases linearly with $Q$ owing to the domain frontal growth by the viscous friction law. The electron emission coefficient $\sigma$ affects the domain formation due to the fundamental dependence of $\sigma$ on $U$. In the framework of current approach to EB charging of insulators, the effect of an enhanced conductance on EBDW characteristics is analyzed. The difference between EBDW characteristics observed in varied LiNbO₃ compositions is discussed in the framework of the intrinsic defect structure of LiNbO₃. The obtained results extend the possibility of EBDW application to a wider range of crystals.