Ionic conductivity study on electron beam irradiated polyacrylonitrile-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.

In situ TEM investigation of electron irradiation and aging-induced high-density nanoprecipitates in an Mg-10Gd-3Y-1Zn-0.5Zr alloy

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3Y-1Zn-0.5Zr(GWZ1031K,wt.%)alloy to improve the hardness.The results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250℃ is 1.64 GPa,which is approximately 64% higher than that of the samples before being treated.It is mainly attributed to γ'precipitates on the basal plane after irradiation and the high-density nanoscale β'precipitates on the prismatic plane after aging,which should be closely related to the irradiation-induced homogenous clusters.The latter plays a key role in precipitation hardening.This result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

Synthesis of a Ag/Ag Cl/PLA membrane under electron beam irradiation for the photocatalytic degradation of methylene blue and chloramphenicol

Polylactic acid(PLA)has been extensively applied in the fields of biology and renewable biodegradable materials because of its superior biodegradability.PLA has excellent potential as a renewable biodegradable adsorbent in wastewater treatment.However,its poor photocatalytic properties have hindered its practical application.In this study,polyvinylpyrrolidone(PVPP)or glutaraldehyde(GA)was utilized as an adhesive agent to prepare Ag/AgCl/PLA photocatalysts with highly efficient visible light photocatalysis on a PLA fabric by utilizing the electron beam irradiation method.The photocatalytic activities of the Ag/AgCl/PLA samples were examined under visible light irradiation to analyze the degradation of methylene blue(MB)and chloramphenicol(CPL).Our experimental results demonstrate that the nanomaterial Ag/AgCl was uniformly distributed on the PLA fiber surface;this can be attributed to the effects of the crosslinking PVPP or GA.Under electron beam irradiation,adding crosslinking PVPP(or GA)is beneficial to the loading of Ag/AgCl onto the PLA.For the composite Ag/AgCl/PLA,the degradation rate for MB was as high as 97% after 150 min of visible light irradiation.The addition of 4 mg/ml of Ag/AgCl solution resulted in the greatest photocatalytic activity for CPL,and we advanced the possible degradation pathways of CPL with the best sample.Additionally,the as-prepared composite Ag/Ag Cl/PLA exhibited favorable antibacterial activity against E.coli and S.aureus,with a bacterial removal rate of >77%.

Effect of Different Doses of Electron Beam Irradiation on the Structure of PAN Precursor Fibers and Resultant Stabilized Fibers

Different doses of electron beam was imposed on the polyacrylonitrile（PAN） precursor fibers before the fibers were stabilized. The effect of electron beam irradiation on the chemical structure, crystallite size of PAN precursor fibers and density, oxygen content, transverse section morphology of the stabilized fibers in the stabilization process were characterized by the use of fourier transform infrared spectroscopy（FTIR）, float- sink procedure, elemental analysis and scanning electron microscope（SEM）, respectively. The results showed that the extent of cyclization was increased and the crystallite size was decreased. We found that electron beam irradiation could accelerate the cyelization reaction and stabilization reaction in the stabilization process through density test and elemental analysis. We also found that the effect of 200 kGy electron beam irradiated fibers with the stabilization time of 75 min was better than that of the original stabilized fibers with 90 min. These results demonstrate that electron beam irradiation can shorten the stabilization time.

2H-SiC Dendritic Nanocrystals In Situ Formation from Amorphous Silicon Carbide under Electron Beam Irradiation

Under electron beam irradiation,the in-situ formation of 2H-SiC dentritic nanocrystals from amorphous silicon carbide at room temperature was observed.The homogenous transition mainly occurs at the thin edge and on the surface of specimen where the energy obtained from electron beam irradiation is high enough to cause the amorphous crystallizing into 2H-SiC.

Removal of endocrine disrupting chemicals from water through urethane functionalization of microfiltration membranes via electron beam irradiation

Polyethersulphone(PES)membranes modified with urethane functional groups were prepared through an interfacial reaction using electron beam irradiation.The removal of eight endocrine disrupting chemicals(EDCs)was studied using both pristine and functionalized PES membranes.The prepared membranes underwent characterization using several techniques,including attenuated total reflectance-Fourier transform infrared(ATR-FTIR)spectroscopy,scanning electron microscopy,contact angle analysis,and measurements of pure water flux.Furthermore,dynamic adsorption experiments were conducted to evaluate the adsorption mechanism of the prepared membrane toward the eight EDCs.The urethane functionalized membranes were hydrophilic(52°contact angle)and maintained a high permeate flux(26000 L/h m^(2) bar)throughout the filtration process.Dynamic adsorption results demonstrated that the introduction of urethane functional groups on the membranes significantly enhanced the removal efficiency of 17β-estradiol,estriol,bisphenol A,estrone,ethinylestradiol,and equilin.The adsorption loading of 17β-estradiol on the functionalized PES membrane was 6.7±0.7 mg/m^(2),exhibiting a 5-fold increase compared to the unmodified PES membrane.The membranes were successfully regenerated and reused for three adsorption cycles without experiencing any loss of adsorption capacity.

Tailoring Bi_(2)Te_(3) edge with semiconductor and metal properties under electron beam irradiation

In pursuit of miniaturization in the semiconductor industry,two-dimensional(2D)materials are used to fabricate new electronic devices.The topological insulator(TI)material bismuth telluride(Bi_(2)Te_(3)),as an emerging 2D material,has potential applications in electronic and spintronic devices due to its unique electrical properties.It is well known that the surface-to-volume ratio increases as the thickness of the material decreases,resulting in a more prominent edge effect.Therefore,for a single-layer Bi_(2)Te_(3),the atomic structure of the edge plays a crucial role in its electrical properties.Here,combining first-principles calculations and in situ transmission electron microscopy(TEM)experimental studies,we report that there are two types of edge structures in single-layer Bi2Te3:semiconducting flat edges and metallic zigzag edges.The dynamic evolution process of the edge structure with atomic resolution shows that the proportions of these two edges change with continuous electron beam irradiation.Our findings demonstrate the viability to use electron beam as an effective tool to precisely tailor the edge of Bi_(2)Te_(3) with desired properties,which paves the way for implementation of single-layer Bi2Te3 in electronics and spintronics.

Synthesis of new silicene structure and its energy band properties

Silicene,silicon analogue to graphene which possesses a two-dimensional(2D)hexagonal lattice,has attracted increasing attention in the last few years due to predicted unique properties.However,silicon naturally possesses a three-dimensional(3D)diamond structure,so there seems to be not any natural solid phase of silicon similar to graphite.Here we report the synthesis of new silicene structure with a unique rectangular lattice by using a coherent electron beam to irradiate amorphous silicon nanofilm produced by pulsed laser deposition(PLD).Under the irradiation of coherent electron beam with proper kinetic energy,the surface layer of silicon nanofilm can be crystallized into silicene.The dynamic stability and the energy band properties of this new silicene structure are investigated by using first-principle calculations and density function theory(DFT)with the help of the observed crystalline structure and lattice constant.The new silicene structure has a real direct bandgap of 0.78 eV.Interestingly,the simulating calculation shows that the convex bond angle is 118°in the new silicene structure with rectangular lattices.The DFT simulations reveal that this new silicene structure has a Dirac-cone-like energy band.The experimental realization of silicene and the theoretically predicted properties shed light on the silicon material with potential applications in new devices.

Effect of Electron Beam Irradiation on Thermal and Mechanical Properties of Polyamide Copolymer/Multiwall Carbon Nanotube Composites

Ternary polyamide(tPA) copolymer is susceptible to degradation when it is irradiated by electron beam(e-beam), and effective methods to avoid degradation and increase gel content are highly desirable for crosslinking.Carboxylated multiwall carbon nanotube(MWCNT) is modified by hydroxyethyl acrylate(HEA) in this paper and used as a co-agent for the e-beam irradiation crosslinking of tPA copolymer. HEA modified MWCNT can function as an effective co-agent for the e-beam irradiation crosslinking of tPA copolymer to increase the gel content and improve the mechanical properties of tPA copolymer. Under an irradiation of 160 kGy, addition of 2 parts per hundred(phr) HEA modified MWCNT into tPA copolymer can increase the gel content of tPA copolymer from about 20% to 40%(mass ratio) and increase the tensile strength from 45 to 59 MPa. The irradiation also affects the glass transition temperature of tPA copolymer by increasing the gel content. The results show that HEA modified MWCNT can act as a nucleating agent to increase the crystallization temperature, melting temperature and crystallinity of tPA copolymer.

Surface alloying of Al films/Ti substrate based on high-current pulsed electron beams irradiation

Ti–Al surface alloy was fabricated using a cyclic pulsed liquid-phase mixing of predeposited 100 nm Al film with a-Ti substrate by low-energy high-current electron beam. Electron probe micro-analysis（EPMA）,grazing incidence X-ray diffraction analysis（GIXRD）,transmission electron microscopy（TEM）, and nanoindentation were used to investigate the characterization of Ti–Al surface alloy. The experimental results show that the thickness of alloy layer is ＊3 lm, and the content of Al in the ＊1 lm thickness surface layer is ＊60 at%. The tetragonal TiAl and TiAl2intermetallics were synthesized at the top surface, which have nanocrystalline structure.The main phase formed in the ＊2.5 lm thick surface is TiAl, and there are few TiAl2and Ti3Al phase for the alloy.Dislocation is enhanced in the alloyed layer. The nanohardness of Ti–Al surface alloy increased significantly compared with a-Ti substrate due to the nanostructure and enhanced dislocation. Since the e-beam remelted repeatedly, the Ti–Al surface alloy mixed sufficiently with Ti substrate. Moreover, there is no obvious boundary between the alloyed layer and substrate.

A scalable versatile methodology to construct micro/nano open-cell polypropylene foam with high oil adsorption capacity and speed

Oil pollution is a serious environmental and natural resource problem.Traditional adsorption materials for oil–water separation have limitations in terms of their preparation cost,reusability,and mechanical properties.Among the conventional adsorption materials,super-hydrophobic/super-lipophilic materials are easily contaminated by oil.In this study,polypropylene(PP)is used as a foam substrate to prepare an open-cell PP foam via hot pressing,supercritical CO_(2) foaming,and electron beam(EB)irradiation.The impact of EB irradiation dose on the open-cell content of PP foam can lead to cell wall rupture,resulting in an open-cell structure that enhances oil-water separation performance.At an absorbed radiation dose of 200 kGy,the PP foams exhibit optimal oil–water separation performance,cyclic compression stability,heat insulation,and preparation cost.The open-cell content of PP foam is increased to 86.5%,the adsorption capacity for diesel oil is 42.8 g/g,and the adsorption efficiency remains at 99.6%after 100 cycles of oil desorption in a complex pH environment.Meanwhile,cracks and nano-voids simultaneously promote the capillary action of oil,and the oil transport rate is 0.0713 g/(g·s).This study provides a new concept for the preparation of open-cell polymer foams that can meet the demand for high oil-absorption capacity under complex acid-base pH conditions.

The effects of electron irradiation on the optical properties of the organic semiconductor polypyrrole

The optical properties of polypyrrole （Ppy） thin films upon 2 MeV electron beam irradiation changes with different doses. The induced changes in the optical properties for Ppy thin films were studied in the visible range 300 to 800 nm at room temperature. The optical band gap of the pristine Ppy was found to be 2.19 cV and it decreases up to 1.97 eV for a 50 kGy dose of 2 MeV electron beam. The refractive index dispersion of the samples obeys the single oscillator model. The obtained results suggest that electron beam irradiation changes the optical parameters of Ppy thin films.

A Facile One-Step Synthesis of TiOe/Graphene Composites for Photodegradation of Methyl Orange

TiO2/graphene composite photocatalysts have been prepared by a simple liquid phase deposition method using titanium tetrafluoride and electron beam （EB） irradiation-pretreated graphene as the raw materials. The products were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The effects of varying the synthesis parameters such as graphene content, concentration of titanium tetrafluoride solution and irradiation dose were investigated. It was found that the preparation conditions had a significant effect on the structure and properties of the final products. The irradiated graphene was covered with petal-like anatase TiO2 nanoparticles, which were more uniform and smaller in size than those in products synthesized without EB irradiation-pretreated graphene. The photocatalytic activities of the products were evaluated using the photocatalytic degradation of methyl orange as a probe reaction. The results showed that the products synthesized using EB irradiation-pretreated graphene exhibited higher photocatalytic activities than those using graphene without EB irradiation pretreatment.

Characterisation of the optical properties of InGaN MQW structures using a combined SEM and CL spectral mapping system

We demonstrate the ability of a combined scanning electron microscope and cathodoluminescence （CL） spectral mapping system to provide important spatially resolved information. The degree of inhomogeneity in spectral output across a multi-quantum well sample is measured using the SEM-CL system as well as measuring the efficiency roll-off with increasing carrier concentration. The effects of low energy electron beam modification on the InGaN/GaN multi quantum wells have also been characterized.

Controllable n-type doping in WSe_(2)monolayer via construction of anion vacancies

The successful applications of two-dimensional(2 D)transition metal dichalcogenides highly rely on rational regulation of their electronic properties.The nondestructive and controllable doping strategy is of great importance to implement 2 D materials in electronic devices.Herein,we propose a straightforward and effective method to realize controllable n-type doping in WSe_(2)monolayer by electron beam irradiation.Electrical measurements and photoluminescence(PL)spectra verify the strong n-doping in electron beam-treated WSe_(2)monolayers.The n-type doping arises from the generation of Se vacancies and the doping degree is precisely controlled by irradiation fluences.Due to the n-dopinginduced narrowing of the Schottky barrier,the current of back-gated monolayer WSe_(2)is enhanced by an order of magnitude and a$8?increase in the electron filed-effect mobility is observed.Remarkably,it is a moderate method without significant reduction in electrical performance and severe damage to lattice structures even under ultra-high doses of irradiation.

Effects of vacancies on interwall spacings of multi-walled carbon nanotubes

We use molecular dynamics (MD) simulations to study the effects of vacancies on tube diameters and interwall spacings of multi-walled carbon nanotubes (MWCNTs). Two types of vacancies, double vacancy and three dangling-bond (3DB) single vacancy, are identified to have opposite effects on the tube size change, which explains the inconsistency of the experimentally measured interwall spacings of MWCNTs after electron beam irradiation. A theoretical model to quantitatively predict the shrunk structures of the irradiated MWCNTs is further developed. We also discuss the fabrications of prestressed MWCNTs, in which reduced interwall spacings are desired to enhance the overall elastic modulus and strength.