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Microwave synthesized nano-sized Cu2ZnSnS4 (CZTS) powder was irradiated with 6 MeV electrons, to investigate stability under radiation. The structural, optical, vibrational and morphological properties were explored using X-ray diffraction, UV–Visible spectroscopy, Raman spectroscopy and scanning electron microscope (SEM). The irradiated sample shows significant change in properties when compared with the pristine sample. X-ray peak broadening analysis has been used to estimate the crystallite size and lattice strain. Raman spectroscopy analysis confirms the transition of ordered kesteriteto disordered kesterite phase after electron irradiation at electron fluence of 4 × 1015 e−/cm2. CZTS nanoparticles having hierarchical flower-like morphology starts agglomerating after electron irradiation as observed from SEM images. The sample did not amorphize up to the highest fluence4 × 1015 e−/cm2employed in this study.

Erosion studies of polyimide, exposed to high energy electrons and atomic oxygen, is necessary in view of its application in space vehicles. Here we present the erosion studies and degradation characteristics of polyimide after its sequential exposure to 1 MeV pulsed electron beam from Microtron accelerator and ~12 eV oxygen ions from a plasma reactor in the laboratory. The fluence of electrons was varied from 5 × 1014 to 2.0 × 1015 electrons/cm2 and that of oxygen ions from ~5 × 1016 to 2 × 1017 ions cm−2. The post irradiated and virgin polyimide samples were characterized by gravimetric analysis and contact-angle measurements. The morphological and spectroscopic information were obtained with Scanning Electron Microscopy, Fourier Transform Infra-Red spectroscopy, and photo-absorption spectroscopy. The erosion yield, surface wettability and the surface roughness were seen to be much higher when exposed to both the radiations as compared to either of them, reflecting the synergetic effects.

The surface properties of substrates made of 3 nm gold nanoparticles embedded on SiO2 nanospheres enabled fingerprint detection of thiabendazole (TBZ), crystal violet (CV) and 4-Aminothiophenol (4-ATP) at an ultralow concentration of ∼10−18 M by surface enhanced Raman spectroscopy (SERS). Gold nanoparticles of an average size of ∼3 nm were synthesized and simultaneously embedded on SiO2 nanospheres by the electron irradiation method. The substrates made from the 3 nm gold nanoparticles embedded on SiO2 nanospheres were successfully used for recording fingerprint SERS spectra of TBZ, CV and 4-ATP over a wide range of concentrations from 10−6 M to 10−18 M using 785 nm laser. The unique features of these substrates are roughness near the surface due to the inherent structural defects of 3 nm gold nanoparticles, nanogaps of ≤ 1 nm between the embedded nanoparticles and their high number. These produced an abundance of nanocavities which act as active centers of hot-spots and provided a high electric field at the reporter molecules and thus an enhancement factor required to record the SERS spectra at ultra low concentration of 10−18 M. The SERS spectra recorded by the substrates of 4 nm and 6 nm gold nanoparticles are discussed.

Excitation functions for 209Bi(α,2n)211At, 209Bi(α,3n)210At and 209Bi(α,4n)209At reactions were calculated using TALYS-1.95 nuclear code from threshold to 50 MeV by invoking suitable options for level densities, nucleon-nucleus optical model potentials and alpha optical model potentials. Statistical factors were used to verify the quality of matching between theoretical model calculations and the experimental data from the EXFOR database. The TTY of 211At calculated using the excitation function of 209Bi(a,2n)211At reaction is compared with existing experimental studies from literature The results of the present study are important for the validation of nuclear model approaches with increased predictive power for 209Bi(α,xn) reactions for the production of 211At.

A system for the electron and photon therapy has been designed and developed at SAMEER, IITB, Mumbai. All the components of the system such as the 270° beam bending electromagnet, trim coils, magne...

We report an in situ synthesis of ruthenium-reduced graphene oxide (Ru-rGO) using 6 MeV electron beam assisted radiolytic reduction method and its supercapacitive behavior. X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) explore Ru nanoparticles of size ~2 nm are decorated on rGO sheets. Raman spectroscopy shows I D/I G ratio increased and formation of bilayer rGO after electron beam irradiation. The defect density in Ru-rGO is increased due to the electron beam irradiation as compared to its counterpart GO. The Ru-rGO based supercapacitor exhibits specific capacitance (128.1 ± 5.59) F g−1 at 10 mV s−1 scan rate. The specific capacitance retention of Ru-rGO is up to 99.4% at 900 cycles while it increases to 130% at 5000 cycles. Discharge curve of the supercapacitor involves three current decay processes viz. activation polarization, ohmic polarization and concentration polarization. The highest energy density of (4.125 ± 0.19) W h kg−1 and power density of 1.44 kW kg−1 are achieved with Ru-rGO supercapacitor. This unique electron beam assisted techniques illustrates a promising method of the fabrication of high performance supercapacitor. BRNS (Research project Number 34/14/05/2015/BRNS), Government of India

MnO2 nanorods-reduced graphene oxide (MnO2-rGO) nanocomposite has been synthesized by facile single pot hydrothermal method. The decoration of crystalline α-MnO2 with tetragonal phase on rGO nanosheets has been confirmed by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field emission (FE) properties of MnO2-rGO emitter have been investigated and it exhibited enhanced FE properties demonstrated by lower values of turn-on and threshold field in contrast to the pristine MnO2 and rGO emitter. The superior FE characteristics of the MnO2-rGO emitter are attributed to the modulation of morphological properties offering high aspect ratio as well as electronic properties enhancing the density of states. The observed FE characteristics of MnO2-rGO emitter indicates the potential of using in vacuum microelectronics/nanoelectronics.

Exploiting the photosensitive property of BiFeO3 thin films, we demonstrated a resistive switching memory cell having low Vset voltage (+2.0 V), an ultrahigh ON/OFF ratio of ∼107 and a good retention time of more than 106 s. Synthesis conditions were optimized during a sol–gel-assisted spin-coating method to get phase-pure BiFeO3 films on Al substrate, at room temperature. Current–voltage analysis revealed that during optical illumination, photon-induced charge carriers migrate towards their respective electrodes along grain boundaries under an externally applied field, which initiate a substantial shift in the normal Vset of +10.4 V to a lower voltage (+2.0 V). The Poole–Frenkel emission at the metal/BiFeO3 interface is proposed and the role of electronic reconstruction at the interface is further investigated. Thus the write process in BiFeO3-based resistive-switching devices can be modulated in a controlled manner, which has the potential for integrating current resistive switching (memristive) memory device technology towards exciting optomemristive device technology.

Nanostructures of dielectric materials decorated with metal nanoparticles are of great scientific interest; however, the involved synthesis methods are complicated and require multistep chemical processing, including functionalization of the dielectric surfaces. In the present work, without chemical processes, silver nanoparticles of average sizes in the range of 11 to 15 nm were in-situ synthesized and decorated on SiO2 nanospheres in a single step process by irradiating a solution (AgNO3–polyvinylpyrrolidone (PVP)–SiO2 nanospheres) with 6 MeV electrons at 1.5 × 1015 e−/cm2, 3.0 × 1015 e−/cm2, and 4.5 × 1015 e−/cm2 fluences. The electron irradiated solutions were characterized with different surface and other techniques. The results revealed that the SiO2 nanospheres were uniformly decorated with Ag nanoparticles, and the prominent chemical bonds involved were Ag–O, Si–O–Ag, and Si–Ag. Moreover, the sizes and the decoration density of Ag nanoparticles could be tailored by varying electron fluence. The Su...