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We have successfully synthesized multi-layer graphene oxide and graphene oxide based magnetic nanocomposite (M/GO) by microwave-assisted modified Hummers’ method for removal of toxic lead (Pb2+) and cadmium (Cd2+) ions from aqueous solution. The X-ray diffraction spectra of synthesized graphene oxide and M/GO confirm increased interlayer spacing along c-axis. Raman spectra revealed the good quality of synthesized GO and M/GO. The wrinkles were seen in the SEM images of synthesized graphene oxide. The presence of conjugated double bond (C C) and carbonyl (C O) were confirmed by using the UV–Vis spectroscopic spectra. Brunauer–Emmett–Teller (BET) analysis showed high (126 m2/g) surface area M/GO composite which accounts for large number of active binding sites for the adsorption of heavy metal ions. The adsorption studies revealed that Pb2+ ions were efficiently adsorbed on GO sheets. Interestingly, M/GO showed better adsorption for cadmium ions.

The condensation transport coefficients are higher on the metallic surface because of the high thermal conductivity of metallic surfaces. However, the metallic surfaces have a higher affinity to water in the condensation process which leads to corrosion and results in damage to the condensing metallic surface. Low surface energy and low wettability surfaces promote efficient condensation in drop mode. Therefore, several surface modification techniques have been adopted for modifying the surface wettability of the metallic surfaces. Teflon coating on the metallic surface has been an economically viable and simple method for fabricating low surface energy coating on metallic surfaces. In this work, Cu coil is coated with PTFE film for fabricating hydrophobicity on Cu helical coil. Moist air condensation experiments are carried out on Teflon coated and bare Cu coil to investigate the effect of Teflon coating on the coil. In addition, the effect of moist ambient conditions on the Teflon coated coil is addressed to examine the aging of the Teflon coating on the Cu coil. The results show that the characteristics of hydrophobic Teflon coating deplete with increases in exposure time so the dropwise condensation transits into mixed condensation and ultimately in film mode as the coil is exposed to repeated condensation cycles. The results of the present study are useful to appropriately investigating in which all applications the Teflon coating can be implemented such that all its properties are retained in that time duration.

Ion beam sputtering, known as potential technique for producing nanoripple on various surfaces having wide range of applications. Along with nanoripple, triangular features are also superimposed, limiting their use for some potential applications. Here we are reporting evolution of triangular features on Ge (100) surfaces under low energy (300–1000 eV) Xe ion irradiation at room temperature for angles of incidence (61°–80°) and ion fluences of (5.34 × 1017−8.01 × 1018 ions cm−2). Triangular features appear with the onset of ripple formation and disappear when the ripple periodicity is lost. These features formation depend not only on material but also depend on the ratio of the ion/target mass. In comparison with numerical simulations based on modified anisotropic Kuramoto-Sivanshinsky equation, we find good agreement for the evolution of base angle and lateral length for the triangular features with ion incidence angle. The dynamics of triangular feature with ion incidence angle and ion fluence have been reported. Ion-incidence angle dependency is adequately replicated in numerical simulations. Experimentally the base angle and lateral length increases with increase in ion incidence angle, similar trend is observed in numerical simulation.

Low energy ion beam-induced nanoscale ripple patterns have attracted attention due to their use in various technological applications. Making defect free, highly regular, and low wavelength (∼30 nm) ripple patterns is still under investigation as ripple patterns forms over triangular features (elevations and depressions) that curtail their use in an application. In this work using 300 eV Ar+ ion beam, the topographic evolution of such triangular features at elevated temperature up to 500°C for ion fluences of 2×1018 to 1×1019 ions.cm−2 was examined. Triangular features remain intact well up to 200°C with a marginal decrease in the base angle. Above 300°C, triangular features start corrugating and, finally both triangular features and ripple vanished at 500°C. The experimental findings were compared using modified anisotropic Kuramoto-Sivanshinsky (AKS) equation by Loew and Bradley (LB) incorporating simultaneously diffusion coefficient and third order dispersion term. Temperature-induced effects are adequately replicated; dispersion produces the triangular features and diffusion help to grow it further. In experiment base angle and lateral length of the triangles decreases with increasing temperature, similar trend was observed in numerical simulations by varying the diffusion coefficient.

In the present communication, structural, microstructural and electrical properties of La0.5Nd0.2Ca0.3MnO3 (LNCMO) and La0.5Nd0.2Sr0.3MnO3 (LNSMO) mixed valent manganite films, grown on single crystalline (0001) Al2O3 (ALO) substrates using pulsed laser deposition (PLD) technique, have been studied. After deposition, one set of LNCMO and LNSMO films were annealed in oxygen environment at 500 °C (hereafter referred as LNC–A & LNS–A, respectively) and compared their properties with other set of PLD as–grown LNCMO and LNSMO films (hereafter referred as LNC and LNS, respectively). Single crystalline growth of LNCMO films and polycrystalline growth of LNSMO films have been identified through X–ray diffraction (XRD) measurement. Atomic force microscopy (AFM) measurement for morphological studies indicates that divalent dopant and oxygen annealing process play an important role in governing the grain growth and surface nature of the studied films. A decrease in the value of resistance (R) and impedance (Z) with increase in frequency under the applied magnetic field (H = 1 T) has been observed for all the studied films. For LNC & LNC–A films, reactance is found to decrease monotonically with increase in frequency throughout its range studied while for LNS and LNS–A films, reactance initially increases followed by reduction in its value with increase in frequency under 0 and 1 T magnetic field has been observed. The variation in MR for LNS and LNS–A films has been discussed in the context of charge transport mechanism and Lorentz force. Further, to discuss the role of grain and grain boundaries, nyquist plots and their suitable fits under zero and 1 T external magnetic field have been investigated for all the studied mixed valent manganite films. Important role of phase separation scenario in studied manganite films has been discussed in detail based on magnetization measurement. Double magnetic phase transition and fluctuations in derivative of magnetization have been ascribed to the phase separation scenario of LNCMO / ALO and LNSMO / ALO mixed valent manganite thin films.

We report current–voltage (I–V) device characteristics of pulsed laser deposition (PLD) grown La0.5Gd0.2Ca0.3MnO3 (LGCMO) manganite thin films on single crystalline (100) Nb:SrTiO3 (SNTO) substrates. LGCMO films were irradiated using 100 MeV O+9 swift heavy ions (SHI). The θ–2θ X–ray diffraction (XRD) and atomic force microscopy (AFM) measurement were performed at room temperature, respectively, for understanding the structural and microstructural behaviors of the films. The current–voltage (I–V) data were taken under the bias voltage applied across LGCMO/SNTO p–n interfaces at room temperature. Observed I–V behaviors for all interfaces have been discussed in the context of lattice strain, grain size and grain boundary density. To study the effect of annihilation on the irradiated LGCMO films, 50 nm thick ZnO layer was grown on the surface of LGCMO/SNTO films using chemical solution deposition (CSD) method under oxygen environment with a controlled flow. XRD, AFM and I–V measurements were performed again for annealed ZnO/LGCMO interfaces. Observed I–V characteristics across ZnO/LGCMO interface have been discussed in details in the context of annihilation induced modifications in the interface, structural strain and surface morphology.

The bouncing dynamics of impacting water droplet on low energy ion beam produced superhydrophobic PTFE surfaces was investigated for the self-cleaning application. Ion beam with 300 eV and 800 eV energies was used to produce nanostructures on PTFE surfaces having the bouncing behaviour. The bouncing dynamics of water droplet was studied using dynamics parameters like spreading factor (β), contact time (tc), time of flight (ta) and number of bounces. The maximum spreading factor for the impact velocity of 0.5 m s−1 and 1.0 m s−1 was found to be 1.4 and 2.0, respectively for both 300 eV and 800 eV irradiated surfaces. The contact time of impacted droplet on 800 eV irradiated surface with 0.5 m s−1 velocity was found to be much lower (tc = 13.00 ms) than 300 eV ion irradiated surface (tc = 19.67 ms). Post impact bouncing number as high as 14 was found for 800 eV irradiated surface. Depending on ion energy and irradiation time the surface was converted from complete wetting to complete bouncing at low impact velocity of 0.5 m s−1 and from complete bouncing to partial bouncing at 1.0 m s−1. The self-cleaning property on 800 eV irradiated surface was successfully demonstrated using carbon powder.

The surface wettability of polytetrafluoroethylene (PTFE) was investigated with low energy Ar+ ion beam irradiation varied from 300 eV to 800 eV both at normal and oblique angle of incidence (0°–70°) and at a low irradiation time of few 10 s of seconds. A remarkable change in surface wettability was observed, surface became hydrophobic to superhydrophobic just at 800 eV energy and in 30 s time. A systematic increase in the contact angle was observed with increase in beam energy and irradiation time. For a given ion energy and a threshold irradiation time, the hierarchical protrusions developed that leads to the rolling and bouncing of water droplet even on the horizontal PTFE surface. For the above energy range, the rolling speed was found to be in the range of ~19–31 mm/s. This induced wetting behaviour due to ion irradiation leads to the Cassie-Baxter state as confirmed by the calculation of sliding angle, contact angle hysteresis (CAH) and surface free energy (SE). The CAH values were found to be reduced from 18° for untreated surface (SE ~ 20 mN/m) to 2° for 800 eV, 180 s irradiated surface (SE ~ 0.35 mN/m) at normal incidence.

Ion beam irradiation produced ripple nanopatterns on Si surface was used to produce a highly dense and sensitive SERS substrate for detecting Dichlorvos pesticide below the permissible limit. The wavelength of the ripple varied from 22 nm to 35 nm by changing ion beam energy from 200 eV to 500 eV. Highly regular nanoparticles arrays were produced down to 22 nm wavelength choosing the proper ion beam parameter and ripple orientation during deposition. The shape of deposited nanoparticles on ripple nanostructures changed from elongated to spherical upon increasing wavelength and amplitude of ripples at different ion energies. The optimization of SERS intensity was carried out using crystal violet dye which revealed that the maximum enhancement (enhancement factor ~107) occurred for the 300 eV irradiated substrate. The optimized substrate was used for detecting Dichlorvos up to 1 ppm level without using any binder molecule.

Multiferroic thin films of BiFe0.98Co0.02O3 (BFCO) were grown on Al2O3 (ALO) substrates having a buffer layer of Al (2%) doped ZnO (ZAO) prepared by using chemical solution deposition (CSD) method. Effect of annealing temperature and annealing atmosphere on the structural, microstructural, dielectric, leakage, transport, magnetic and magnetodielectric (MD) properties of films have been investigated. BFCO/ZAO/ALO films grown under oxygen atmosphere show better crystallinity, smooth surface and slightly larger grain size than that of the films annealed in air. Lower leakage current, higher dielectric constant, lower dielectric loss, lower a.c. conductivity and larger MD and magnetoimpedance (MI) effects have been observed for the film annealed at 550 °C under oxygen atmosphere. In order to verify the state of oxygen vacancies, photoluminescence spectra have been studied. Room temperature magnetic behavior of the BFCO/ZAO/ALO films has been studied by performing magnetization measurements. The effect of magnetic field on the dielectric constant and impedance (MD & MI) have been discussed on the basis of magnetostriction effect and mobility of interfacial charges at grain boundaries and bilayer interface.

Deposition of various coatings on Al surface is required for variety of functional applications such as for better corrosion resistance, improvement in conductivity, wear resistance etc. These coatings are normally applied on Al surface followed by well-known zincating process (galvanic displacement) in order to obtain subsequent adherent overlayer coatings. Adhesion of these overlayers depends on uniformity of Zn films on Al surface and researchers normally follow either single zincating or double zincating process to eliminate oxide layer interference. However, it has been established over the years that double zincating is a better technique in comparison to single zincating to produce a uniform Zn-films on Al surface. It is to mention here that Al substrate undergoes nitric acid dip followed by single zincating prior to double zincating and is a very important step. A quiet good amount of research has already been devoted to obtain various adherent coatings on Al and Al-alloys and to analyze the nucleation mechanism during single and double zincating processes. However, the underline mechanism of nitric acid etching and its role on subsequent Zn-nucleation is yet to be fully understood. In view of this, in the present study, a systematic effort has been made to elucidate the role of nitric acid etching followed by single zincating on Zn nucleation and growth mechanism during subsequent second zincating. For this, we have studied the time-dependent zinc nucleation on 99.95% pure Al during single as well as double zincating. These Zn-nucleation and growth behavior on Al surface was monitored using AFM, FESEM and FIB-cut cross section image investigations in detail. Difference in nucleation and growth pattern of Zn on Al during two zincating processes was analyzed. Apart from these, the porous surface obtained after nitric acid dissolution was investigated in depth under AFM and FESEM along with EDS. Non-gravimetric method such as Rutherford Backscattering Spectrometry (RBS) was used to determine the deposition rate of Zn during competitive galvanic deposition of Zn and alkaline dissolution of Al while zincating. The Zn grain size obtained from AFM image was verified by GIXRD analysis. Open circuit potential (OCP) was monitored during single as well as double galvanic displacement processes to understand Zn nucleation behavior and correlated with the morphological data. The observed results will be discussed in terms of electrochemical processes involved, change in chemical nature of the Al surface and porous layer formation due to nitric acid etching and thermodynamic supersaturation on Zn nucleation. Figure 1

Modified alloy zincate (MAZ) is a surface-treatment process for depositing Zn on Al by galvanic displacement reaction prior to application of functional coatings. Two-step zincating i.e. double zincating (DZ) is a preferred technique in comparison to single zincating (SZ) because of imparting excellent adhesion of coatings on Al. Prior to second step of zincating during DZ, the single zincated Al substrate undergoes nitric dissolution. In this study, the intriguing role of this nitric acid etching on second step nucleation and growth of Zn has been investigated in detail. For this, time dependent Zn-nucleation and growth morphology on Al surface was monitored by AFM and FESEM examinations and revealed scattered but coarse nucleation during SZ; and finer nucleation along with uniform coverage of Zn during DZ. Post single zincating, nitric acid etch led to generation of micro/nanoporous Al surface as revealed by microscopic investigations. The porous Al surface along with trace amount of noble metals such as Cu and Fe was found to play significant role on Zn root growth into Al matrix and fine grain Zn deposit on top surface confirmed by cross-section FESEM analysis of focused ion beam (FIB) cut Zn/Al sample. Rutherford Backscattering Spectroscopy (RBS) was used as a non-destructive technique to estimate Zn film thickness and growth rate. The observed Zn nucleation and growth results were further substantiated by analyzing the open circuit potential (OCP) data during zincating. Difference in nucleation and growth pattern of Zn on Al surface during SZ and DZ was fundamentally understood with the help of classical nucleation theory and galvanic kinetics.

The biggest global challenge in this century is to meet the ever increasing demand for electricity, vehicular fuel and potable water for a growing world population with high aspiration for a better quality of life, while mitigating CO2 and other greenhouse gas emission and limiting global warming and temperature rise below 2°C, as per the agreement at the United Nations Forum for Climate Change (UNFCC) at Paris in December 2015. The present paper summarises three ways in which nuclear energy contributes in solving problems of global warming and a carbon free atmosphere.