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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.

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.

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.

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.