Tailoring the surface properties by varying the chemistry and roughness could be of interest for self-cleaning applications. We demonstrate the transformation of hydrophobic ZnO Nano rod (NR) array into superhydrophobic nature by changing the local chemical state and without altering the surface roughness by swift heavy ion (SHI) irradiation. The aligned ZnO NR arrays were irradiated using 150 MeV Ag ions with different fluences from 5E10 to 3E12 ions/cm2. The observed static water contact angles of ZnO NRs samples were 103° ± 3°, 152° ± 4°,161° ± 3°, 164° ± 2°, 167° ± 2°,154 ± 3° and 151° ± 2° for the pristine, ion fluencies of 1E11, 3E11, 5E11, 7E11, 1E12 and 3E12 ions cm−2, respectively. The change in local surface chemistry via formation of surface oxygen related defects due to electronic excitations induced by ion irradiation determine the water dewetting properties. It is found that surface oxygen related defects could be tuned by varying the fluence of the SHIs. Durability tests show that the SHI induced surface oxygen-deficient ZnO NRs have the stable superhydrophobic behavior for more than a year.
Niobium (Nb) thin films, which are potentially useful for integration into electronics and optoelectronics, were made by radio-frequency magnetron sputtering by varying the substrate temperature. The deposition temperature (Ts) effect was systematically studied using a wide range, 25–700 °C, using Si(100) substrates for Nb deposition. The direct correlation between deposition temperature (Ts) and electrical properties, surface/interface microstructure, crystal structure, and morphology of Nb films is reported. The Nb films deposited at higher temperature exhibit a higher degree of crystallinity and electrical conductivity. The Nb films’ crystallite size varied from 5 to 9 (±1) nm and tensile strain occurs in Nb films as Ts increases. The surface/interface morphology of the deposited Nb films indicate the grain growth and dense, vertical columnar structure at elevated Ts. The surface roughness derived from measurements taken using atomic force microscopy reveal that all the Nb films are characteristically smooth with an average roughness <2 nm. The lowest electrical resistivity obtained was 48 µΩ cm. The correlations found here between growth conditions electrical properties as well as crystal structure, surface/interface morphology, and microstructure, could provide useful information for optimum conditions to produce Nb thin films for utilization in electronics and optoelectronics.
We report the growth and characterization of Fe-Ga thin films. These films were RF sputtered onto Si, MgO and quartz substrates by controlling the parameters such as the deposition time, power and substrate temperature. The deposited films were characterized using X-Ray Diffraction, Atomic Force Microscopy and Vibration Sample Magnetometry measurements. The effect of substrates on the structure and magnetic properties were studied. XRD pattern of the deposited films showed the formation of DO 3 phase with L1 2 ordered structure at higher sputtering power. The room temperature deposited films demonstrated higher magnetization (0.08 emu/g) as compared to higher substrate temperature (300 o C) deposited films. The M r /M s ratio was found to be 0.037 for films deposited at room temperature and 0.009 for the substrate temperature 300 o C. L1 2 order was observed in films deposited on MgO and Quartz substrates. Magnetization was also found to be high (M s out of plane = 518 emu/cm 3 , M s in plane = 707 emu/cm 3 ) for films deposited on MgO substrate.
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