Advanced Materials Research Vols. 79-82

Abstract: Super-hydrophobic membrane has received extensive attention from basic theories and practical applications. The properties of the super-hydrophobicity of membrane are strongly dependent on the prepared method, which is attracting increasing concerns worldwide. The properties of super-hydrophobic membrane are dominated by many factors including the chemical composition and the morphology of the surface. In this work, a simple method to fabricate super-hydrophobic membrane with weak hydrophilic polyethersulphone (PES) via a sol-gel process is reported. The weak hydrophilic PES membrane was used as a membrane-based, which was dipped into precursor Sol firstly. After heat treatment, the membrane was dipped into the fluoroalkylsilane solution and then dried by again a heat treatment. The super-hydrophobic and porous PES membrane was characterized by Fourier-Transform Infrared Spectrometers (FTIR), contact angle goniometer, atomic force microscope (AFM). The results showed that the contact angle of super-hydrophobic membrane was up to 154°treated by precursor sol for 20min and fluorinated for 20h. The hydrophobic functional groups on the membrane surface were fluorinated groups (-CF3, -CF2, and -CF) and -CH3. The AFM images results showed the membrane surfaces have micro-/nanometer crater-like protrusions. Those protrusions contributed for the rough surface of membrane, and the root mean square (rms) roughness was about 350.9nm. The hydrophobic groups and the surface roughness structure together lead to the super-hydrophobicity of the porous membrane.

Abstract: Mixed molybdenum-tungsten oxides of varying stoichiometry (MoxW1-xO3, 0 < x <1) were prepared by sol-gel deposition from peroxo-polymolybdotungstate solutions onto conductive fluorine doped tin oxide (FTO) coated glass substrates. The compositional and structure properties were characterized for MoxW1-xO3 films annealed at 450°C using energy-dispersive spectroscopy and X-ray diffraction measurements. The optical transmittance of the films were recorded with respect to air in the reference beam in a UV-Vis-NIR spectrophotometer. The transmittance modulation of the mixed oxide films were enhanced compared to the pure WO3 film and very broad spectral modulation features were observed for mixed oxide. Cyclic voltammetry and chronoamperometry measurements were conducted to estimate ion storage capacities and reversibility of the films during the coloring/bleaching process for the mixed metal oxide films in an electrolyte solution of lithium perchlorate in propylene carbonate. The subtle interplay between structural and compositional properties due to the uniform mixing of Mo and W oxide components shows that electrochromic and lithium ion transport properties are moderately enhanced relative to those of single-component WO3.

Abstract: The structural and surface properties of thin, metal oxides films can be tailored by including various additives in the precursors’ systm. The paper presents a comparative approach concerning the properties of WO3 thin layers obtained via spray pyrolysis deposition (SPD) using hydrophilic and hydrophobic polymers as additives. The influence of the thin films composition and morphology is reported, considering their applications of photocatalyst in the advanced treatment of waters resulted in the dye finishing industry, containing methylen blue and methyl orange.

Abstract: Theoretical study on the geometric structures and magnetic properties of small (FeAl)n (n=1-4) clusters has been carried out at the BPW91 level. In all the (FeAl)n clusters, the iron atoms are brought together, yielding a maximum of Fe-Fe bonds, and the aluminum atoms are located around a Fe core with a maximum of Fe-Al bonds which is different the bulk ordered FeAl alloy dominated by the Fe-Al bonds. As opposed to the bulk FeAl with non-magnetic, the small nano-clusters are highly magnetic moment dominated by Fe-Fe clustering.

Abstract: Granular (FePt)100-x–(NiO)x nanocomposite thin films with x in the range of 0 – 42 vol.% were fabricated on a natural-oxidized Si(100) substrate. It is found that both the coercivity and FePt domain size decrease with increasing NiO content for the (FePt)100-x–(NiO)x films. When the FePt-NiO nanocomposite film with NiO content of 10.4 vol.% is post-annealed at 750 °C with a high heating ramp rate of 100 °C/sec, the in-plane coercivity (Hc//) and perpendicular coercivity (Hc⊥) of the FePt films are 6.4 and 5.5 kOe, respectively. On the other hand, we used conductive atomic force microscope (CAFM) to confirm that the NiO compound is distributed at grain boundary of FePt grain that will constrain the domain size of FePt and obtain isolated magnetic domains. These results indicate that NiO addition is beneficial to enhance recoding density and reduce media noise of the FePt magnetic film.

Abstract: The experimental result shows that the preferred orientations of NiO thin films are closely related to the working pressure of argon. All of NiO(111), NiO(200), and NiO(220) diffraction peaks are observed in the XRD patterns and exhibited random orientation of NiO film when the film is deposited in low Ar pressure of 5 mTorr. As the Ar pressure is increased to 20 mTorr, only NiO(200) peak appears and shows (200)-textured NiO films. However, the lattice parameter of NiO film deposited in high Ar pressure of 20 mTorr is 0.424 nm, which is much larger than that of NiO bulk (0.417 nm). The lattice parameter can be decreased by post-annealing the film due to the interstitial Ar atoms are released from the NiO lattice and it reduces continuously from 0.423 to 0.417 nm as the NiO films are annealed from 300 to 600 °C. Therefore, post-annealing the NiO film deposited in higher Ar pressure will reduce the lattice misfit between the NiO and L10 FePt film that is beneficial to improve the perpendicular magnetic anisotropy of FePt film.

Abstract: In this paper, NiCoCrAlY coating was deposited by cold spraying with helium gas under the temperature of 500°C and pressure of 2.6 MPa. The microstructure of the coating was characterized through surface morphology and cross-sectional microstructure by scanning electron microscopy and X-ray diffraction analysis. The results showed that the coating is deposited through intensive plastic deformation of the spray particles by high-speed impact, and no oxygen phenomena discovered in the cold spray process. We also detected the micro-hardness using the Digital Vickers Microhardness Tester. Result revealed that a compact texture and high micro-hardness NiCoCrAlY coating can be obtained by cold spray.

Abstract: The WO3 film was prepared by dip coating method with WCl6 as the soure of tungsten and P123 as the structure-directing agent. The crystalline phase and microstructure of the film were characterized through XRD and TEM techniques, respectively. It was found the film annealed at 300°C for 4h mainly was amorphous WO3 with a little monoclinic WO3. The TEM micrographs revealed the film was partly ordered mesoporous and the mean pore diameter was about 5nm. The measurements of the cyclic voltammetry suggested that the WO3 film had a good electrochromic reversibility performance. The ratio of amount of charge intercalated and amount of charge deintercalated during the cyclic voltammetry, was over 99%. The film possessed a very short respond time which was only about 3.1s.

Abstract: Lanthanum (La) nano-films prepared by a self-assembled technique on a silicone-based material surface, was studied by using an all-round functional Turbiscan LAB stability analyzer and X-ray fluorescence analysis (XRF) as well as atomic force microscope (AFM). La content introduced in the assembled nano-film reached a maximum at pH value between 5 and 6. In the preparation of colloidal sol, no phase separation took place at 60 °C where the colloidal particles uniformly and stably dispersed in the solution. The optimum topographic feature was observed after 24 hours, whence self-assembled process was performed. The particle dispersion of the assembled film was uniform and compact at the optimum EDTA to La molar ratio 0.5.

Abstract: Radio frequency (rf) magnetron sputtering of polytetrafluoroethylene (PTFE) using argon as the working gas was used to prepare hydrophobic fluorocarbon films on a polypropylene substrate. The morphology, structure and hydrophobicity of the fluorocarbon films were analyzed by means of SEM, AFM, XPS and contact angle determination. The growth pattern in this system was a typical one-dimensional (1-D) Volmer-Weber growth mode. The films demonstrated dependence of structure and hydrophobicity on the conditions of preparation. The contact angle decreased with increasing discharge power and increased with increasing pressure. Those trends are attributed to the presence of differing proportions of -CF3, -CF2-, -CF-, and -C- in fluorocarbon thin films prepared with different energy.