Sharif Digital Repository

Titania thin film system containing noble metallic nanoparticles such as Au, Ag, and Cu have been prepared by utilizing radio frequency reactive magnetron cosputtering method. The structural and morphological properties of the thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). Surface chemical composition of the films was determined by X-ray photoelectron spectroscopy (XPS). Optical properties of the TiO 2 annealed films containing Au, Ag, and Cu metallic nanoparticles were investigated by UV-visible spectrophotometry showing surface plasmon resonance of the metals. The photocatalytic activity of all synthesized samples annealed at 600 °C in an Ar +... 

We have studied formation of Au-Ag alloy nanoparticles in sputtered SiO 2 thin films. Silica thin films containing Au-Ag nanoparticles were deposited on quartz substrates using rf reactive magnetron co-sputtering technique. The films heat-treated in reducing Ar + H 2 atmosphere at different temperatures. They were analyzed by using UV-vis spectrophotometry, atomic force microscopy and X-ray photoelectron spectroscopy (XPS) methods for their optical, surface morphological as well as structural and chemical properties. The optical absorption of the Au-Ag alloy nanoparticles illustrated one plasmon resonance absorption peak located at 450 nm between the absorption bands of pure Au and Ag... 

Gold-silver alloy nanoparticles with various Au concentrations in sputtered SiO2 thin films were synthesized by using RF reactive magnetron co-sputtering and then heat-treated in reducing Ar + H2 atmosphere at different temperatures. The UV-visible absorption spectra of the bimetallic systems confirmed the formation of alloy nanoparticles. The optical absorption of the Au-Ag alloy nanoparticles exhibited only one plasmon resonance absorption peak located at 450 nm between the absorption bands of pure Au and Ag nanoparticles at 400 and 520 nm, respectively, for the thin films annealed at 800 °C. The maximum absorption wavelength of the surface plasmon band showed a red shift with increasing... 

A double-tube vapor phase transport system has been used to grow ZnO nanostructures. Nanopillars, nanorods and nanowires of zinc oxide were synthesized on Au nanoparticle catalyst depending on source-substrate distance and temperature gradient in the quartz tube. In addition, influence of growth time and substrate temperature on the morphology of the nanorods and nanowires were also investigated. The scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to further understand the nanostructures growth mechanism on various temperatures and growth time steps. Longer length (>4μm) with hexagonal-cross-sectional nanowires, in [002]... 

In this work, formation of gold nanoparticles in radio frequency (RF) reactive magnetron co-sputtered Au-SiO 2 thin films post annealed at different temperatures in Ar + H 2 atmosphere has been investigated. Optical, surface topography, chemical state and crystalline properties of the prepared films were analyzed by using UV-visible spectrophotometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD) techniques, respectively. Optical absorption spectrum of the Au-SiO 2 thin films annealed at 800 °C showed one surface plasmon resonance (SPR) absorption peak located at 520 nm relating to gold nanoparticles. According to XPS analysis, it was... 

In this study, ZnO-GO, and ZnO-ROG nanocomposites were synthesized by the green chemistry method to study their antibacterial activity. XRD pattern and XPS confirmed that the nanocomposites successfully were synthesized. The UV–vis spectroscopy results showed the bonding between ZnO nanoparticles and GO sheets can engineer the semiconductor band gap and shift the absorption edge to longer wavelengths as compared to pure ZnO. The inhibition rate of ZnO nanoparticles, GO, and RGO sheets after 12 h of contact with E. coli were 84 %, 81 %, and 73 %, respectively. Inhibition rate for Z-1GO, Z-5GO, Z-10GO, Z-1RGO, Z-5RGO, and Z-10RGO nanocomposites were 89 %, 92 %, 94 %, 85 %, 89 %, and 91 %... 

Three-dimensional macroporous fluorine-doped tin oxide (p-FTO) films were successfully deposited using commercial ink of FTO powder and SnCl2 salt via Dr. Blade method. Various features of p-FTO thin films were studied as a function of the ink composition and sintering temperature. The morphological studies corroborated formation of porous, uniform, and crack-free FTO films after annealing at 300 °C for 10 min in air. X-ray diffraction pattern demonstrated development of highly crystalline FTO films. The lowest sheet resistance of 47 Ω/□ was obtained for the p-FTO film with a thickness of 21 μm. The capacitance of thin p-FTO films was investigated using a three-electrode system and the... 

The growth of harmful microorganisms is a severe threat to human life. Nowadays, it is necessary to prepare antimicrobials materials with high biocompatibility properties. Hence, the use of nanomaterials and their nanocomposites has been proposed as a suitable way to obtain safe and potent antibacterial materials. Recently, several studies have been conducted on the antibacterial properties of metal oxide and graphene oxide (GO) nanomaterials individually. This study investigated the synergistic effect of GO and copper oxide (CuO) as a nanocomposite. CuO-GO nanocomposite containing 5%, 15%, 25%, 50%, and 75% of GO were synthesized to study antibacterial properties. X-ray diffraction (XRD)... 

Three-dimensional macroporous fluorine-doped tin oxide (p-FTO) films were successfully deposited using commercial ink of FTO powder and SnCl2 salt via Dr. Blade method. Various features of p-FTO thin films were studied as a function of the ink composition and sintering temperature. The morphological studies corroborated formation of porous, uniform, and crack-free FTO films after annealing at 300 °C for 10 min in air. X-ray diffraction pattern demonstrated development of highly crystalline FTO films. The lowest sheet resistance of 47 Ω/□ was obtained for the p-FTO film with a thickness of 21 μm. The capacitance of thin p-FTO films was investigated using a three-electrode system and the... 

The growth of harmful microorganisms is a severe threat to human life. Nowadays, it is necessary to prepare antimicrobials materials with high biocompatibility properties. Hence, the use of nanomaterials and their nanocomposites has been proposed as a suitable way to obtain safe and potent antibacterial materials. Recently, several studies have been conducted on the antibacterial properties of metal oxide and graphene oxide (GO) nanomaterials individually. This study investigated the synergistic effect of GO and copper oxide (CuO) as a nanocomposite. CuO-GO nanocomposite containing 5%, 15%, 25%, 50%, and 75% of GO were synthesized to study antibacterial properties. X-ray diffraction (XRD)... 

We have investigated the effect of bias voltage on sheet resistance, surface roughness and surface coverage of Co/NiO x magnetic bilayer. In addition, interface topography and corrosion resistance of the Ta/Co/Cu/Co/NiO x /Si(1 0 0) system have been studied for Co layers deposited at an optimum bias voltage. Atomic force microscopy (AFM) and four point probe sheet resistance (Rs) measurement have been used to determine surface and electrical properties of the sputtered Co layer at different bias voltages ranging from 0 to -80 V. The Co/NiO x bilayer exhibits a minimum surface roughness and low sheet resistance value with a maximum surface coverage at Vb=-60 V resulted in a slight increase of... 

The effect of bias voltages on the statistical properties of rough surfaces has been studied using atomic force microscopy technique and its stochastic analysis. We have characterized the complexity of the height fluctuation of a rough surface by the stochastic parameters such as roughness exponent, level crossing, and drift and diffusion coefficients as a function of the applied bias voltage. It is shown that these statistical as well as microstructural parameters can also explain the macroscopic property of a surface. Furthermore, the tip convolution effect on the stochastic parameters has been examined. © 2005 The American Physical Society  

We report on the MoS2 and MoOx (x = 2 and 3) composite thin layers, electrodeposited, onto a Florine doped Tin Oxide (FTO) substrate. Our results show a change in relative content of these compounds in different thicknesses ranging from ∼20 to 540 nm. This change in the relative content at different thicknesses leads to a change in optical and electrical properties including bandgap and the type of semiconductivity. A sharp transition from p to n-type of semiconductivity is observed by scanning tunneling spectroscopy measurements. We find that the spin-orbit interaction of Mo 3d electrons in the MoS2 and MoO3 enhances by significant reduction of the MoO3 content in thicker layers. © 2017...