Advanced Materials Research Vol. 701

Abstract: The paper is devoted to the analysis of the exchange coupled composite (ECC) media. The principle of ECC media, the switching process and the thermal stability of these media are analysed. The features of ECC media ask for some changes in the design of recording heads; a lot of proposed geometries of these heads are presented. Finally, challenges and possible improvements of ECC media are summarized.

Abstract: Zinc oxide with spherical shaped and flower shaped morphology are prepared by simple one step solvothermal method. The product is subjected to characterization to investigate the morphology and size by using X ray diffraction , semi electron microscopy and transmission electron microscopy. The size of the prepared zinc oxide particle is in the range of 1 micrometer to 3 micrometers. The outer surface of the particles is not smooth but it is rough. The possible formation mechanism for the product is investigated that is further justified by means of structural characterization.

Abstract: Zinc acetate dehydrate as starting material along with diethanolamine as stabilizer, and isopropyl as a solvent were used to synthesis ZnO thin films in different low molarities. Sol-gel spin coating method was used in depositing ZnO on porous silicon substrate surface. In other to prepare substrate, p-type silicon wafer was etched by dilute hydrofluoric acid to modify the surface becomes porous. Field Emission Scanning Electron Microscopy (FESEM) was employed to study the surface morphology. It is found that ZnO thin films were successfully deposited on the substrates which are composed of ZnO nanoparticles with size ~16 nm to ~22nm. Atomic Force Microscopy (AFM) was used to investigate the surface roughness of thin film. The result shows that the surface roughness is increase as the increases of molarities. Photoluminescence (PL) spectra were done in range of 350 nm to 800 nm. The result shows peaks belonging to ZnO, ZnO defects, and porous silicon respectively are appeared.

Abstract: ZnO films were deposited on Cu substrate using electrodeposition and thermal oxidation method. The effect of deposited thin film thickness varied with deposition time was discussed. Synthesized ZnO films were characterized using XRD, FE-SEM and electrical measurement. The results from electrical measurement showed the deposited ZnO exhibits pinched hysteresis IV curves. The synthesized ZnO shows a potential applications and options in production of a non-complex and low cost memristor.

Abstract: nanocrystalline mixed oxides containing magnesium, nickel and chromium (MNCM) have been synthesized as an adsorbent using coprecipitation method and showed its reversible hydrogen storage capacity at ambient conditions using fixed bed. XRD and ICP-MS analyses ensured the adsorbents phase and homogeneity. The microstructure of mixed oxide has been investigated using FESEM and BET and TEM technique respectively. The adsorbent consisted of mesoporous surface with a surface area of 254-370 m²gm^-1 and SAED pattern showed that the adsorbents are poly-crystalline. The mixed oxides exhibited a 3.2 wt% H₂ storage capacity and release 57% of adsorbed H₂. Adsorption enthalpy (H) and entropy (S) change of-27.58 kJ/mol and-70.21 J/mol.K are indicating favorable thermodynamics for reversible hydrogen storage material.

Abstract: Titania nanotube arrays were fabricated by anodic oxidation of the titanium foil in an electrolyte containing F^- ion. In here, will be discuss on effect of difference anodization voltage to the morphologycal, structural and optical properties of the TiO₂ nanotubes. All of these properties were investigated by FESEM, XRD and UV-Vis spectroscopy. The results showed that, the vertical oriented TiO₂ nanotube arrays were obtained at 20 V for 30 min in electrolyte which contained 0.7 g NH₄F and 100 mL NaSO_4. The diameter size of the nanotube is average at 70 nm, the length of the tube is about 1.6 μm and the wall thickness is average at 10 nm. XRD results shows that there are no significant changes of Ti peaks from 4 V to 20 V, but at 28 V some of the Ti peaks were disappeared due to the collapsed of nanotube structure toward compact oxide of TiO₂. The spectral reflectivity were shifted at wavelength of 569 nm with average percentage of transmittance is about 60 % for as-anodized sample.

Abstract: This paper presents a comparative analysis of some of the important characteristics of the carriers of quantum well and quantum dot based laser. Among the characteristics of the carriers, confined carrier concentrations in the gain medium as well as the carrier concentrations at the threshold have been studied extensively by using In_xGa_1-xN based quantum well and In_xGa_1-xN based quantum dot in the active layer of the laser structure. The numerical results obtained are compared to investigate the superiority of the quantum dot over quantum well. It is ascertained from the comparison results that In_xGa_1-xN based quantum dot provides higher density of confined carrier and lower level of carrier concentration required for lasing action. This paper reports the enhancement of confined carrier density and minimization of carrier concentration at threshold of laser using In_xGa_1-xN based quantum dot as the active layer material. Hence, it is revealed that better performances of lasers have been obtained using In_xGa_1-xN based quantum dot than that of quantum well in the active medium of the device structure.

Abstract: Five different paint systems are formulated using mixture of dammar, silver and nanoclay in various compositions. The paint mixture is spin coated onto Aluminium Q-panel (substrate) and then is left to dry at room temperature. This paper describes the characteristics of the dammar based paint system. Adhesion property is evaluated by using the crosshatch method based on ASTM D3359 standards. The wettability property of coating is characterized by using contact angle measurement. The resistances of paint systems are also described against microbial activity by using disc diffusion and agar well diffusion. The result of crosshatch test shows that the coating system containing 50 wt. % of dammar (PD) exhibits an excellent adhesion property. The addition of dammar to polyol helps to increase the contact angle measurement up to 45.8 degree. The largest inhibition diameter zone against E. coli and S. aureus is obtained for the silver nanoclay polyol dammar, PDS3 paints system.

Abstract: This study investigates the effect of carbon nanotubes (CNTs) as conductive fillers and epoxy resin as matrix on the electrical conductivity and hardness property. The different CNTs weight percentage (0 ~ 10 wt.%) were added into the epoxy resin. The dispersion of CNTs in epoxy resin was conducted by high speed mixer through mechanical shearing mechanism. The mixture of CNTs/epoxy was poured into the mold and compression molding was conducted for fabrication of CNTs/epoxy nanocomposites. The electrical conductivity and hardness of CNTs/epoxy nanocomposites by several of CNTs loading concentration were measured by the four point probe and dynamic ultra micro hardness tester. Agglomeration of CNTs in epoxy matrix was observed on fractured surface by scanning electron microscopic. Non conductive epoxy polymer becomes conductor as addition of CNTs. Electrical conductivity of CNTs/epoxy nanocomposites were increased with increasing of CNTs loading concentration. Hardness property of CNTs/epoxy nanocomposites ware reached the highest value at 5 wt.%, and then it was decreased.

Abstract: Effect of nanoMagnesium Hydroxide (MH) nloading amount to the mechanical and physical properties of Low Density Polyethylene (LDPE)/ Poly (ethylene-co vinyl acetate)(EVA) nanocomposite has been described and investigated in this paper. The tensile strength results show that increased amount of nanofiller will decrease and deteriorate the mechanical properties. The elongation at break decreased continuously with increasing loading of nanofiller. Generally, mechanical properties become poorer as loading amount increase. Melt Flow Index values for physical properties also provide same trend as mechanical properties results. Increase filler amount reduced MFI values whereby increased resistance to the flow.