International Journal Of Nanoscience and Nanotechnology
Volume:8 Issue: 2, Spring 2010

In this research, the high-energy planetary mill was employed to produce nanocrystalline Ti-50Al(γ)(at%) powders. Initial powders were mechanically alloyed in 99.9999% and 90% purities of Argon and also Air atmosphere with alloying times up to 50h. The effect of impurity of Argon atmosphere on the microstructure and the rate of phase transformation of Ti-50Al were investigated during mechanical alloying and after annealing at 1000°c. The results showed that the formation of nanostructure TiAl(γ) phase had directly related to the impurities of atmosphere in vials. The impurity of the atmosphere could delay the rate of amoprphization during mechanical alloying and decrease the rate of mechanical alloying process beside some unwanted phases which were produced in powder mixture. The powder particles produced in the high purity Argon atmosphere seemed to be finer than those in the atmosphere. The X-ray patterns, SEM analysis, changes in grain size and DTA test were studied during mechanical alloying and after annealing.

In this paper, synthesized (raw) multi-walled carbon nanotube (rMWCNTs) surfaces were modified with chitosan and β-cyclodextrin using Chen’s soft cutting technique. Raw and surface modified multi-walled carbon nanotubes were observed by transmission electron microscope (TEM). The results showed that chitosan and β-cyclodextrin could attach to the outer surface of nanotubes, wrapping the nanotubes axially. In contrast to the chitosan, β-cyclodextrin not only would attach to the inner and outer surface of the MWCNT walls but also fill their hollow section. It was also found that the surface modified MWCNTs were shorter and their dispersion in organic solvent (NMP) was better than r-MWCNTs. Sedimentation test revealed that dispersion of β-cyclodextrin surface modified MWCNTs was better stabilized in NMP solvent than the chitosan surface modified MWCNTs.

Toluidine Blue O (TBO) is a cationic dye which is extensively used in the industries. In the present paper a simple and efficient wet chemical method was introduced for removal of TBO from waste aqueous solution. Magnetic multi-walled carbon nanotubes were synthesized using commercially available multi-wall carbon nanotubes and magnetic iron oxide nanoparticles which were examined for removal of TBO. The magnetic adsorbents were easily manipulated using an external magnetic field for desired separation, causing the removal of dyes from polluted water. The experimental results revealed that after 30 min, the separation process for TBO absorption reaches to equilibrium at pH 7.0. The optimum condition for removal of TBO was reported.

α-Fe2O3 (hematite) is the most stable iron oxide under ambient conditions. This transition metal oxide has been extensively investigated because it has unique electrical and catalytic properties. In this report, a novel microwave method for preparation of α-Fe2O3 nanoparticles has been developed. The process contained two steps: first, precursor were obtained from a mixed solution of 50 ml of 0.3 M Fe (NO3)2.9H2O and 1.2 g of urea under 540 W microwave irradiated for 6 min. Then, the precursors were calcined at 800 °C to fabricate pure α-Fe2O3 (hematite) nanoparticles for 4 h. Nanoparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Energy dispersive X-ray spectrometer (EDX) technique. The results indicate that the morphologies of final products significantly depend on the reaction conditions including the reaction time, the initial concentration of precursor, reagent and calcinations temperature.

Studies of the magnetization of Fe2O3@Pt nanoparticles at room temperature showed that there is superparamagnetic contribution with high saturation magnetization about 12.35(emu/g), and soft ferromagnetic contribution with narrow coercive field about 58(Oe). In this paper we fitted the hystersis loop of sample with Brillouin function that demonstrating existence of superparamagnetic phase. Total angular momentum quantum number J With computations performance, gave consistent value at high level that could be the reason into existence of spin clusters. Upshot theoretically, magnetic susceptibility of this sample was calculated from the Brillouin function at fields less than 1000(Oe) from 0.1 to 400 K to determine the high-temperature susceptibility.

Copper oxide nanostructures have been successfully synthesized via one-step solid-state thermolysis of two metal-organic frameworks, [Cu3(btc)2] (1) and [Cu(tpa).(dmf)] (2), (btc = benzene-1,3,5-tricarboxylate, tpa = therephtalic acid = 1,4-benzendicarboxylic acid and dmf = dimethyl formamide) under air atmosphere at 400, 500, and 600°C. It has also been found that the reaction temperature plays a substantial role in the formation of copper oxide nanostructures. The obtained products were characterized by X-ray powder diffraction (XRPD), Energy dispersive X-ray microanalysis (EDX), and scanning electron microscopy (SEM). Different reaction conditions were discussed. This study demonstrates that the metal-organic frameworks can be used as precursors for the preparation of nanoscale materials with difference and remarkable morphologies.

Solid solutions of Ag-Cu were prepared via ball milling process, for about 5-30 h. The Cu-20at%Ag and Cu-3.64at%Ag composition were investigated by X-ray diffraction technique. It was realized that the solid solubility level could be increased by increasing the initial solute content in the mixture. In addition, shifts in peak positions of silver and copper were observed with milling time. The dissolution volume was estimated by thermodynamic relations and was compared with the measured values using X-ray diffraction technique and it was observed that the measured and calculated volumes agreed well. The final dissolution volume of 39.155 litters was calculated by thermodynamic relationship.

The present work deals with the synthesis and characterization of CdS nanoparticles with good thermal stability and optical properties by a novel and simple synthetic route. The nanoparticles were synthesized via chemical precipitation method in a single reaction vessel under ambient conditions. The prepared CdS nanoparticles were compared with the bulk CdS. The Optical properties were determined by using UV-Vis spectroscopy. The band gap from Absorption Spectra was found to be 2.66eV (470nm) while that of bulk is 2.42eV (515nm). Thermal properties were determined by DTA, TGA and DTG. The particles show good thermal stability with high melting point (~12500C). Structural and Morphological properties were analyzed by FTIR, XRD, SEM and TEM. The XRD pattern exhibit features of cubic crystal structure having morphology of octahedron and tetragonal phases. The particle size calculated from UV-Vis Spectroscopy, XRD and TEM was well below 10 nm.

This research evaluates the efficiency of nanosized ZnO in the catalytic ozonation of 4-chloro-2-nitrophenol and determines the effect of pH on heterogeneous catalytic ozonation. The combined use of ozone and ZnO catalyst leads to conversion of 98% 4-chloro-2-nitrophenol during 5 min. In addition, it was found that in ZnO catalytic ozonation, the degradation efficiency of 4-chloro-2-nitrophenol was higher at low pH conditions (pH 3.0) than higher pH (pH 7–9). This result was not agreed in the case of ozonation alone, following which higher pH had positive effect on the degradation of 4-chloro-2-nitrophenol. At pH=3, the amount of total organic carbon was 54%. In the degradation of 4-chloro-2-nitrophenol by catalytic ozonation, the high reaction rate constant was obtained in acidic solution.