فهرست مطالب

Bio-Inorganic Hybrid Nanomaterials - Volume:1 Issue: 4, winter 2013

International Journal Of Bio-Inorganic Hybrid Nanomaterials
Volume:1 Issue: 4, winter 2013

  • تاریخ انتشار: 1391/12/20
  • تعداد عناوین: 8
|
  • Mirabdullah Seyedsadjadi, Parissa Mashayekhi Pages 209-214
    In this work, we report synthesis and characterization of copper nanoparticles in polymer matrix by wet-chemical reduction method using ascorbic acid as reducing agent, copper (II) sulfate as metal precursor and polyvinylpyrrolidone k-30 (PVP K-30) as surfactant agent. The reaction was carried out in a high-speed stirring mixture at room temperature under nitrogen atmosphere. Characterization of the samples was carried by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis. The results indicated that, the molar ratio of precursor to surfactant plays a crucial role in the homogeneous growth of copper nanoparticles aggregates and the best condition for formation of homogeneous copper nanoparticles aggregates in polymer matrix was provided for a molar ratio of precursor to surfactant, CuSO4.5H2O/PVP= 70/1 using ascorbic acid as reducing agent. The average particle size of zero valence Cu NPs calculated using Scherrer's formula was about 7.9 nm.
    Keywords: Polyvinylpyrrolidone, Ascorbic acid, Copper nanoparticles, Wet chemistry method
  • Sang Woo Joo, Younes Hanifehpour, Bong, Ki Min Pages 215-226
    Lu3+/Yb3+ and Lu3+/Er3+ Co-doped Sb2Se3 nanomaterials were synthesized by a Co-reduction method in hydrothermal condition. Powder XRD patterns indicate that the LnxLn′xSb2-2xSe3 Ln: Lu3+/Yb3+ and Lu3+/Er3+ crystals (x= 0.00-0.04) are isostructural with Sb2Se3. The cell parameters were increased for compounds upon increasing the dopant content (x). SEM and TEM images show that Co-doping of Lu3+/Yb3+ ions in the lattice of Sb2Se3 results in nanorods while that in Lu3+/Er3+ leads to nanoparticles, respectively. The electrical conductivity of Co-doped Sb2Se3 is higher than the pure Sb2Se3, and increases with temperature. By increasing concentration of Ln3+ ions, the absorption spectrum of Sb2Se3 shows red shifts and someintensity changes. In addition to the characteristic red emission peaks of Sb2Se3, emission spectra of Co-doped materials show other emission bands originating from f-f transitions of the Yb3+ ions.
    Keywords: Co, doped, Nanomaterial, Luminescent, Electrical conductivity
  • Homayon Ahmad Panahi, Paria Pouyan, Ava Shahrokhzadeh, Elham Moniri Pages 227-231
    Poly urea-formaldehyde was synthesized simply and rapidly from urea and formaldehyde by condensation polymerization and studied for the sorption of trace acid blue from aqueous solution. The optimum pH value for sorption of the acid blue was 4. Experimental results showed that the sorption capacity of poly urea-formaldehyde for acid blue was determined. The synthetic polymer can be reused for 5 cycles of sorption-desorption without any significant change in sorption capacity. The equilibrium adsorption data of acid blue on poly urea-formaldehyde were analyzed by Langmuir models. Based on equilibrium adsorption data the Langmuir constants were determined about 19 L.mg-1 at pH 4 and 20°C.
    Keywords: Polymer urea, formaldehyde, Acid blue, Isotherm study, Sorption, Textile dye, Contaminant
  • Meysam Mazhdi, Faramarz Torkzadeh, Faezeh Mazhdi Pages 233-241
    ZnO and ZnO: Mn nanocrystals synthesized via reverse micelle method. The structural properties nanocrystals were investigated by XRD and Transmission electron microscopy (TEM). The XRD results indicate that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. The various optical properties of these nanocrystals such as optical band gap energy, refractive index, dielectric constants and optical conductivity have been analyzed by using UV-Vis data. The refractive index decreases from 2.35 to 1.35 with the change of wavelength. The optical conductivity supports the accuracy of our energy band gap calculation. Room-temperature photoluminescence spectra of all the samples showed four main emission bands including a strong UV emission band, a weak blue band, a week blue-green band, and a weak green band which indicated their high structural and optical quality. Moreover the samples exposed to Gama rays sources of 137Cs and 60Co and their thermoluminescence properties were investigated. Their thermoluminescence response as a function of dose exhibited good linear ranges, which make them very promising detectors and dosimeters suitable for ionizing radiation.
    Keywords: ZnO, Reverse micelle, UV, Vis Spectroscopy, Optical properties, Photoluminescence, Thermoluminescence, Nuclear radiation detection
  • Fatemeh Azarakhshi, Nazanin Farhadyar Pages 243-252
    NBO analysis, hybrid density functional theory (B3LYP/6-311+G**) and ab initio molecular orbital (HF/6-311+G**) based methods were used to study the anomeric effects (AE), electrostatic interactions, dipole-dipole interactions and steric repulsion effects on the conformational properties of 2-methoxy- (1), 2-methylthio- (2), 2-methylseleno- (3), 2-fluoro- (4), 2-chloro- (5) and 2-bromocyclohexane-1,3-dione (6). The B3LYP/6-311+G** and HF/6-311+G** results indicates the axial preference in these compounds. The methods used show that these compounds exist predominantly in the axial chair conformation and the axial conformation stability and calculated Gibbs free energy difference (ΔGeq-ax) values between the axial and equatorial conformations increase from 1 to its analogous 3 and also from 4 to its analogues 6. The NBO analysis of donor-acceptor interactions show that the GAE (Generalized Anomeric Effect) increases from compound 1 to compound 3 and also from compound 4 to compound 6. GE (Gauche Effect) does not have significant impact on the conformational behaviors of compounds that have been studied and GAE succeeds in accounting qualitatively for the increase of the axial preferences. On the other hand, the calculated differences between the dipole moment values of the axial and equatorial conformations, Δ(μeq-μax), are not in the same trend observed for the corresponding GAE and ΔG values. These findings led to the proposal that the calculated GAE values due to donor→acceptor hyperconjugation effects are more significant for the explanation of the conformational preferences of compounds that have been studied than the electrostatic interactions. Also similar results are obtained for their analogous containing S and Se atoms. The correlations between the GAE, GE, dipole-dipole interactions, donor and acceptor orbital energies and occupancies, bond orders, structural parameters and conformational behavior of compounds (1-6) and their analogous containing S and Se atoms have been investigated.
    Keywords: Stereoelectronic interactions, Generalized Anomeric Effects, Ab initio, NBO, 2, Substituted cyclohexane, 1, 3, diones
  • Masoumeh Tabatabaee, Naser Saberi Pages 253-256
    Nano-sized γ-Al2O3 was synthesized successfully by a simple method using Al2(SO4)3·5H2O as aluminium source and in the presence of polyethylene glycol (PEG 2000). FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize the structure and morphology of synthesized powder. The results showed that PEG played a significant role in the decomposition of aluminum nitrate to γ-aluminum oxide nanoparticles with a size range of 10-15 nm. The experimental results showed that polyethylene glycol can avoid hard agglomerate during precipitation and that calcination temperature was the major factor to particles size of the final product and it played a significant role in the decomposition of aluminum nitrate to γ-aluminum oxide nanoparticles with a size range of 10-15 nm.
    Keywords: Nanoparticles, γ Alumina, Hydrothermal synthesis, Polyethylene glycol, Particles size, X-ray diffraction
  • Mir Hasan Hosseini, Meysam Sadeghi Pages 257-263
    Pure and ZnO-doped Ni0.1Co0.9Fe2O4 catalyst were prepared by co-precipitation method and thermal decomposition in air calcinated at 400-700°C and that treated with different amounts of zinc nitrate (0.46-2.25 w% ZnO). X-ray powder diffractometry, scanning electron microscopy (SEM) and BET analysis of nitrogen adsorption isotherms investigated the crystalline bulk structure and the surface area of pure and doped samples, respectively. The hydrogen peroxide decomposition activity was determined by oxygen gasometry of the reaction kinetics at 20-40°C. The results revealed that the treatment of Ni0.1Co0.9Fe2O4 with ZnO at 400-700°C brought about a significant increase in the specific surface area and catalytic activity of Ni0.1Co0.9Fe2O4 on decomposition of hydrogen peroxide. However, the catalytic activity of H2O2 decomposition on Ni0.1Co0.9Fe2O4 calcined at different temperatures was found to show a considerable increase by doping with ZnO. They were discussed with UV/VIS spectroscopy which the energy band gap of the synthesized Ni0.1Co0.9Fe2O4 nano structure was calculated to be ~5 eV.
    Keywords: Nickel cobalt ferrite, Nanoparticles, Catalytic activity, Decomposition of hydrogen peroxide, Calcination temperature, Promoter, Optical characterization
  • Elmira Amani, Kaykhosrow Khojier, Naser Zare Pages 265-270
    ZnO thin films were deposited on Si(400) substrates by e-beam evaporation technique, and then post-annealed at different annealing temperatures (200-800°C). Dependence of the crystallographic structure, nano-strain, chemical composition and surface physical Morphology of these layers on annealing temperature were studied. The crystallographic structure of films was studied using X-Ray Diffraction (XRD) method, while the chemical composition and surface morphology of layers were investigated by Field Emission Scanning Electron Microscopy (FESEM). The XRD results showed that ZnO (002) crystallographic orientation was a preferred orientation for growth of ZnO thin films. Increasing of annealing temperature caused increasing of intensity and decreasing of FWHM for ZnO (002) peak and decreasing of dislocation density in the films. The nano-structural investigations also showed that mentioned peak position and nano-strain were varied with increasing of annealing temperature. Chemical composition analysis showed that the ratio of oxygen to Zinc increased with increasing of annealing temperature. SEM images showed a mixed structure of nanowires and nanosheets for annealed films at 350 and 500°C, and a granular structure for annealed samples at 200 and 800°C. However, the annealed films at the highest temperature (800°C) had a dense structure and larger grains than the annealed film at 200°C temperature.
    Keywords: ZnO, Thin films, Crystallographic structure, Nano, strain, Dislocation density, Morphology