H. Salehi, P. Amiri, Y. Loveimi Motlagh,
Volume 37, Issue 1 (6-2018)
Abstract
In this article, the electronic and optical properties of bulk TiC and its narrow nanowires were investigated using Quantum-Espresso/PWSCF computational package in the framework of density functional theory. According to the results, this compound showed a metallic behavior in the bulk structure, but the small diameters of the nanowires against the bulk structure showed a semiconducting behavior. This deviation became negligible at the higher diameters. In both structures, the electronic results were compatible with the optical calculations of the structure under consideration. Considering the optical results, the structure of bulk TiC had the maximum amount of refractive index value and this amount could be decreased by a reduction in the nanowire diameters. Also, the optical results indicated that by increasing the size of nanowires, the ELLOS value was raised toward the corresponding bulk value
S. Faraji, Gh. Dini, M. Zahraei,
Volume 37, Issue 1 (6-2018)
Abstract
Manganese ferrite nanoparticles (NPs) have different applications, especially in medical diagnosis and treatment as well as the biomolecule separation,. In this research, the effects of various parameters such as the pH of reaction solution and the hydrothermal process duration on the synthesis of spinel phase in NPs were evaluated. Crystal structure, chemical composition, morphology and size of synthesized particles were investigated by the X-ray diffraction (XRD) analysis and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS). The XRD results showed that the process duration of 12 h and pH=11 were suitable for the formation of monophase manganese ferrite NPs. The FE-SEM investigations showed that the average size of the synthesized NPs was about 50 nm. Moreover, the EDS analysis showed the presence of about 20% of manganese in the NPs structure. Hydrothermally synthesized manganese ferrite NPs in this researchcould be, therefore, a good candidate for the biomedical application due to their small size and narrow size distribution.
Z. Talebi, Mahin Karimi, Negar Habibi,
Volume 37, Issue 1 (6-2018)
Abstract
In the present study, silica aerogel was evaluated by a two-step catalytic process at the ambient pressure drying, under different synthesis conditions. The effects of the catalyst and water content in the hydrolysis step on the physical properties of silica aerogel, including density, porosity and shrinkage, were investigated. The results showed that increasing the water content in the hydrolysis step increased the shrinkage of gel network and density of obtained aerogel. Moreover, in the presence of insufficient water, NH4OH as the condensation catalyst in the gel formation step was more effective on the physical properties of silica aerogel, as compared to HCl as thehydrolysis catalyst; Moreover, the increase in the NH4OH content led to lower density and higher porosity. On the other hand, NH4OH effect on the physical properties of silica aerogel was not noticeable in the presence of enough water content. In the NH4OH/HCl molar ratio of 6, the best silica aerogel sample was obtained with the density of 0.214 g/cm3, porosity of 90% and shrinkage of 23%
Z. Khosroshahi, F. Karimzadeh, M. Kharaziha,
Volume 37, Issue 2 (9-2018)
Abstract
Due to electrical properties (high electron mobility) and electrochemical characteristics (high electron transport rate), graphene-based materials have been widely applied for various scientific fields. However, due to their two-dimensional structures, these materials have low active sites for reaction. Therefore, changing from two-dimensional sheets dimensional to the three-dimensional ones could provide graphene-based materials with high specific surface and electron and mass transport particles. For these purpose, reduced graphene oxide (rGO) and polystyren (PS) aqueous solution were mixed with two different weight ratios kinetic. In this study, the three-dimensional graphene (3DG) was synthesized with graphene oxide using sacrificial PS particles. For this purpose, rGO and the PS aqueous solution were mixed with two different weight ratios of 95:5 and 85:15. Then, the 3DG-PS scaffolds were synthesized by controlling the pH value in the range of 6-8. Subsequently, PS particles were removed by immersing the synthesized scaffolds in toluene. In this research, the effect of filtering through the member filter and centrifuge on the morphology of the scaffolds was investigated. The scaffolds were characterized with X-ray diffraction and scanning electron microscopy. The results showed the formation of 3DG with a uniform distribution of porosities by using the centrifuge procedure. Moreover, the sacrificial PS particles were completely removed when the rGO to PS weight ratio was 95:5. So, 3DG with the uniform distribution of microscopy porosity could be synthesized through the sacrificial mold method and the centrifuge procedure; graphene oxide was also reduced with the PS weight ratio of 95:5. Further, based on the electrochemical evaluation of this optimized sample, as compared to the rGO , it was found that the 3DG had better electrochemical properties than the rGO. Therefore, 3DG with the optimized rGO to PS weight ratio of 95:5 could be an ideal substitute for rGO in electrochemical applications
S. Daneshvar E Asl, S. Kh. Sadrnezhaad,
Volume 37, Issue 2 (9-2018)
Abstract
Rutile-phase titanium dioxide nanorod arrays were prepared by the hydrothermal method. Then, anatase-phase nanoleaves were successfully synthesized on the nanorod arrays via mild aqueous chemistry. Nanorod arrays scanning electron microscopy revealed that the thin film is uniform and crack free and the average diameter and height of the nanorods are 90 nm and 2 µm, respectively. Furthermore, nanorods are vertical to the substrate surface and have desired coverage density due to the predeposition of TiO2 seed layer which leaded to decrease the surface roughness of the substrate. Nanoleafed nanorods scanning electron microscopy indicated that the nanoleaves were grown uniformly on the entire surface of nanorods and the specific surface area and roughness factor of those are significantly improved. Energy dispersive spectrums suggested that F- and Cl- ions are partially doped into TiO2 crystals. Raman and X-ray spectra confirmed the formation of anatase-phase nanoleaves on the rutile-phase nanorods. X-ray diffraction also indicated that the nanorod arrays are highly oriented with respect to the substrate surface. The diffused reflectancetransmittance data revealed the incident light was more efficiently harvested by the nanoleafed nanorod thin film and the values of energy gap are 2.78 and 2.82 eV for rutile TiO2 nanorod and rutile+anatase TiO2 nanoleafed nanorod thin films, respectively. Synthesized nanostructure, having improved charge separation and transfer (due to the presence of the surface anatase/rutile junctions), high specific surface area and light harvesting (due to the presence of the nanoleaves) and low band gap energy (due to the nonmetallic elements doping), is viable alternative to traditional single crystalline TiO2 nanorods for highly efficient photoelectrochemical applications.
G. Pishevarz, H. Erfan Niya, E. Zaminpayma,
Volume 37, Issue 3 (12-2018)
Abstract
Abstract: In this work, the amounts of the adsorption of conjugated polymers onto graphene/ graphene oxide were examined by reactive force-field molecular dynamics simulation. The polymers were poly(3-hexylthiophene) (P3HT) and poly(phenothiazine vinylene-polythiophene)(PTZV-PT). The length and width of the graphene sheet were 95.19 Å and 54.16 Å, respectively. The graphene oxide sheets with different oxidation percentages were considered. The molecular dynamics simulation results demonstrated a higher amount of adsorption onto graphene oxide sheets in comparison to graphene; furthermore, poly(phenothiazine vinylene-polythiophene) revealed a larger amount of adsorption in comparison with poly(3-hexylthiophene) in both functionalized groups of hydroxyl and epoxy. Also, some structural properties of polymers, such as radius of gyration of polymer and radial distribution function, were calculated at different reactive sites.
M. Eshraghi, Z. Mosleh, M. Rahimi,
Volume 38, Issue 1 (6-2019)
Abstract
In this investigation, the structural and magnetic properties of Cr and Zn substituted Co ferrite with the general formula Co1-xZnxFe2-xCrxO4 (x= 0.1, 0.3, 0.5, 0.7) as prepared by sol- gel method were studied. The structural, morphological and magnetic properties of the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM) and Vibrating sample magnetometer (VSM). XRD measurements along with the Rietveld refinement indicated that the prepared samples were single phase with the space group of Fd-3m. Results of SEM images also showed that the particles were in the nanosize range. Also, the magnetic properties of the samples indicated that the magnetization was first decreased, reaching the minimum value for x=0.1 sample; then it was increased. This behavior was related to the cation distribution at the tetrahedral and octahedral sites. Moreover, coercivity was significantly decreased with increasing the doping level due the decrease of magnetocrystalline anisotropy because of the nonmagnetic Zn ion substitution.
A. Jafari, S. Khademi, M. Farahmandjou, A. Darudi, R. Rasuli,
Volume 38, Issue 2 (9-2019)
Abstract
Titanium dioxide nanoparticles (TiO2) are known as a widely used photocatalyst. In order to improve the performance of these nanoparticles, the recombination of the electron-cavity pair must be reduced and the absorption rate of the visible region should be expanded. One way to increase the performance of these nanoparticles is using cerium doped TiO2. In the present study, pure and doped titanium dioxide nanoparticles were made by the electrical discharge method. The effect of cerium dopants on the structural, morphological and optical properties were studied by x-ray diffraction (XRD), scanning electron microscopy (FESEM), diffused reflection spectroscopy (DRS), photoluminescence (PL) and infrared fourier transform (FTIR) spectroscopy analyses. XRD analysis revealed that the size of TiO2 nanocrystals was decreased to 7.7 nm. The FESEM morphology of the samples also showed that the uniformity of the Ce doped TiO2 was decreased. Further, the DRS results indicated that the band gap energy of Ce-TiO2 was decreased to 2.24 eV. The photoluminescence results demonstrated that the intensity of PL was reduced for the Ce-TiO2 sample, which reduced the recombination of the electron-hole coupling and increased the photocatalytic activity in the doped sample.
F. Mohammadi Bodaghabadi, M. R. Loghman Estarki, M. Ramazani, A. Alhaji,
Volume 38, Issue 3 (12-2019)
Abstract
In this research, synthesis of lithium fluoride (LiF) nanoparticles by fluorolytic sol-gel method has been studied. Moreover, the effect of lithium ion to fluorine source molar ratio and calcination temperature on particle size and phase of LiF nanoparticles were investigated. Lithium acetate (C2H3LiO2), trifluoroacetic acid (TFA), ethylene glycol monobutyl ether and oleic acid were used as sources of Li+ and F- ions, solvent and growth inhibitor, respectively. Thermal and X-ray diffraction (XRD) analyses as well as field emission scanning electron microscopy (FESEM) were used to investigate thermal behavior of the primary gel and to determine the phase and morphology of samples, respectively. The results showed that the 2: 1 molar ratio of Li+/ TFA and the calcination temperature of 400 °C result in LiF nanoparticles with a mean particle size of 80-100 nm.
N. Poursharifi, D. Semnani, P. Soltani, S. Amanpour,
Volume 38, Issue 4 (1-2020)
Abstract
In this study, seven-layer nanofiber structures consisting of polycaprolactone/ chitosan polymers loaded with methotrexate and 5-fluorouracil anti-cancer drugs, for controlled drug delivery, were produced and evaluated. For this purpose, the second, fourth and sixth layers were loaded with drug and placed between the drug-free layers. The surface morphology of drug-free and drug-loaded nanofibers was investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR) was used to study their chemical structure. The drug release rate in phosphate buffered saline (pH=7.4) and the released drug concentration were measured by spectrophotometry. Mechanical properties of single- and multi-layered samples were also investigated. SEM images showed formation of uniform and beadless fibers. FTIR spectrum confirmed presence of the drugs in the polymer mixture with no interaction. It was found that by increasing the chitosan content, a brittle structure with decreased elongation is formed. The release behavior of methotrexate and 5-Fluoracil drugs in neutral pH environment for 26 days was evaluated and the results exhibited a slow and sustained release.
M. Shirvani, M. Mashhadi, M. Yosofi,
Volume 38, Issue 4 (1-2020)
Abstract
In this research, solid state carbothermal synthesis of HfB2 Nano powders was investigated. For this purpose, HfO2,H3BO3, carbon active or phenolic resin were used as raw materials for carbothermal reaction. After 2-4 hours of milling the raw materials by a planetary ball in an ethanol media, the mixture was heat dried and pressed in to disks under pressure of 20-30 bar. The disks were then placed in a graphite crucible and heat-treated at 1500–1600 °C for 1 hour under flowing Ar atmosphere. The powder product was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and backscattered electron (BSE) imaging. The heat treatment temperature, amount of boric acid, milling and heat treatment time were recognized as four factors influencing synthesis and size of HfB2 powder particles. SEM images reported irregular morphologies with a particle size of about 2-4 µm for HfB2 powder. The best sample was obtained at a molar ratio of HfO2 : phenolic resin carbon: boric acid = 1:5:5 at 1600 °C after 1 hour of heat treatment. XRD results confirmed synthesis of pure HfB2 with a crystallite size of about 60 nm.
M. Mahallati, M. Khosravi,
Volume 39, Issue 2 (8-2020)
Abstract
In this research, using phenolic resin as the precursor of carbon and various amounts of ethylene glycol as a pore former, porous samples of hard carbon were synthesized. Samples were characterized by x-ray diffraction (XRD) and N2 adsorption-desorption methods. Broad diffraction peaks represent the amorphous structure of samples. Moreover, the gas adsorption-desorption curves showed that the adsorption isotherms of samples were of type IV and all samples had meso-micro porous structure. Charge-discharge tests were performed on samples to obtain their capacities. The sample with higher capacity, broader XRD pattern and appropriate porosity, was selected for silicon incorporation. Silicon nanoparticles were obtained by mechanical milling of its micro particles. According to XRD patterns, silicon nanoparticles had a crystalline structure. Field emission scanning electron microscopy (FESEM) images approved uniform distribution of nanoparticles. XRD patterns of nanocomposites evidenced the existence of hard carbon and silicon. The electrochemical test results showed that the capacity, coulombic efficiency and cycle life of nanocomposites were improved by increasing the amount of silicon.
A. H. Kianfar, N. Eskandari, M. A. Arayesh,
Volume 39, Issue 2 (8-2020)
Abstract
In this research the synthesis of [Co(Salen)(PPh3)(H2O)]4[Fe(CN)6] and [Co(Salophen)(PPh3)(H2O)]4[Fe(CN)6] schiff base complexes was reported. Co3O4/CoFe2O4 magnetic nanoparticles were prepared by calcination of these complexes at 500, 550 and 600°C. Precursor complexes were identified by FT-IR and UV-Vis spectroscopy and their thermal behavior was studied via TG/DTA. Nanomagnetic samples were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FT-IR). Magnetic properties of the synthesized nanoparticles were studied using Vibrating Sample Magnetometer (VSM). Magnetic parameters such as saturation magnetization (Ms), remanent magnetization (Mr), coercive field (Hc) and squareness ratio (SQ = Mr/Ms) were determined at room temperature. Stoichiometry and approximate composition of the prepared samples were studied by Electron Diffraction X-ray spectroscopy (EDX). The prepared nanocomposites could be useful in some practical applications due to their high magnetization, good chemical stability and dispersion.
T. Rajabi, M. Vahedi, S. K. Sadrnezhaad,
Volume 39, Issue 2 (8-2020)
Abstract
Zinc/zinc oxide nanoparticles are used in an increasing number of medical and industrial applications due to their attractive physical, chemical and antibacterial properties. Therefore, achieving a simple and beneficial way to produce them is an important aspect. In this study, zinc/zinc oxide nanopowders were synthesized by fast electric discharges between two electrodes of (a) a spark device in distilled water medium and (b) a handmade high-voltage ignition machine in argon gas medium. The resulting powders were characterized by x-ray diffraction (XRD), dynamic light scattering (DLS) and field emission electron microscopy (FESEM). Using the spark device in distilled water, a mixture of zinc crystals with an average diameter of 11.28 nm and zinc oxide crystals with an average diameter of 22.22 nm was produced. However, using the handmade device in argon, zinc crystals with an average diameter of 7.5 nm were obtained and subsequently oxidized due to their extremely high activity. The production rate of the high voltage discharge method was lower than other conventional methods. On the other hand, its ability in reducing the size and increasing the particle activity was higher than other methods.
H. R. Karimi, H. Mansouri, M. R. Loghman Estarki, M. Tavoosi , H. Jamali,
Volume 40, Issue 1 (5-2021)
Abstract
This study aimed to compare the phase changes and morphology of yttria-stabilized zirconium oxide powders (YSZ) synthesized by co-precipitation and molten salt methods. Ammonia precipitating agent was used for the synthesis of YSZ powder by co-precipitation method and a mixture of sodium carbonate and potassium carbonate salts was used as a molten salt in the molten salt method. Samples were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC) analysis. The results showed that only the sample prepared with zirconium oxychloride and yttrium nitrate by co-precipitation method had a single phase of yttria-stabilized zirconium oxide with tetragonal crystal lattice and particle size distribution in the range of 30 to 55 nm. The powder synthesized by the molten salt method contained a mixture of zirconia with monoclinic crystal lattice and yttria stabilized zirconia with tetragonal crystal lattice and particle size of 200 nm.
M. Shayestefar, A. R. Mashreghi, S. Hasani ,
Volume 40, Issue 1 (5-2021)
Abstract
Mn0.8Zn0.2Fe2-xDyxO4 (where x= 0, 0.025, 0.05, 0.075, 0.1) ferrite nanoparticles were synthesized by auto- combustion sol-gel method for the first time in this study. The effect of Dy-doping on the structural and magnetic properties of the produced specimens was examined using the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometery (VSM), and field emission scanning electron microscope (FE-SEM). The results showed that a cubic spinel structure was formed in all of the synthesized specimens. It was also found that the addition of Dy increased the lattice parameter while decreased the average of crystallites size. Furthermore, the FE-SEM micrographs showed that Dy not only plays an effective role in reducing the agglomeration of nanoparticles and their distribution, but also reduces the average of particle size. It was also observed that the addition of Dy had no effect on the morphology of the synthesized nanoparticles. Investigation of the magnetic properties revealed a clear decrease in the saturation magnetization and coercivity by the Dy addition. So that the saturation magnetization of the samples decreased from 66.3 to 58.4 emu/g and the coercivity decreased from 78.5 to 71.9 Oe.
R. Karimi-Chaleshtori, M. R. Saeri, A. Doostmohammadi ,
Volume 40, Issue 1 (5-2021)
Abstract
Silver nanowires (AgNWs) are considered as one-dimensional nanostructures, which have received much attention due to their nanoscale size, high aspect ratio, high electrical and thermal conductivity, optical transparency and high mechanical stability. Preparation of AgNWs by polyol process is remarkably sensitive to the interactions between synthesis parameters. In this study, the effect of the simultaneous change of four synthetic parameters, namely the reaction temperature, the molecular weight of polyvinylpyrrolidone (PVP) stabilizer, the amount of sodium chloride, as well as, the solution mixing rate by the polyol process was reported. The results of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) confirmed that the synthesized AgNWs were below 100 nm. X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, as well as, Fourier transform infrared spectroscopy (FT-IR) confirmed that the formed AgNWs were free of impurities. It was also found that temperature, molecular weight of PVP, salt concentration and solution mixing rate caused a significant change in the morphology of AgNWs. More importantly, a strong interaction was created in the preparation process of AgNWs by adjusting the parameters.
F. Delshad, M. Maghrebi, M. Baniadam,
Volume 40, Issue 2 (9-2021)
Abstract
Carbon nanotubes contain impurities and deamorphization is one of the methods of their purification. In this study, for the first time, a solution of piranha with a ratio of 3:1 (30 ml sulfuric acid + 10 ml hydrogen peroxide) as well as microwave irradiation with processing time of 30 minutes were used to remove amorphous carbon from the nanotube arrays. Ultrasonication was performed to disperse pristine and purified carbon nanotubes in water and centrifugation was performed to separate large particles. To assess the removal of amorphous carbon, new characterization methods such as dispersed percent and floating percent were used. It was observed that with increase in the ultrasonication time (from 0 to 50 minutes), the dispersed percentage of treated arrays was increased (about 47%), while the floating percentage of pure array decreased (about 20%). These results are ascribed to the removal of amorphous carbon. The results of the thermo gravimetric analysis (TGA) were in good agreement with the results obtained from the newly proposed characterization methods.
R. Bagheri, F. Karimzadeh, A. Kermanpur , M. Kharaziha,
Volume 40, Issue 2 (9-2021)
Abstract
A new method has been presented for the synthesis of copper (Cu)/copper oxide (CuO)-nanoparticles (NPs), based on the process of corrosion and oxidation of Cu-NPs on the surface of the gold electrode by nitric acid. Cu-NPs were deposited on the surface using potentiometric method. The high concentration of Cu-NPs was estimated by Differential Pulse Voltammetry (DPV). The process of growth and distribution of CuO-NPs on the surface of Cu-NPs using structural analysis of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) showed that nitrate was well absorbed and a sharp hydroxyl peak appeared and a phase of CuO NPs formed on the electrode surface. The surface morphology indicated that the average size reduced from about 150 nm to 50 nm in the presence of nitrate. This can be due to the oxidation of Cu nanoparticles on the surface and reduction of particle size compared to the absence of nitric acid. This simple and low-cost method can be used as a surface modification of antibacterial and active catalyst electrodes.
A. Azimi-Fouladi , S.a. Hasanzadeh-Tabrizi,
Volume 41, Issue 2 (11-2022)
Abstract
Water pollution is one of the big problems of human societies, and the need to find new ways to remove these pollutants has been given much attention in recent years. One of the methods is the use of photocatalysts. In this research, TiO2 and TiO2-CdO nanoparticles were prepared by a sol-gel method as nano photocatalysts. The produced samples have been used to degrade methylene blue under UV light. To characterize the prepared samples, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), X-ray Energy Diffraction Spectroscopy (EDS), and Ultraviolet-Visible Spectroscopy (UV-Vis) were used. Microstructural results revealed nanoparticles with dimensions of 18 to 32 nm. XRD results showed that the main phase formed was the anatase. TiO2-4 wt.% CdO nanocomposite showed more photocatalytic activity compared to pure TiO2. Also, the effect of pH, irradiation time, and amount of powder on photocatalytic activity was investigated. The results showed that at pH=9, time of 75 min, and using 0.02 g TiO2-4 wt.% CdO photocatalyst, the maximum photocatalytic activity of about 92 % was obtained.
