جستجوی مقالات مرتبط با کلیدواژه "superparamagnetic" در نشریات گروه "مواد و متالورژی"

We prepared samples including nanoparticles of Fe3O4 via co-precipitation method with microwave heating using water and ethylene glycol as solvent. The procedure was repeated with various natural surfactants. XRD and SEM analysis was performed to determine the nanostructural characteristics of nanoparticles. SEM analysis disclosed that the type of surfactant and solvent will affect the nanostructures. In the next stage, Fe3O4/Ag nanocomposite was prepared using magnetite nanoparticles and AgNO3 by microwave method and its nanostructure was defined by SEM and TEM analysis. The mean diameter was determined between 40-55 nm from SEM software and 44-64 nm by Motic software for particles of all samples. Likewise, the purity of Fe3O4 nanoparticles and prepared nanocomposite were documented by FT-IR spectrometry. All the products had pure nanoparticles of Ag and Fe3O4 which was agreed with XRD results. To evaluate the magnetic parameters of samples, VSM analysis were done. Hysteresis curves disclosed that all the products have superparamagnetic properties. We also assessed the photocatalytic potential of prepared nanocomposites using methyl orange and congo red solutions under UV radiation and the effect of concentration of absorbent, pH of solutions and the time of irradiation on the color removing was investigated. This study confirms that these Fe3O4/Ag nanocomposites can be used as recyclable photo-catalysts for water refinery in home and industries. The best result for color removing was for 0.9 gr/lit absorbent, pH=2 and t= 80 min for irradiation.

Reduced graphene oxide coated with zinc ferrite (ZnFe2O4@rGO) nanocomposite was successfully synthesized by the one-step hydrothermal (HT) and the two-step sol-gel/hydrothermal (SG/HT) methods. The results of SEM and TEM images showed that the graphene oxide sheets for HT and SG/HT syntheses had dimensions of 0.3-0.04 μm and 0.7-0.07 μm, respectively,. According to these images, the size of ZnFe2O4 nanoparticles coted on graphene oxide sheets for HT and SG/HT syntheses were observed at 10-40 nm and 25-70 nm, respectively. Comparison of the optical absorption spectrum of ZnFe2O4@rGO nanocomposites synthesized by HT and SG/HT methods revealed that the amount of band gap energy in SG/HT synthesis was about 7% less than from SG/HT synthesis. According to the results obtained from the Raman spectrum for the synthesized graphene oxide sample, the ID/IG ratio was 0.88,. The results of FTIR spectra demonstrated effective reduction of GO as well as composite formation between rGO plates and ZnFe2O4 nanoparticles for both SG/HT and HT synthesis methods. The results of the magnetic properties of ZnFe2O4@rGO nanocomposites synthesized by HT and SG/HT methods by VSM and magnet with 1 T intensity, states that both methods of synthesis produced superparamagnetic materials,. Based on the results of this study, it can be said that for photothermal therapeutic applications which particle size and uniformity of ZnFe2O4@rGO nanocomposites are important, single-step HT method, and for photocatalytic applications and contrast agent in MRI, which need more photocatalytic and magnetic properties, the two-step SG/HT method can be better choice.