جستجوی مقالات مرتبط با کلیدواژه « nanoparticles » در نشریات گروه « مواد و متالورژی »

Copper oxide is obtained by various methods, including electrolysis, recovery of copper salts or copper oxide, thermal oxidation and hydrothermal treatment. Electrochemical method is very interesting due to its low cost, low temperature, ease of operation, high purity and compatibility with the environment. In this research, the effects of NaCl, Na2SO4 and CTAB (cetyltrimethylammonium bromide, C19H42BrN) electrolytes on the synthesis of Cu2O nanoparticles by electrochemical method were investigated. Changes of NaCl in three values of 58.5, 117 and 175.5 (g/lit); changes of Na2SO4 in concentrations of 24, 32 and 48 (g/lit) and changes of CTAB in the range of 2, 4, 6 and 15 (g/lit) were selected. The current density and temperature were fixed and equal to 0.4 (amps/cm2) and 70°C, respectively, and the fixed distance between the cathode and the anode was considered to be 2.5 cm. FESEM and XRD were used to observe the morphology of the samples and identify the composition and determine the particle size. The results showed that by increasing the concentration of NaCl and Na2SO4 electrolyte, the purity of Cu2O increased. The size of Cu2O crystals was below 100 nm and the formation of Cu2O was polycrystalline. Also, high concentration of NaCl gave better results compared to Na2SO4. CTAB effectively prevents the growth of Cu2O nanoparticles and the particle size was inversely related to the increase of CTAB. The best result was obtained in the sample with 4 (g/lit) CTAB and 175(g/lit)NaCl. Cu2O nanoparticles with high purity and crystal size of 27.87 nm were produced.

Iron oxide nanoparticles have been gaining much attention lately due to their magnetic properties and biocompatibility. This research focused on investigating the properties and synthesis of iron oxide nanoparticles that have been substituted with zinc ZnxFe3-xO4 (x= 0.0, 0.2, 0.4, 0.6)  using the hydrothermal method. The synthesized samples were analyzed using X-ray diffraction and found that they have a space group of fd3m. The crystal size of the samples was found to be smaller than 20 nm. Vibrating sample magnetic analysis (VSM) was used to determine the magnetic behavior of the nanoparticles. The analysis showed that the nanoparticles exhibited superparamagnetism. In addition, the saturation magnetization values of the nanoparticles for samples with x = 0, 0.2, 0.4, and 0.6 were 44.10, 49.09, 43.51, and 48.07 emu/g, respectively. The microstructure and grain size of magnetic nanoparticles were analyzed using a field emission electron microscope (FESEM). The FESEM images revealed that the majority of the grains are spherical and have uniform distribution. The average grain size for the sample ranges between 10 and 30 nm. Based on these results, it can be concluded that these particles are suitable for use in medical and catalytic applications.

In recent years, there has been a significant interest in lanthanum-based perovskites due . Lanthanum strontium manganite (LSMO) is one of the most well-known materials. In this research, the synthesis and investigation of the effect of oleic acid on the structural and magnetic properties of La0.7Sr0.3MnO3 nanoparticles by the combustion sol-gel method is discussed. The structural and magnetic properties of the prepared samples were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), magnetic properties analysis (VSM), and field emission electron microscopy (FESEM). In the XRD study, it was found that the crystal structure of the samples is hexagonal. Also, the average crystal size in the samples increased from 18 nm to about 33 nm as a result of adding oleic acid. The images obtained from FESEM show that the presence of oleic acid in the synthesis of nanoparticles caused it to affect the shape of the particles as a surface layer. Synthesized nanoparticles have a particle size between 20-100 nm, and with the increase of oleic acid, the particle size becomes more than 100 nm. FTIR spectroscopy revealed the effective bonding between LSMO nanoparticles and oleic acid, based on these results, it clearly shows the presence of oleic acid molecules on the surface of magnetic particles. In the investigation of magnetic properties, it was found that the presence of non-magnetic sodium oleate surface layer, which due to the addition of oleic acid on nanoparticles, the saturation magnetization value decreased from 38.55 emu/g to 28.46 emu/g.

Nanoparticles have brought significant advantages in a wide range of fields due to their unique size-dependent physical and chemical properties. In this research, the combustion solution method is used to make La0.7Sr0.3MnO3 (LSMO) nanoparticles. Then the nanoparticles are covered with polyethylene glycol polymer. Due to the presence of hydrophilic molecular chains and high flexibility, polyethylene glycol is one of the most ideal coating agents to increase the colloidal stability and biocompatibility of LSMO nanoparticles. Using X-ray diffraction (XRD), the crystal structure, nanoparticle size and nanoparticle composition of LSMO were investigated, and a hexagonal structure with a crystal size of 18.4 nm was observed. Field emission electron microscopy (FESEM) was used to investigate the shape and size distribution of nanoparticles. The images showed that most of the grains are spherical with uniform distribution and the grain size in the processed sample is between 20 and 60 nm. The behavior of nanoparticles was estimated as ferromagnetic using Vibrating Sample Magnetic Analysis (VSM) and the saturation magnetization value before and after nanoparticle coating is 24.8 (emu/g) and 23.6 (emu/g), respectively. FTIR spectroscopy showed effective bonding between LSMO nanoparticles before and after treatment with polyethylene glycol.

In this study, we employed the active TIG method with ultrasonic vibration (UV) for welding 316L steel. Throughout the active tungsten inert gas (A-TIG) welding process, a high-frequency ultrasonic generator produced high-intensity acoustic waves at an optimal frequency of 20.3 kHz and a vibration amplitude of 8 micrometers. These waves were directed into the molten weld pool, covered by SiO2 nanoparticles serving as an activating flux. The effect of UV and nanoparticles on weld geometry and weld microstructure was analyzed and compared with conventional TIG welding proces. The results indicated that the use of nanopowder not only increased weld penetration by approximately 17.5% but also reduced the Weld Bead Width (WBW) by 28% compared to Conventional TIG. These values increased by 25% and decreased by 35%, respectively, in the presence of ultrasonic waves. Additionally, the introduction of nanomaterials into the molten pool led to finer grains. The ultrasonic waves played a crucial role in ensuring the uniform distribution of these nanomaterials in the melt, ultimately resulting in an enhanced microstructure of the weld.

Lanthanum strontium manganese oxide (LSMO) nanoparticles, which have shown favorable magnetic properties, have recently been introduced as a new class of magnetic nanoparticles in the hyperthermia application. The purpose of this study is to look into the behavior of nanocrystalline La0.7Sr0.3MnO3 (LSMO) synthesized by the combustion solution method at various temperatures. Glycine, which acts as a fuel and complexing agent, has been used in this synthesis. LSMO nanocrystals were calcined at different temperatures of 600-1000 °C. The produced LSMO nanocrystals were examined in terms of structural and magnetic characteristics. Based on X-ray diffraction (XRD) study, the crystallite size of LSMO nanocrystals at temperatures of 600, 700, 800, 900, and 1000 degrees Celsius will be 16.6, 9.2, 18.4, 13.8, and 33.2, respectively. The (M-H) curve investigated the magnetic characteristics of LSMO nanocrystals at various temperatures, revealing that the saturation magnetization value at 700 and 900°C temperatures is lower than at 600 and 800°C temperatures, possibly explaining the reduction in nanocrystal size. The effective bonding of LSMO nanocrystals were examined using Fourier transform infrared spectroscopy (FTIR). A field emission electron microscope (FESEM) was used to examine the shape and size distribution of nanocrystals. The micrographs suggested that the particle size range was 20-60 nm.

In this paper, three-types of metal-cations doped superparamagnetic iron oxide nanoparticles (IONs) including glucose-grafted Zn2+-doped MNPs (glucose/Zn-IONs), sucrose-grafted Zn2+-doped IONs (sucrose/Zn-IONs) and starch-grafted Zn2+-doped IONs (starch/Zn-IONs) are reported. These IONs are fabricated by OH– ions electrochemical generation through cathodic deposition method. The saccharide capped layer onto the surface of deposited IONs and also zinc cations doping into their crystal structure were confirmed via Fourier-transform infrared spectroscopy, Field-emission scanning electron microscopy and Energy Dispersive X-ray techniques. Figures of the Field-emission scanning electron microscopy showed that the morphology of particles synthesized is spherical. Analyses revealed magnetite crystal structure with about 10% doped zinc for all the prepared samples. The magnetic evaluations by sample vibrating magnetometer (VSM) technique specified the superparamagnetic behaviors for the prepared samples, where low coercivity and remanence values (i.e. Hci=8.9Oe and Mr=0.24 emu/g for glucose/Zn- IONs; Hci=3.6Oe and Mr=0.09 emu/g for sucrose/Zn- IONs; Hci=9.2Oe and Mr=0.28 emu/g for starch/Zn- IONs) were observed.

The aim of this study was to prepare titanium dioxide nanoparticles calcined at different temperatures to be used for adsorption of zinc ions from aqueous medium and then to investigate the kinetics and isotherms of the adsorption process. For this purpose, nanoparticles were synthesized using the sol-gel method and then calcinated at 450 °C and 800 °C. XRD, BET, FTIR, and SEM analyses were used to investigate the structural, surface, and chemical properties of the synthesized nanoparticles. Adsorption studies revealed that the solution containing zinc with an initial concentration of 10 mg/l had the highest adsorption efficiency under conditions of pH = 7, adsorbent concentration of 0.3 g/l, and temperature of 25 ° C. Under these conditions, adsorbents prepared at 450 °C and 800 °C achieved 99% and 92% adsorption efficiencies, respectively. Adsorption isotherm studies revealed that the Freundlich, Temkin, Langmuir, and Dubinin–Radushkevich isotherms had the best agreement with equilibrium sorption data, in that order. In addition, investigations on fitting into kinetic models revealed that the quasi-second-order, Elovich and the quasi-first-order equations had the best fit with experimental data, respectively.

In this study, magnetic nanoparticles of MnFe2O4@SiO2 activated with N-phosphonomethyl amino di-acetic acid were synthesized with a core-shell structure. Moreover, the characteristics of surface functional groups, crystal structure, magnetic properties, size and surface morphology of these nanoparticles were investigated by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), microscope Scanning electrons (FESEM, Thermal Weight Analysis (TGA) and vibrating sample magnetometer(VSM). In this study, the antiscalant effect of precipitation for magnetic nanoparticles MnFe2O4@SiO2 were examined according to the reference test (NACE TM0374) by using 5 ppm MnFe2O4@SiO2. In this experiment, the precipitation effect of calcium sulfate and calcium carbonate on the surface of carbon steel was investigated. For this purpose, in one test a piece of carbon steel is placed in the presence of the precipitative compound and absence of antiscalant (control test) and in the other test of carbon steel is placed in precipitative compound with the antiscalant (main test) for a certain period of time. Afterwards, the amount of precipitation of the control and main experiment for carbon steel in the similar environment of the cooling tower of thermal power plants containing 1000 ppm sulfate and 500 ppm chloride were investigated. The tafel polarization test and impedance spectroscopy were used to measure the amount of fouling on the surface of the control and main carbon steel samples. The results indicate that the rate of precipitation formation is greatly reduced in the presence of antiscalant.

In this study, the effect of simultaneous doping of magnesium, calcium, and copper ions on the properties of zinc oxide doped with cobalt was investigated. The sol-gel method has been used for the synthesis of nanoparticles. The structural and optical properties of the synthesized nanoparticles were investigated using X-ray diffraction (XRD), infrared spectroscopy (FTIR), and DRS spectroscopy. Rietveld’s analysis of XRD patterns confirmed the hexagonal wurtzite phase structure. In infrared spectroscopy, bands related to this structure were detected at a wavenumber of about 400 cm-1. Microscopic images showed that fine zinc oxide particles with dimensions of 10 to 20 nm were agglomerated by sticking to each other. In addition, it was found that the bandgap of the doped samples was reduced relative to pure zinc oxide. Due to the addition of cobalt as a dopant, the bandgap energy reduced from 3.0 eV to 2.5 eV. Also, copper ion as a second dopant in the composition caused a further reduction in the bandgap and reaches about 2.1 eV. The examination of the samples by the VSM device showed that the magnetic properties of the particles are enhanced by the addition of cobalt dopant and reach 40 memu / g. However, as a result, the magnetic property is reduced with other co-doped samples. copper and cobalt co-doped zinc oxide have no significant changes in magnetic properties. Therefore, with a lower bandgap and the best magnetic properties, this sample can be considered the most suitable sample in the dilute magnetic semiconductors’ application.