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

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.

Aventurine glaze is one of the Macrocrystalline glaze that is the result of saturation of iron oxide in the glaze. In general, the formation of crystals in crystalline glazes requires special conditions, so the purpose of this study is to investigate the effective factors on the formation of aventurine glaze of iron oxide including combination, temperature, firing conditions and surface that is used. And also effective factors that improve crystals were investigated. The question is asked: what is the effect of each factor on the formation and improvement of the features of the aventurine glaze. The current research is functional research and experimental in terms of method, and has been done in a laboratory-studio. In this section, raw materials which include silica, kaolin, borax and iron oxide in appropriate amounts were combined by a ball mill and fired in an electric kiln and then analyzed. The method of analysis has been used in both quantitative and qualitative analysis. Quantitative analysis was used to examine the quantities of basic material and qualitative analysis was used to examine the visual features that were created in the glaze. The method of data collection in this research is the library method in the theoretical section and observation in the glaze production section. The results have shown that red clay bodies are not suitable for aventurine glaze, while white bodies that fired in low temperature are suitable. The type and amount of iron oxide used is effective in creating and improving crystals in this glaze. The best effects of aventurine were achieved with two types of iron oxides that include black iron oxide and ferric oxide. And 20% and above amount of iron oxide were the best amounts for Aventurine glaze, we can see the most desirable quality of crystals in terms of size and brightness, in terms of temperature, the most desirable glazes in terms of quantity of crystals and brightness, at 1080 degrees Centigrade. The amount of glaze base materials, which include silica, kaolin, boron oxide and sodium oxide, affects the quality of the aventurine glaze, and the lower the kaolin base, the better crystals have grown.

In this work, a multilayer magnetic biosensor (SiO2/CoFeSiB/Al2O3/Cr/Au) based on the giant magnetoimpedance (GMI) effect, is designed and fabricated by micro-electromechanical system (MEMS) technology. Co68.15Fe4.3Si12.5B15‎ alloy ingot was prepared using vacuum arc remelting (VAR) furnace and then amorphous ribbon was produced using melt-spinning process. In order to develop the GMI biosensor, a micro-pattern was implicated on the ribbon on a SiO2 substrate using lithography technique with a meander structure containing 10 arms. Al2O3/Cr/Au layers were deposited on the patterned ribbon using RF-sputtering technique. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to evaluate the thermal property and structure of the ribbon. The results showed that the structure of the ribbon is amorphous. Finally, magnetoimpedance evaluation of the sensor was done at frequency range of 1-12 MHz and magnetic field of 0-170 Oe. In the GMI experiment, Fe3O4 nanoparticles were used as sensing elements. Based on the results obtained, it was shown that the maximum GMI ratio was 67% for blank sensor and is reduced by about 13% for sensor with 0.1 mg Fe3O4 at frequency of 9 MHz. Therefore, due to the significant sensitivity of fabricated sensor to iron-oxide nanoparticles, this sensor has potential to be used for bio-magnetic applications.

In this study, yellow ceramic nano pigments based on ZrO2 (zirconium oxide) were synthesized by solid state method using different value of Fe2O3 as dopant. The pigments were dispersed in solvent by a planetary ball mill and then the inks were printed on the ceramic surface using screen printing method. The samples were analyzed using scanning electron microscopy (SEM), X-ray diffraction spectrum (XRD) and CIE Lab Colorimetric Analysis. Results showed that by changing the amount of Fe2O3 dopant from 0.07 to 0.2 gr, the average particle size changed from 170 to134 nm. The colorimetric results revealed that after increasing Fe2O3 dopant, the amount of a* parameter increased from 1.21 to 6.72, b* from 34.72 to 47.53, while L* parameter (lightness) reduced. After printing of pigments on the ceramic surface, the average particle size of each sample decreased; also, the L* (lightness) and a* (red) increased while b* (yellow) decreased.

In this study, Co3O4-15 wt. % Fe2O3 composite powder was synthesized by two methods including: A-simultaneous milling of oxide mixtures (0, 1 and 16 h) and B-separately milling of cobalt oxide (0, 1 and 16 h) and iron oxide (0, 0.5 and 7 h) and then mixing. Average particle size, particle morphology, iron oxide distribution, phase analysis, and heat storage capacity were studied by FE-SEM, XRD and thermogravimetry methods. It was found that preparation method has a significant effect on the above-mentioned parameters. The results showed that decreasing of iron oxide particle size and addition of it to cobalt oxide, increase the heat storage capacity of the material relative to as-received cobalt oxide. It was revealed that samples prepared by method A generally had lower heat storage capacity than samples prepared by method B. In addition, it was found that small-scale particle size of the composite may not necessarily improve heat storage capacity of the material, and spinel phase formation (Fe2O3.CoO) also is a key factor that has a great effect on decreasing the heat storage capacity.

In this paper Fe2O3/BaFe12O19 nanorods were synthesized by a simple low-cost hydrothermal process with large scale production capability. Morphologic characteristics of nanorods such as length, diameter and aspect ratio were controllable. EDTA was used in the synthesis process as the growth control agent. In this investigation the effects of different parameters such as temperature (115, 150 and 180 °C), time (5, 10, 40 h), growth controlling agent (EDTA, PEG400, PEG6000, CA) and basic agent (NaOH and NH3) were also studied. In different conditions different morphologies like spheres with a diameter of 50-100 nm and nanorods with diameters of 50-400 nm and lengths of 1-10 μm were synthesized. Morphological characteristics of the samples were studied by scanning electron microscope (SEM) and magnetic properties were measured by alternative gradient force magnetometer (AGFM). The nanorods of this research could be used for heavy metal ions removal from waste water, catalysts, solar cells and microwave absorbing materials.

In this study, cobalt ferrite (CoFe2O4) nanoparticles were prepared by single-step chemical precipitation method at room temperature for an hour. Cobalt ferrite nanoparticles were synthesized by cobalt sulfate, ferric chloride (III) and ammonium as deposition agent. Structure, particle size distribution and surface morphology of the nanoparticles were studied by X ray diffraction (XRD), transmission electron microscopy (TEM). Also, the magnetic properties of the samples were measured with a vibrating sample magnetometer (VSM). XRD spectrum clearly confirmed the formation of cobalt ferrite particles and lack of the presence of any other phase. The TEM images showed the uniform distribution of particle size. The average particle size was around 20 nm. The VSM results of cobalt ferrite nanoparticles approved the ferrimagnetism of the powders. VSM results of nanoparticles, cobalt ferrite property represents the ferrimagnetism particles.

The backed bricks applied in Chogha Zanbil historical building are simple, glazed and beard with inscription types, and all are from Elamite era (13th century BC). This Elamit complex has been located in the Khuzestan province of Iran. The body colors of the bricks include yellow, brown, red and green-blue and they have the dimensions 10 cm× 35 cm× 35 cm and 8 cm× 37.5 cm× 37.5 cm. Despite, the bricks suffered environmental deteriorations over thousands of years, some of them have relative high hardness and they are still strength. The firing temperature and the baking condition of the bricks is one of the questions posed in Archaeometry. On the other hand, making the new bricks for the restoration purposes of the building requires the technical information about historical ones. Hence, after sampling the various historical bricks, chemical and mineralogical studies carried out by using XRD, FT-IR and chemical analysis (wet chemistry).The studies have shown that adequate amounts of Calcite and Dolomite with fine amorphous silica caused pyroxene phases such as Diopside at a low temperature around 700 oC in some bricks, which has made them more strength. The various color and quality of the bricks is due to lack of temperature control and atmospheric conditions in the preliminary kiln with wood fuel. The use of straw fibers in raw materials prevented cracking over drying and backing. The plant fibers also helped to back the core parts of bricks however incomplete combustion of carbon compounds and imprisonment of soot in the body, causing the defect "Black core" in them.

In this research، magnetite iron oxide nanoparticles were synthesized via coprecipitation method and their colloidal stability was investigated using 3 different comb polymeric surfactants based on polyacrylic acid-co-polyethylene glycol acrylate in water media. The difference of these surfactants is in tree type of polyethylene glycol with molecular weights of 1000، 2000 and 4000 which is connected to hydrophobic acrylate chain. The effects of synthesis temperature and time on particle sizes were studied. The temperature and time range was determined 27-90C and 10-40 min، respectively. To synthesis of magnetite nanoparticles، ferric and ferrous chlorides were precipitated with pH adjustment using ammonia (25 wt %) solution. The size distribution and stability of particles were studied via dynamic light scattering (DLS) and turbidimetry، respectively. The attachment of surfactants on nanoparticles was studied using fourier transform infrared spectroscopy (FTIR). Results showed that the particle sizes are different related to molecular weights of polyethylene glycol in comb polymeric surfactants. The com polymeric surfactant with polyethylene glycol Mw=2000 was lead to lower mean particle size and better stability relative to others. Moreover it was revealed that the best magnitude colloidal stability was with 22 wt % from comb polymeric surfactant having polyethylene glycol Mw=2000 at 70C for 20 min. The hydrodynamic size of particles was 80nm in this condition.

In this study, the magnetite (Fe3O4) nanoparticles were synthesized via chemical coprecipitation method. The effects of synthesis on the size and magnetic properties of them were investigated. The precipitation occurred by pH adjustment of ferrous/ferric mixed salt-solution with ammonium hydroxide addition. The synthesis was performed in the temperature range of 25°C to 80°C in ambient atmosphere. The magnetite nanoparticles were characterized by X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM) analysis. The crystallite size was calculated via reclaimed Sherrer formula. The results show that the magnetite is the major phase for all temperatures and both of the synthesis atmospheres. It was revealed that the temperature is effective for magnetic properties enhancement. A similar result was obtained for magnetite phase formation. The saturation magnetization was obtained 31emu/g to 66 emu/g. It was found that the superparamagnetic property of nanoparticles is reduced by synthesis temperature.