Synthesis by the solution combustion process and magnetic properties of iron oxide (Fe 3 O 4 and α-Fe 2 O 3 ) particles (original) (raw)
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This article describes the solution combustion synthesis technique as applicable to iron oxide powder production using urea as fuel and ferric nitrate as an oxidizer. It focuses on the thermodynamic modeling of the combustion reaction under different fuel-to-oxidant ratios. X-ray diffraction showed magnetite (Fe 3 O 4 ) and hematite (a-Fe 2 O 3 ) phase formations for the as-synthesized powders. The smallest crystallite size was obtained by stoichiometric chemical reaction. The magnetic properties of the samples are also carefully discussed as superparamagnetic behavior.
Journal of Materials Science, 2007
This article describes the solution combustion synthesis technique as applicable to iron oxide powder production using urea as fuel and ferric nitrate as an oxidizer. It focuses on the thermodynamic modeling of the combustion reaction under different fuel-to-oxidant ratios. X-ray diffraction showed magnetite (Fe 3 O 4 ) and hematite (a-Fe 2 O 3 ) phase formations for the as-synthesized powders. The smallest crystallite size was obtained by stoichiometric chemical reaction. The magnetic properties of the samples are also carefully discussed as superparamagnetic behavior.
Solution Combustion Synthesis and Characterization of Magnetite, Fe 3 O 4 , Nanopowders
Journal of the American Ceramic Society, 2012
Combustion synthesis of Fe 3 O 4 and properties of the resulted powders have been discussed in relation to reaction atmosphere (in air/in the absence of air) and used fuel (sucrose, citric acid and glucose). Conducting the combustion reactions in air caused the rapid oxidation of Fe 2+ to Fe 3+ under the influence of the atmospheric oxygen; therefore the final reaction product was a mixture of a-Fe 2 O 3 and c-Fe 2 O 3 . In order to avoid the oxidation of Fe 2+ to Fe 3+ a simple but efficient solution has been suggested: combustion reactions were carried out in a round bottom flask and the evolving gases were bubbled in a beaker filled with water. This solution allowed the preparation of Fe 3 O 4 nanopowders, with crystallite size varying from 10 nm (glucose) to 18 nm (citric acid). Depending on the used fuel, the specific surface area of the magnetite powders varied between 56 m 2 /g (citric acid) and 106 m 2 /g (glucose). The saturation magnetization of Fe 3 O 4 powders prepared in the absence of air ranged between 55.3 emu/g (glucose) and 59.4 emu/g (sucrose).
Chemistry of Materials, 2004
Solution combustion synthesis of different oxides involves a self-sustained reaction between an oxidizer (e.g., metal nitrate) and a fuel (e.g., glycine, hydrazine). The mechanism of synthesis for three major iron oxide phases, i.e., R-and γ-Fe 2 O 3 and Fe 3 O 4 , using the combustion approach and a combination of simple precursors such as iron nitrate and oxalate, as well as different fuels, is investigated. Based on the obtained fundamental knowledge, for the first time in the literature, the above powders with well-crystalline structures and surface areas in the range 50-175 m 2 /g are produced using a single approach while simultaneously avoiding additional calcination procedures. It is also shown that utilizing complex fuels and complex oxidizers is an attractive methodology to control the product composition and properties.
1997
Highly dispersed -Fe 2 O 3 powders with particle sizes down to 5 nm were directly synthesized by combustion of solutions of iron pentacarbonyl or iron(III) acetylacetonate in toluene in an oxyhydrogen flame. The particle size as well as other properties of the obtained powders can be controlled simply by varying the iron concentration in the starting solutions. Phase composition, morphological and magnetic properties of the powders were studied. The reasons for the formation of -Fe 2 O 3 are discussed by means of structure-chemical/kinetic considerations. The materials are interesting as recording materials, or ferrofluids, or for colour imaging and bioprocessing.
Direct synthesis of maghemite, magnetite and wustite nanoparticles by flame spray pyrolysis
Advanced Powder Technology, 2009
Magnetic iron-oxide nanoparticles have been prepared by flame spray pyrolysis (FSP) under controlled atmosphere. This way controlled and direct flame synthesis of Fe 2 O 3 (maghemite), Fe 3 O 4 (magnetite) and FeO (wustite) particles is possible by a scalable process. The Fe oxidation state was controlled by varying the fuel to air ratio during combustion as well as by varying the valence state of the applied Fe precursor. The as-prepared materials were characterized by electron microscopy, nitrogen adsorption, X-ray diffraction and Raman spectroscopy. Magnetic properties were investigated with SQUID, which unravelled superparamagnetic behaviour for all materials and typical features for the corresponding crystal structures and particle sizes. Maximum magnetisation was achieved for a mixture of maghemite and magnetite.
Moderate thermal oxidation of iron oxide found in nature as raw materials for ferrite magnets
Journal of Physics: Conference Series, 2018
Iron oxide found in nature with high iron oxide content has potential to be utilized as raw material for magnetic application. In this study, an attempt has been made to increase hematite content through thermal oxidation or roasting in moderate temperature with additional oxygen gas to accommodate oxidation. Iron oxide powders were milled in 6 hours then washed and dried. Roasting processwere performed at four varying temperatures of 480°C, 520°C, 560°C, and 600°C with oxygen influx 3L min-1, preceded by isothermal holding at 385°C. TGA-DSC (thermogravimetric analysis-differential scanning calorimetry) and XRD (X-Ray Diffraction) characterization has been performed to understand iron oxide behavior in response to thermal oxidation at moderate temperature. It is observed that two main reactions are clearly distinguished. In DTG curve, first peak indicate reduction followed by oxidation at the second peak. XRD results has shown that the highest content of α Fe 2 O 3 was achieved by roasting at 600 °C for 1 hour which produced hematite portion of 31 wt. %, yet it is still insufficient to be utilized as raw material for ferrite based magnets fabrication. To prevent reduction reaction of Fe 3 O 4 which will retard the oxidation process, it is suggested to avoid isothermal run or lower heating rate at temperature below 406°C
Surfactant-Assisted Combustion Method for the Synthesis of α-Fe 2 O 3 Nanocrystalline Powders
In this present work, a new surfactant-assisted combustion method has been performed to synthesize α-Fe2O3 powders by using iron nitrate as an oxidizer, glycine as a fuel and TWEEN 80 as a non-ionic surfactant. The effects of the fuel at different molar ratios assisted with surfactant are investigated with XRD, DT/TGA, UV-Vis Spectroscopy, FT-IR and SEM techniques. The investigation range of molar ratios of oxidizer is 0.1M; fuels are of molar ratios 0.1M, 0.15M, 0.2M, 0.25M and 0.3M and with surfactant ratio 0.07M have been studied. Structural characterization of different samples is investigated by X-ray Diffractometer. From X-ray Diffraction data lattice parameters, crystallite sizes, micro strains, cell volumes and porosities of the samples are calculated. The average crystallite sizes of the samples are obtained by Debye-Schererr's formula and Williamson-Hall plot. The XRD result also indicates rhombohedral system (R3c) with lattice parameters a=5.035Ao and c= 13.748Ao with the JCPDS data card no: 33-0664. Thermal studies of the samples are analyzed by TG/DTA analysis. Particle size distributions were observed by Particle size analyzer. Surface morphology of the samples is studied by scanning electron microscopy.
Redox synthesis of magnetite powder under mixing-grinding of metallic iron and hydrated iron oxide
Solid State Ionics, 2004
Redox synthesis of magnetite powder from metallic iron and FeO(OH) under mixing-grinding with the assistance of H2O2 as an oxidizing reagent has been proposed. Deformability of the metal–oxide system induces the kneading of am-FeO(OH) into metallic iron to activate, while the iron is oxidized to Fe(OH)2 and/or FeO by H2O2 contained in the grinding liquid (acetone). Only the reaction product, γ-Fe3O4, is obtained. The adhesivity of the powder system due to iron reduces with the progress in synthesis reaction forming non-deformable magnetite powder to result in its dispersion into acetone. The primary particle size of the γ-Fe3O4 powders formed is less than 100 nm. The saturation magnetization of the synthesized γ-Fe3O4 is 9.24×10−5 Wb m g−1, which is about 90% of the commercially available fine γ-Fe3O4 powders with needle-like shapes.