Synthesis, Characterization, and Magnetic Properties of Fe3O4Thin Films Prepared via a Sol–Gel Method

Chang, Hong Suk; Chiou, Chuei-Chang; Chen, Yiwei; Sheen, S.R.

doi:10.1006/jssc.1996.7159

Cited by 24 publications

(12 citation statements)

References 11 publications

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“…Simply put, the evaporation of the ethanol from the xerogel sample exerted substantial capillary forces on the gel's pore structure, which resulted in shrinkage of the pores, relative to the aerogel sample. The surface areas reported in Table for the Fe 2 O 3 gels (300−400 m 2 /g) are significantly higher than those reported for other sol−gel preparations of Fe 2 O 3 solids (10−80 m 2 /g). , These results, along with the low-density measurements, indicate that the dry Fe 2 O 3 gels made by this method are unique and new materials that should be evaluated in applications utilizing Fe 2 O 3 . − …”

Section: Resultsmentioning

confidence: 73%

“…The fields of chemistry, medicine, soil science, geology, and corrosion science have previous and ongoing interests in the iron oxides . Iron oxides have found use in industry as inorganic pigments, ceramics, and magnetic storage media. − Academic pursuits have utilized iron(III) oxides and iron(III) oxo-bridged monomers and oligomers as catalysts, − electrochemical sensors, − and model compounds for biologically important protein systems. , In all of these areas there is a need for straightforward and dependable synthetic approaches to the iron(III) oxides…”

Section: Introductionmentioning

confidence: 99%

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Use of Epoxides in the Sol−Gel Synthesis of Porous Iron(III) Oxide Monoliths from Fe(III) Salts

et al. 2001

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Iron oxide-based porous solids were prepared by a sol−gel process using Fe(III) salts in various solvents. It was observed that the addition of propylene oxide to Fe(III) solutions resulted in the formation of transparent red-brown monolithic gels. The resulting gels were converted to either xerogels by atmospheric drying or aerogels by supercritical extraction with CO2(l). Some of the dried materials were characterized by nitrogen adsorption and desorption analysis and transmission electron microscopy (TEM). The results of those analyses indicate that the materials have high surface areas (∼300−400 m2/g), pore sizes with mesoporic dimensions (2−23 nm), and a microstructure made up of 5−10 nm diameter clusters of iron(III) oxide. The dependence of both gel formation and its rate was studied by varying the epoxide/Fe(III) ratio, the Fe(III) precursor salt, amount of water (H2O/Fe(III)) present, and the solvent employed. All of these variables were shown to affect the rate of gel formation and provide a convenient control of this parameter. Finally, an investigation of the mechanism of Fe2O3 gel formation was performed. Both pH and nuclear magnetic resonance (NMR) studies suggest that the added epoxide acts as an irreversible proton scavenger that induces the Fe(III) species to undergo hydrolysis and condensation to form an inorganic iron oxide framework. This method can be extended to prepare other transition- and main-group metal oxide materials.

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Section: Resultsmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Use of Epoxides in the Sol−Gel Synthesis of Porous Iron(III) Oxide Monoliths from Fe(III) Salts

et al. 2001

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“…After the sample was passivated, an extra phase Fe 3 O 4 (magnetite) along with the dominant FeCO 3 , was identified by GIXRD (Figure ). The composition of the film was quantified using the Rietveld refinement technique .…”

Section: Resultsmentioning

confidence: 99%

Chemistry and Structure of the Passive Film on Mild Steel in CO₂ Corrosion Environments

Han

Young

Colijn

et al. 2009

Ind. Eng. Chem. Res.

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The passivation process was carried out and monitored employing a three electrode electrochemical glass cell. Surface analysis using grazing incidence X-ray diffraction (GIXRD) elucidated that trace magnetite in the dominant siderite (FeCO 3 ) was responsible for the passivation. Transmission electron microscopy (TEM) with the energy dispersive X-ray fluorescence (EDX) technique was used to determine the structure of the passive layer and confirm its chemistry. A passive phase tens of nanometers thick was observed beneath iron carbonate scale and at the crystal boundaries. Scanning transmission electron microscopy (STEM)/EDX profiles suggest that this phase is not a carbonate containing compound since only oxygen and iron were observed. This indicates that the possible chemical compound for the passive phase is an iron oxide, agreeing with the previous GIXRD surface analysis. Fe 3 O 4 as a passive film was confirmed.

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“…The spectrum could be analyzed with two magnetic sextets with low IS values (0.44 and 0.41 mm/s), which indicate the existence of only trivalent iron. Calcination, therefore, induced the oxidation of Fe 2+ to Fe 3+ and the subsequent transformation of magnetite to γ-Fe 2 O 3 according to the well-known oxidation reaction of magnetite to maghemite under oxidative conditions: …”

Section: Resultsmentioning

confidence: 99%

Magnetically Modified Al₂O₃ Pillared Clays

1999

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Surface modification of alumina pillared montmorillonite with magnetic iron oxide nanoparticles has been achieved by using as precursor a colloidal solution of magnetite in poly(vinyl alchohol). Two synthetic routes were developed differing in the number of steps. The magnetic and adsorption properties of the modified products were studied using Mo ¨ssbauer spectroscopy, magnetization, and surface area measurements. All measurements showed that their magnetic and adsorption properties depend on the way of preparation. The Mo ¨ssbauer spectra exhibited different superparamagnetic behavior for each modified product, whereas sorption analysis gave different surface areas and structural characteristics. TEM reveals the nano size of the iron oxides and furthermore their random dispersion at the external surfaces of the clay.

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Synthesis, Characterization, and Magnetic Properties of Fe3O4Thin Films Prepared via a Sol–Gel Method

Cited by 24 publications

References 11 publications

Use of Epoxides in the Sol−Gel Synthesis of Porous Iron(III) Oxide Monoliths from Fe(III) Salts

Use of Epoxides in the Sol−Gel Synthesis of Porous Iron(III) Oxide Monoliths from Fe(III) Salts

Chemistry and Structure of the Passive Film on Mild Steel in CO₂ Corrosion Environments

Magnetically Modified Al₂O₃ Pillared Clays

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Synthesis, Characterization, and Magnetic Properties of Fe3O4Thin Films Prepared via a Sol–Gel Method

Cited by 24 publications

References 11 publications

Use of Epoxides in the Sol−Gel Synthesis of Porous Iron(III) Oxide Monoliths from Fe(III) Salts

Use of Epoxides in the Sol−Gel Synthesis of Porous Iron(III) Oxide Monoliths from Fe(III) Salts

Chemistry and Structure of the Passive Film on Mild Steel in CO2 Corrosion Environments

Magnetically Modified Al2O3 Pillared Clays

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Product

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Chemistry and Structure of the Passive Film on Mild Steel in CO₂ Corrosion Environments

Magnetically Modified Al₂O₃ Pillared Clays