High-temperature XRD study of thermally induced structural and chemical changes in iron oxide nanoparticles embedded in porous carbons

Schettino, Miguel A.; Freitas, Jair C. C.; Morigaki, Milton K.; Nunes, E; Cunha, Ana Cristina Barros da; Passamani, E. C.; Emmerich, Francisco G.

doi:10.1007/s11051-010-9905-6

Cited by 9 publications

(4 citation statements)

References 13 publications

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“…7, where the weight losses associated with the formations of wüstite and austenitic iron are indicated. A steep weight loss is observed in the TG curve accompanying this last reduction stage, similar to what has been found for other carbon-based nanocomposites containing nanostructured iron oxides (Schettino et al 2010(Schettino et al , 2012. Upon cooling, c-Fe is converted into a-Fe (ferrite), which is the dominant phase at room temperature in the sample heat treated at 1000°C.…”

Section: Study Of Chemical and Structural Changes Caused By Thermal Tsupporting

confidence: 84%

“…The formation of similar phases has also been previously observed by heat treatments performed under non-oxidizing atmosphere in other iron-carbon nanocomposites (Inagaki et al 1999;Sajitha et al 2004;Schettino et al 2010Schettino et al , 2012. However, the amount and the crystallinity of the phases formed at each temperature are largely dependent on the nature of the carbon support and of the Fe-containing nanoparticles, as well as on the type of atmosphere used in the heat treatments.…”

Section: Study Of Chemical and Structural Changes Caused By Thermal Tsupporting

confidence: 73%

“…In these experiments, synchrotron radiation was used, allowing the recording of good-quality diffractograms in short time at several temperatures during heating and cooling (Schettino et al 2010). The results are displayed in Fig.…”

Section: Study Of Chemical and Structural Changes Caused By Thermal Tmentioning

confidence: 99%

“…Probably the most frequently used routes involve the impregnation of the carbon support in an aqueous suspension containing the iron precursor (e.g., an iron salt) Zhang et al 2007;Hristovski et al 2009;Muñiz et al 2009;Cooper et al 2010). Other reported methods are the direct decomposition of iron pentacarbonyl inside an activated carbon (Schettino et al 2010(Schettino et al , 2012 and the simultaneous pyrolysis of ferrocene and a carbon precursor (Sajitha et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of nanostructured iron oxides dispersed in carbon materials and in situ XRD study of the changes caused by thermal treatment

et al. 2015

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Carbon-based magnetic nanocomposites are of large interest for applications in catalysis, magnetic separation, water cleaning, and magnetic resonance imaging, among others. This work describes the synthesis of nanocomposites consisting of iron oxides dispersed into a char (obtained from the carbonization at 700°C of a lignocellulosic precursor) and the study of the thermal transformations occurring in these materials as a consequence of heat treatments. The materials were prepared by impregnation of the char with iron nitrate in the presence of ammonium hydroxide in aqueous suspension. X-ray diffraction experiments performed using synchrotron radiation and Mössbauer spectroscopy showed that the as-prepared material was composed of amorphous Fe 3? oxides. Scanning electron microscopy images combined with energy-dispersive X-ray spectrometry indicated a homogeneous dispersion of iron oxides and of silica particles (naturally present in the lignocellulosic precursor) throughout the char. X-ray diffractograms recorded in situ during the heat treatment of the as-prepared material showed the presence of small hematite crystallites (average size *22 nm) starting from ca. 300°C. Further heating caused a progressive growth of the hematite crystallites up to ca. 500°C, when the conversion to magnetite (Fe 3 O 4 ) started to take place. At higher temperatures, wüstite (Fe 1-x O) was detected as an intermediate phase and austenitic iron (c-Fe) became the dominant phase at temperatures from 900°C. A steep weight loss was observed in the TG curve accompanying this last reduction stage; upon cooling, c-Fe was converted into a-Fe (ferrite), which was the dominant phase at room temperature in this heat-treated sample.

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Section: Study Of Chemical and Structural Changes Caused By Thermal Tsupporting

confidence: 84%

Section: Study Of Chemical and Structural Changes Caused By Thermal Tsupporting

confidence: 73%

Section: Study Of Chemical and Structural Changes Caused By Thermal Tmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of nanostructured iron oxides dispersed in carbon materials and in situ XRD study of the changes caused by thermal treatment

et al. 2015

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Synthesis and characterization of nanostructured iron compounds prepared from the decomposition of iron pentacarbonyl dispersed into carbon materials with varying porosities

et al. 2016

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Enhancing graphitization and mesoporosity by cobalt in activated carbons obtained from peach stone

Campello-Gómez,

Cruz,

Rambo

et al. 2024

J Nanopart Res

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High-temperature XRD study of thermally induced structural and chemical changes in iron oxide nanoparticles embedded in porous carbons

Cited by 9 publications

References 13 publications

Synthesis of nanostructured iron oxides dispersed in carbon materials and in situ XRD study of the changes caused by thermal treatment

Synthesis of nanostructured iron oxides dispersed in carbon materials and in situ XRD study of the changes caused by thermal treatment

Synthesis and characterization of nanostructured iron compounds prepared from the decomposition of iron pentacarbonyl dispersed into carbon materials with varying porosities

Enhancing graphitization and mesoporosity by cobalt in activated carbons obtained from peach stone

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