Synthesis, structure and exchange bias in Cr2O3/CrO2/Cr2O5 particles

Si, Peng; Wang, H.X.; Jiang, Wen; Lee, J.G.; Choi, Chul-Jin; Liu, J.J.

doi:10.1016/j.tsf.2011.03.097

Cited by 22 publications

(15 citation statements)

References 11 publications

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“…It is reasonable that there are two reactions, which correspond to Cr(III) oxidation and Cr(VI) reduction, respectively. In addition, Cr(IV) is detected at 200°C and 300°C, but disappears over 400°C, possibly indicating the formation of mixed-valence chromium oxide, which would decompose as temperature increases to 400°C (Harrison et al, 1998;Si et al, 2011). Simulated sludge samples heated at various temperatures were analyzed by FT-IR technique and the result is shown in Fig.…”

Section: Temperature Range: 200-400°cmentioning

confidence: 99%

The role of temperature on Cr(VI) formation and reduction during heating of chromium-containing sludge in the presence of CaO

et al. 2015

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Section: Temperature Range: 200-400°cmentioning

confidence: 99%

The role of temperature on Cr(VI) formation and reduction during heating of chromium-containing sludge in the presence of CaO

et al. 2015

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“…Ferromagnetic CrO 2 has attracted intensive research interest for its high spin polarization and potential applications in magnetoelectronic devices [4,5]. However, CrO 2 is metastable and much synthesis work has been directed toward the controlling of preparation conditions [6].…”

Section: Introductionmentioning

confidence: 99%

Structure and magnetic properties of Cr/Cr2O3/CrO2 microspheres prepared by spark erosion and oxidation under high pressure of oxygen

Jin

Xiao

et al. 2013

Materials Letters

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“…While this value may seem to be in contradiction with the chemical shift theory, CrO 2 has been observed to have a lower binding energy than Cr 3+ species repeatedly. 40,45,53 This peak, however, does not appear to be present with appreciable intensity for any of the stains.…”

Section: Resultsmentioning

confidence: 83%

“…The presence of CrO 2 is plausible under these conditions, as it has been repeatedly observed under oxidizing conditions. 26,31,34,45 The Cr 2p 3/2 peak for CrO 2 is anticipated to appear around 575.2 eV. While this value may seem to be in contradiction with the chemical shift theory, CrO 2 has been observed to have a lower binding energy than Cr 3+ species repeatedly.…”

Section: Resultsmentioning

confidence: 93%

“…27,28,48 Thermal decomposition of CrO 3 may begin at temperatures as low as 200 • C, which may cause melting and effervescing, resulting in a loss of oxygen. 26,31,34,45 Based on this literature background, different discolored regions may be understood by proposing a succession of events regarding volatile chromium deposition and its subsequent breakdown. This sequence of events is illustrated below in Figures 8-10.…”

Section: Resultsmentioning

confidence: 99%

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XPS Characterization of Aluminosilicate Fibers Post Interaction with Chromium Oxyhydroxide at 100–230°C

Tatar¹,

Gannon²,

Swain³

et al. 2018

J. Electrochem. Soc.

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Chromium containing materials, e.g. stainless steels, are commonly used in high temperature (>500 • C) applications such as solid oxide fuel cell (SOFC) stacks, combustion exhaust systems, and in various chemical process equipment. At these temperatures and in oxidizing atmospheres, chromium oxide (chromia) surface layers form and grow, effectively protecting the underlying alloy. Also known to form under these conditions, however, are volatile chromium species such as CrO 2 (OH) 2 and CrO 3 . Formation of these volatile species may have detrimental effects not only on the source material, but also on surrounding materials in the system which may interact with these species. To better understand how volatile chromium species interact with materials, volatile chromium species were generated from ferritic stainless steel (FSS) T409 at 700 • C and directed into aluminosilicate fibers at 100-230 • C for 150 hours. Post exposure fibers were noted to possess yellow, brown, and/or green stained regions which were isolated and characterized using X-ray photoelectron spectroscopy (XPS). Examination of Cr 2p 3/2 peaks revealed varied Cr(VI) content and Cr(III) multiplet-split components for different discolored regions. Possible explanations for differences in chromium content by discoloration color are discussed. The volatilization of chromium species from chromium containing materials is a well-documented phenomenon which holds consequences for SOFCs, human health, and the environment. Using chromia as an example for a source, in the presence of oxygen and absence of water vapor, the dominant volatilization pathway proceeds according to Reaction 1.If, however, water vapor is present in addition to oxygen, then the dominant volatilization pathway proceeds according to Reaction 2. 1-7The generation of these gas/vapor species is well understood, but the same cannot be said of how they interact with (e.g. condense onto) other materials. This is of great importance for human health and the environment considering that chromium species may take toxic forms (hexavalent) or non-toxic forms (trivalent). This relative dearth of understanding also holds negative implications for SOFCs, and so many investigative efforts have been undertaken to understand how CrO 2 (OH) 2 interacts with ceramic components in SOFCs. Electrochemical reduction of CrO 2 (OH) 2 has often been observed to occur at the triple phase boundary (TPB), where cathode, electrolyte, and gas phase meet. [8][9][10] This electrochemical reaction is not limited to the TPB, however, and can occur away from the TPB given: the formation of a continuous chromia layer for hole transport, a mixed conducting electrolyte, or a mixed conducting cathode. 8 While there is evidence for preferential electrochemical reduction of CrO 2 (OH) 2 , 11,12 open circuit chemical reactions have also been observed with cathodes containing Mn or Sr. 13 It should be noted that Cr transport to lanthanum strontium manganite (LSM) was observed via solid state diffusion, whereas vapor deposition o...

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Synthesis, structure and exchange bias in Cr2O3/CrO2/Cr2O5 particles

Cited by 22 publications

References 11 publications

The role of temperature on Cr(VI) formation and reduction during heating of chromium-containing sludge in the presence of CaO

The role of temperature on Cr(VI) formation and reduction during heating of chromium-containing sludge in the presence of CaO

Structure and magnetic properties of Cr/Cr2O3/CrO2 microspheres prepared by spark erosion and oxidation under high pressure of oxygen

XPS Characterization of Aluminosilicate Fibers Post Interaction with Chromium Oxyhydroxide at 100–230°C

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