Phase transition behavior in Fe2O3 nanofibers

Han, Chang; Shi, Jing; Wang, Yu; Xie, Kun; Song, Xiaoping; Li, Hongzhong; Cai, Anjiang; Yun, Sining

doi:10.1016/j.apsusc.2019.145179

“…The Raman spectra of the three sets of samples further reveal the successful formation of the In 2 O 3 /Fe 2 O 3 composites. As shown in Figure g, the Raman characteristic peaks at 306, 366, 494, and 629 cm –1 belong to cubic phase In 2 O 3 , while the characteristic peak at 1315 cm –1 belongs to the double magnet scattering of hematite Fe 2 O 3 …”

Section: Resultsmentioning

confidence: 96%

“…As shown in Figure 2g, the Raman characteristic peaks at 306, 366, 494, and 629 cm −1 belong to cubic phase In 2 O 3 , 24 while the characteristic peak at 1315 cm −1 belongs to the double magnet scattering of hematite Fe 2 O 3 . 25 Transmission electron microscopy (TEM) can be used to study the microstructural information of the samples in more presence of a large number of mesopores. 26 The specific surface areas of In 4b−4g.…”

mentioning

confidence: 99%

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In₂O₃/Fe₂O₃ Core–Shell Nanotubes

Zhao,

Cao,

Wang

et al. 2023

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In 2 O 3 is an optimal material for sensitive detection of carbon monoxide (CO) gas due to its low resistivity and high catalytic activity. Yet, the gas response dynamics between the CO gas molecules and the surface of In 2 O 3 is limited by its solid structure, resulting in a weak gas response value and sluggish electron transport. Herein, we report a strategy to synthesize porous In 2 O 3 /Fe 2 O 3 core−shell nanotubes derived from In/Fe bimetallic organic frameworks. The fabricated porous In 2 O 3 /Fe 2 O 3 -4 core−shell nanotubes present outstanding gas sensitivities, including a response value 3.8 times (33.7 to 200 ppm CO at 260 °C) higher than that of monometallic-derived In 2 O 3 (8.7), ultrashort response and recovery times (23/76 s) to 200 ppm CO, low detection limit (1 ppm), promising selectivity, and long-term stability. The enhanced sensing mechanisms are clarified by the combination of experiment and firstprinciples calculations, showing that the synergetic strategy of higher adsorption energy, increased electrical conductivity, higher electron transfer numbers, and larger specific surface area of porous core−shell structures promotes the surface activity and charge transfer efficiency. The present work paves a way to tune gas-sensing materials with special morphologies for the development of highperformance CO sensors. KEYWORDS: bimetallic organic frameworks, In 2 O 3 /Fe 2 O 3 core−shell nanotubes, porous structure, CO, gas sensing

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“…78 For example, Han et al revealed novel phase transition properties of electrospun Fe(NO 3 ) 3 /PVP NFs during annealing. 79 Upon the cooling process, a gradual transformation from the α-diamond central hexagonal structure to the β-centripetal cubic structure was observed using in situ TEM. Combining the temperature dependence of the magnetization curves measured ranging from 15 to 390 K and the hysteresis loops measured between 30 and 300 K, the Morin transition temperature was determined to be 300 K and the phase transition process occurred between 245 and 257 K. This abnormal transformation was related to Fe 2 O 3 NFs with the shape of a "necklace", which caused internal strain due to the arrangement of thin and thick parts, and electron diffraction patterns confirmed the presence of internal strain.…”

Section: Electrospun Polymer-based Nfs As Nanoreactorsmentioning

confidence: 99%

Electrospun advanced nanomaterials for in situ transmission electron microscopy: Progress and perspectives

Zhao,

Li,

Lv

et al. 2023

InfoMat

3

0

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Electrospun nanofibers (NFs) have shown excellent properties including high porosity, abundant active sites, controllable diameter, uniform and designable structure, high mechanical strength, and superior resistance to external destruction, which are ideal nanoreactors for in situ characterizations. Among various techniques, in situ transmission electron microscopy (TEM) has enabled operando observation at the atomic level due to its high temporal and spatial resolution combined with excellent sensitivity, which is of great importance for rational materials design and performance improvement. In this review, the basic knowledge of in situ TEM techniques and the advantages of electrospun nanoreactors for in situ TEM characterization are first introduced. The recent development in electrospun nanoreactors for studying the physical properties, structural evolution, phase transition, and formation mechanisms of materials using in situ TEM is then summarized. The electrochemical behaviors of carbon nanofibers (CNFs), metal/metal oxide NFs, and solid‐electrolyte interphase for different rechargeable batteries are highlighted. Finally, challenges faced by electrospun nanoreactors for in situ TEM characterization are discussed and potential solutions are proposed to advance this field.image

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“…The CI particles may easily be exposed to air during handling and storage, thus giving rise to any Fe O phase on the surface of the sample 5 . Among iron oxide materials, hematite ( -Fe O ), an n -type semiconductor, is known as the most stable iron oxide under ambient condition 11 . It has many application fields such as catalysts, gas sensors, solar cells, and so on due to its environmentally friendly characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…Unlike in CI exhibiting typical ferromagnetic hysteresis loops 5 , 7 , 12 , 13 , hematite undergoes an anomalous magnetic transition, so-called Morin (spin reorientation) transition due to its antiferromagnetic properties 11 , 14 – 19 . It is a well known antiferromagnetic insulator with antiparallel sublattice that above the Morin temperature ( = 260 K) a small sublattice canting takes place due to its internal antisymmetric superexchange, Dzyaloshinskii–Moriya (DM), interaction.…”

Section: Introductionmentioning

confidence: 99%

Enhanced anomalous magnetization in carbonyl iron by Ni+ ion beam irradiation

Park

¹

,

Jang

²

,

Cho

³

et al. 2021

Sci Rep

1

0

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We investigate the magnetic properties in carbonyl iron (CI) particles before and after Ni$$^{+}$$ + and H$$^{+}$$ + ion beam irradiation. Upon increasing temperatures, the saturation magnetization ($$M_{\text {s}}$$ M s ) in hysteresis loops exhibits an anomalous increase at a high temperature for the unirradiated and the Ni$$^{+}$$ + -beam-irradiated samples, unlike in H$$^{+}$$ + -beam-irradiated sample. Moreover, the magnetization values at low and high temperatures are more intense after Ni$$^{+}$$ + beam irradiation, whereas after H$$^{+}$$ + beam irradiation those are remarkably suppressed. Hematite ($$\alpha $$ α -Fe$$_{2}$$ 2 O$$_{3}$$ 3 ) phase introduced on the surface of our CI particles undergoes the Morin transition that was observed in our magnetization-temperature curves. The Morin transition causing canted antiferromagnetism above the Morin temperature was found in the unirradiated and Ni$$^{+}$$ + -beam-irradiated samples, but not in H$$^{+}$$ + -beam-irradiated sample. It is thus revealed that the CI particles undergoing the Morin transition cause the anomalous increase in $$M_{\text {s}}$$ M s . We may suggest that Ni$$^{+}$$ + ion beam increases uncompensated surface spins on the CI particles resulting in a more steep Morin transition and the intensified $$M_{\text {s}}$$ M s . Ion-beam irradiation may thus be a good tool for controlling the magnetic properties of CI particles, tailoring our work for future applications.

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Phase transition behavior in Fe2O3 nanofibers

Cited by 11 publications

References 92 publications

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In₂O₃/Fe₂O₃ Core–Shell Nanotubes

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In₂O₃/Fe₂O₃ Core–Shell Nanotubes

Electrospun advanced nanomaterials for in situ transmission electron microscopy: Progress and perspectives

Enhanced anomalous magnetization in carbonyl iron by Ni+ ion beam irradiation

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Phase transition behavior in Fe2O3 nanofibers

Cited by 11 publications

References 92 publications

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In2O3/Fe2O3 Core–Shell Nanotubes

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In2O3/Fe2O3 Core–Shell Nanotubes

Electrospun advanced nanomaterials for in situ transmission electron microscopy: Progress and perspectives

Enhanced anomalous magnetization in carbonyl iron by Ni+ ion beam irradiation

Contact Info

Product

Resources

About

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In₂O₃/Fe₂O₃ Core–Shell Nanotubes

Fast and Sensitive Detection of CO by Bi-MOF-Derived Porous In₂O₃/Fe₂O₃ Core–Shell Nanotubes