Kinetics and intermediate phases in epitaxial growth of Fe3O4 films from deposition and thermal reduction

Zhang, Xiaozhe; Yang, Sen; Yang, Zhimao; Xu, Xiaoshan

doi:10.1063/1.4961607

Cited by 24 publications

(19 citation statements)

References 46 publications

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“…The formation of hematite is related to the atmospheres used in the heat treatment in this research. Hong et al [44] and Zhang et al [66] described that iron-based materials oxidized at temperatures between 377 • C and 527 • C under steam, and mainly with CO 2 atmospheres, producing negative free energy for the formation of hematite; therefore, under these conditions, part of the magnetite exposed to higher concentrations of oxygen (outermost layers) is oxidized to hematite (Fe 3 O 4 → α-Fe 2 O 3 ) [56,62,66]. Genuzio et al [62] also mentioned that the kinetics of this transformation are very fast and that it depends on the chemical composition and the availability of defects in the crystalline network, which allow for the growth of the new phase through specific crystallographic plans.…”

Section: Discussionmentioning

confidence: 99%

Characterization Study of an Oxide Film Layer Produced under CO2/Steam Atmospheres on Two Different Maraging Steel Grades

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Rovira

et al. 2021

Metals

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Currently, surface treatments lead to inducing a superficial layer of several nanometers up to micrometer, which in some cases can be protective. In this experimental work, an oxide layer was generated under different atmospheres (CO2 and steam atmospheres) during the thermal aging treatment of two different maraging grades, 300 and 350. Afterwards, this layer was microstructural and mechanically characterized by advanced characterization techniques at the micro- and submicron length scale to highlight some information related to the generated oxide layer. The results showed that the oxide layer (in both grades) was made up of several compounds like: TiO2, MoO3, hematite (α-Fe2O3), and CoFe2O4, this being the majority compound distributed homogeneously throughout the layer. Furthermore, a nickel-rich austenitic phase at the interphase was mainly made up cobalt ions (Co2+), instead of iron ions (Fe2+), within the spinel lattice.

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Section: Discussionmentioning

confidence: 99%

Characterization Study of an Oxide Film Layer Produced under CO2/Steam Atmospheres on Two Different Maraging Steel Grades

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Rovira

et al. 2021

Metals

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“…The in-plane epitaxial relation can be extracted from the RHEED pattern, as depicted in Fig. 2b, with a 30° rotation between the in-plane reciprocal unit cell of CFO relative to that of sapphire substrate, which is the same as that of the Fe3O4/Al2O3 films [19]. Time-resolved RHEED was carried out to elucidate the depth profile of the film by in-situ monitoring the top layer of the film during the growth [19].…”

Section: Structural Characterization and Evidence Of Interfacial Reco...mentioning

confidence: 99%

“…2b, with a 30° rotation between the in-plane reciprocal unit cell of CFO relative to that of sapphire substrate, which is the same as that of the Fe3O4/Al2O3 films [19]. Time-resolved RHEED was carried out to elucidate the depth profile of the film by in-situ monitoring the top layer of the film during the growth [19]. RHEED images along the [11 ̅ 00] direction of CFO was taken every 30 seconds during the film growth at a repetition rate of 1 Hz.…”

Section: Structural Characterization and Evidence Of Interfacial Reco...mentioning

confidence: 99%

Colossal intrinsic exchange bias from interfacial reconstruction in epitaxial CoFe2O4/Al2O3 thin films

et al. 2021

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In this work, we demonstrate a massive intrinsic exchange bias (3 kOe) in epitaxial CoFe2O4(111) thin films deposited on Al2O3(0001) substrates. This exchange bias is indicative of intrinsic exchange or a ferromagnetic material combined with an antiferromagnet. The analysis of structure, magnetism and electronic states corroborate that there is an interfacial layer CoO between the CoFe2O4(111) thin film and the Al2O3(0001) substrate. The power-law thickness dependence of the intrinsic exchange bias verifies its interfacial origin. This work suggests interfacial engineering can be an effective route for achieving large exchange bias.

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“…Furthermore, hematite phase is formed due to the atmospheres used during aging process. Zhang et al [41] and Hong et al [42] described that during oxidation between 375 and 526 • C in atmospheres containing water vapor, the outermost layers are exposed to a higher concentration of oxygen, and part of the magnetite oxidizes to hematite (Fe 3 O 4 → α-Fe 2 O 3 ) [40][41][42][43].…”

Section: Eds Quantitative Analysis From Pointsmentioning

confidence: 99%

Oxidation Behavior of Maraging 300 Alloy Exposed to Nitrogen/Water Vapor Atmosphere at 500 °C

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Cardoso

et al. 2021

Metals

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Aging heat treatments in maraging steels are fundamental to achieve the excellent mechanical properties required in several industries, i.e., nuclear, automotive, etc. In this research, samples of maraging 300 alloy were aged using a novel procedure that combines different steps with two atmospheres (nitrogen and water vapor) for several hours. The oxidized surface layer was chemical, microstructural and micromechanically characterized. Due to the thermodynamic and kinetic conditions, these gases reacted and change the surface chemistry of this steel producing a thin iron-based oxide layer of a homogeneous thickness of around 500 nm. Within the aforementioned information, porosity and other microstructural defects showed a non-homogeneous oxide, mainly constituted by magnetite, nickel ferrite, cobalt ferrite, and a small amount of hematite in the more external parts of the oxide layer. In this sense, from a chemical point of view, the heat treatment under specific atmosphere allows to induce a thin magnetic layer in a mixture of iron, nickel, and cobalt spinel ferrites. On the other hand, the oxide layer presents an adhesive force 99 mN value that shows the capability for being used for tribological applications under sliding contact tests.

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Kinetics and intermediate phases in epitaxial growth of Fe3O4 films from deposition and thermal reduction

Cited by 24 publications

References 46 publications

Characterization Study of an Oxide Film Layer Produced under CO2/Steam Atmospheres on Two Different Maraging Steel Grades

Characterization Study of an Oxide Film Layer Produced under CO2/Steam Atmospheres on Two Different Maraging Steel Grades

Colossal intrinsic exchange bias from interfacial reconstruction in epitaxial CoFe2O4/Al2O3 thin films

Oxidation Behavior of Maraging 300 Alloy Exposed to Nitrogen/Water Vapor Atmosphere at 500 °C

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