Effect of magnetic field on the growth of α-Fe2O3 thin films by atomic layer deposition

Nilsen, Ola; Lie, Martin; Foss, Sean Erik; Fjellvåg, Helmer; Kjekshus, Arne

doi:10.1016/j.apsusc.2003.10.045

Cited by 55 publications

(42 citation statements)

References 43 publications

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“…In selected cases, an Al 2 O 3 ALD technique was used to deposit an additional catalytic support layer. The Al 2 O 3 ALD used three ALD cycles comprised of alternating exposures to trimethyl aluminum and water vapors to deposit *0.4 nm of Al 2 O 3 [25][26][27]. Finally, the Co 3 O 4 ALD coating was performed using 5-20 ALD cycles comprised of alternating exposures to bis(cyclopentadienyl)cobalt (II) and ozone.…”

Section: Catalyst Preparationmentioning

confidence: 99%

Fischer–Tropsch Synthesis: Preconditioning Effects Upon Co-Containing Promoted and Unpromoted Catalysts

et al. 2012

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In the preparation and evaluation of FischerTropsch (FT) catalysts, active catalysts formed by both incipient wetness impregnation (IWI) and atomic layer deposition (ALD) of major components were demonstrated. ALD-deposited Co on a silica support was more effective than a similar catalyst deposited upon a support of ALD-deposited Al 2 O 3 on silica. The addition of Co reduction promoters including Pt, Ir and Ru using either ALD or IWI has been shown to strongly affect the catalyst pre-conditioning step. CO conversion results were consistent with previously reported Temperature Programmed Reduction X-ray Absorption Near-edge Structure/Extended X-ray Absorption Fine Structure Spectroscopy (TPR-XANES/EXAFS) experiments observing the nature of chemical transformations occurring during the activation of cobalt-based FT catalysts in hydrogen. Specifically, there exists a 2-step reduction process involving Co 3 O 4 to CoO and CoO to Co 0 transformations. The extent of catalyst preconditioning was strongly affected by the reduction temperature (with 400°C preferred) and the loading of the promoter. This was demonstrated using a continuous-flow catalytic-bed unit with a 2:1 molar blend of H 2 :CO, at temperatures ranging from about 260 to 300°C, pressures averaging 1.3 MPa (190 psia), and gas space velocities about 24 NL/h-g.

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Section: Catalyst Preparationmentioning

confidence: 99%

Fischer–Tropsch Synthesis: Preconditioning Effects Upon Co-Containing Promoted and Unpromoted Catalysts

et al. 2012

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“…A variety of different methods has been used to deposit iron oxide thin films, e.g., sputtering, [4] sol-gel, [5] aqueous chemical growth, [3] molecular beam epitaxy (MBE), [8] CVD, [9,10] and ALD. [11][12][13][14] There are also numerous reports of nanostructured iron oxide. [3,[15][16][17][18] Despite all reports of nanostructured materials, it is inherently difficult to fabricate arrays in a well-ordered pattern.…”

Section: Introductionmentioning

confidence: 99%

Atomic Layer Deposition of Iron Oxide Thin Films and Nanotubes using Ferrocene and Oxygen as Precursors

Rooth

Johansson

Kukli

et al. 2008

Chemical Vapor Deposition

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Thin films and nanotubes of iron oxide are deposited using atomic layer deposition (ALD) on Si(100) and anodic aluminum oxide (AAO), respectively. Ferrocene, Fe(Cp) 2 , and oxygen are used as precursors. Successful depositions are carried out in the temperature range 350-500 -C on Si(100), while all depositions on AAO are made at 400 -C. The growth per cycle values are around 0.14 nm on Si(100) in the temperature range 350-500 -C and 0.06 nm on AAO. Below 500 -C, the iron oxide crystallizes as a phase mixture on both types of substrates. One of the phases is identified as the rhombohedral Fe 2 O 3 phase (hematite), but the second phase cannot be unambiguously identified. Above 500 -C, only phase pure hematite is detected. For deposition of nanotubes, in-house made AAO membranes are used, having an aspect ratio of 30. By etching of the AAO membranes after deposition, free-standing nanotubes retaining the order of the AAO template can be fabricated.

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“…In this case, the ferromagnetic hematite has been considered an important potential material for technological uses, primarily as thin film sensors and photoelectrodes [10][11][12][13][14].…”

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confidence: 99%

Hematite thin films: growth and characterization

et al. 2006

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We have grown hematite (α − Fe 2 O 3 ) thin films on stainless steel and (001)-silicon single-crystal substrates by RF magnetron sputtering process in argon atmosphere at substrate temperatures from 400 to 800 • C. Conversion Electron Mössbauer (CEM) spectra of the sample grown on stainless steel at 400 • C exhibit values for hyperfine parameter characteristic of bulk hematite phase in the weak ferromagnetic state. Also, the relative line intensity ratio suggests that the magnetization vector of the polycrystalline film is aligned preferentially parallel to the surface. The X-ray diffraction (XRD) pattern of the polycrystalline thin film grown on steel substrates also corresponds to α − Fe 2 O 3 . The samples were also analyzed by Atomic Force Microscopy (AFM), those grown on stainless steel reveal a morphology consisting of columnar grains with random orientation, given the inhomogeneity of the substrate surface.

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Effect of magnetic field on the growth of α-Fe2O3 thin films by atomic layer deposition

Cited by 55 publications

References 43 publications

Fischer–Tropsch Synthesis: Preconditioning Effects Upon Co-Containing Promoted and Unpromoted Catalysts

Fischer–Tropsch Synthesis: Preconditioning Effects Upon Co-Containing Promoted and Unpromoted Catalysts

Atomic Layer Deposition of Iron Oxide Thin Films and Nanotubes using Ferrocene and Oxygen as Precursors

Hematite thin films: growth and characterization

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