Anisotropy in the electrical properties of zirconium doped α -Fe2O3 single crystals

Benjelloun, Driss; Bonnet, Jean-Pierre; Doumerc, Jean‐Pierre; Launay, J.C.; Onillon, Marc

doi:10.1016/0254-0584(88)90054-5

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…The interpretation of hematite transport data is often confounded by polycrystalline or impure natural and synthetic samples. 57,58 Of most importance, in our view, is the accurate determination of the sample composition regarding impurities or vacancies that may affect electronic properties. Further, measurements are commonly made at elevated temperatures due to the high resistivity of the material.…”

Section: The Journal Of Physical Chemistry Lettersmentioning

confidence: 99%

“…At ambient conditions, hematite is a canted antiferromagnet that crystallizes in a distorted hexagonal structure ( R 3̅ c space group, a = 5.035 Å, c = 13.75 Å), with basal planes of Fe atoms separated by hexagonal close-packed oxygen layers. The interpretation of hematite transport data is often confounded by polycrystalline or impure natural and synthetic samples. , Of most importance, in our view, is the accurate determination of the sample composition regarding impurities or vacancies that may affect electronic properties. Further, measurements are commonly made at elevated temperatures due to the high resistivity of the material. , …”

mentioning

confidence: 99%

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Unravelling Small-Polaron Transport in Metal Oxide Photoelectrodes

Rettie

Chemelewski

Emin

et al. 2016

J. Phys. Chem. Lett.

242

264

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Transition-metal oxides are a promising class of semiconductors for the oxidation of water, a process that underpins both photoelectrochemical water splitting and carbon dioxide reduction. However, these materials are limited by very slow charge transport. This is because, unlike conventional semiconductors, material aspects of metal oxides favor the formation of slow-moving, self-trapped charge carriers: small polarons. In this Perspective, we seek to highlight the salient features of small-polaron transport in metal oxides, offer guidelines for their experimental characterization, and examine recent transport studies of two prototypical oxide photoanodes: tungsten-doped monoclinic bismuth vanadate (W:BiVO4) and titanium-doped hematite (Ti:α-Fe2O3). Analysis shows that conduction in both materials is well-described by the adiabatic small-polaron model, with electron drift mobility (distinct from the Hall mobility) values on the order of 10(-4) and 10(-2) cm(2) V(-1) s(-1), respectively. Future directions to build a full picture of charge transport in this family of materials are discussed.

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Section: The Journal Of Physical Chemistry Lettersmentioning

confidence: 99%

mentioning

confidence: 99%

Unravelling Small-Polaron Transport in Metal Oxide Photoelectrodes

Rettie

Chemelewski

Emin

et al. 2016

J. Phys. Chem. Lett.

242

264

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show abstract

“…The ionic radii of Ti 4+ (60 pm) and Cr 3+ (61 pm) are similar, leading to a negligible change in the lattice for this substitution [54]. A similar phenomenon can be observed for Zr + etching, where a Zr 4+ ion could substitute for a Fe 3+ ion present in a crystalline lattice, e.g., Fe 2 O 3 [55,56].…”

Section: Structural and Chemical Analyses Of Etched Couponsmentioning

confidence: 59%

Surface Modification of 304L Stainless Steel and Interface Engineering by HiPIMS Pre-Treatment

et al. 2022

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A clean and defect-free substrate/coating interface is required to guarantee good adhesion of coatings under service conditions. For this purpose, an etching pre-treatment using High-Power Impulse Magnetron Sputtering (HiPIMS) was performed to modify the surface of 304L stainless steel. The effect of three etching procedures on the substrate properties, such as corrosion resistance and adhesion, was investigated with unprecedented spatial resolution and spectroscopic details. Glancing angle X-ray diffraction showed modification in phase content but no neoformation after steel etching. X-ray photoelectron spectroscopy confirmed the presence of etchant species (6–7 at.%) on the extreme surface of the substrate. Transmission Electron Microscopy and Atomic Probe Tomography showed that the interface was less than a few nanometers wide. Polarization curves in a nitric acid solution at boiling temperature showed, for the first time, that the Ti+ and Zr+ etchings decreased the corrosion current density compared to the untreated original surface. Scratch-test measurements indicated better substrate/coating adhesion using HiPIMS metal ion etching. Electrochemical characterization revealed that Zr etching and thin coating improve the anti-corrosion properties of stainless steel in strong nitric acid conditions.

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“…Hematite has had limited success as a PEC material for several reasons, however. As a pure-phase material, it is a known Mottinsulator, which means that, though charge separation occurs, charge transport properties are poor [68,75,81]; typically synthesized as low quality polycrystalline films, it exhibits high recombination rates due to crystal grain boundaries and unordered oxygen vacancies [86]; it exhibits anisotropic conductivity, wherein conductivity along the (001) plane is four orders of magnitude higher than in the [001] direction [45,55,81], which is again an issue for polycrystalline films; and the conduction band edge is typically ~0.2 eV too positive for unbiased hydrogen evolution [87]. Group IV and III-V: There are many possible binary, ternary, and quaternary combinations of group III-V and IV elements that yield semiconductors with interesting…”

Section: Types Of Pec Cells/materials and Background Literaturementioning

confidence: 99%

Comparison of a-Fe2O3 electrodes grown by direct plasma and thermal oxidation of iron for photoelectrochemical water splitting.

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Anisotropy in the electrical properties of zirconium doped α -Fe2O3 single crystals

Cited by 3 publications

References 8 publications

Unravelling Small-Polaron Transport in Metal Oxide Photoelectrodes

Unravelling Small-Polaron Transport in Metal Oxide Photoelectrodes

Surface Modification of 304L Stainless Steel and Interface Engineering by HiPIMS Pre-Treatment

Comparison of a-Fe2O3 electrodes grown by direct plasma and thermal oxidation of iron for photoelectrochemical water splitting.

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