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The structure of hematite ( -Fe2O3) (001) surfaces in aqueous media: Scanning tunneling microscopy and resonant tunneling calculations of coexisting O and Fe terminations C ARRICK M. E GGLESTON, 1, *A NDREW G. S TACK, 1 K EVIN M. R OSSO, 2 S TEVEN R. H IGGINS, 1 A NGELA M. B ICE, 1 S TEVEN W. B OESE, 1
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Scanning tunneling microscope (STM) images and scanning tunneling spectroscopy (STS) spectra of hematite (α-Fe 2 O 3) surfaces were calculated using ab-initio methods, not only to interpret experimentally collected STM data, but also to gain insight into atomic level changes in electronic structure that are associated with heterogeneous surface reactions.
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There are several types of iron oxides with different oxidation numbers and coordination structures, 1 with the iron oxides of α-Fe 2 O 3 (Hematite), γ-Fe 2 O 3 (maghemite), and Fe 3 O 4 (magnetite) attracting increasing attention in chemical, medical, and electronic industries for applications such as catalysts, photoanodes, drug delivery, sensors, and …
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Crystal structure of hematite. (a) Ball and stick and (b) coordination polyhedral representations of the atomic arrangement within a hexagonal unit cell (thin black line), with a = 5.0380 Å and c ...
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Hematite, with the chemical formula Fe2O3, exhibits several chemical properties that contribute to its characteristics and behavior. Here are some of the key chemical properties of hematite: 1. Composition: Hematite consists of iron (Fe) and oxygen (O) atoms, with two iron atoms … See more
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Hematite is the most important ore of iron, and it has been used by people as a pigment for at least 40,000 years. Learn about the uses and properties of the mineral hematite.
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Scanning tunneling microscopy (STM) is used to study the structure of {001} hematite single-crystal surfaces. STM images taken at negative sample bias consistently show a hexagonal array ofatomic sites with 3-Å periodicity, as expected for the surface O array and in agreement with photoelectron spectroscopy studies of hematite surfaces after O 2 and H 2 O …
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Oxides class Hematite group Mineral name: Hematite Formula: Fe2O3 Classification: Oxides – Hematite group Crystal system: Trigonal Crystal class (Hermann-Mauguin): -3m - Hexagonal Scalenohedral Space group: R-3c Crystal data from Blake R. L., Hessevick R. E., Zoltai T., Finger L. W. (1966) Note: The color code used in these models is …
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U(VI) doped hematite was synthesized and exposed to two different organic reductants with E(0) of 0.23 and 0.70 V. A combination of HAADF-TEM and EXAFS provided evidence that uranium was incorporated in hematite in uranate, likely octahedral coordination. XPS indicated that structurally incorporated …
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A reniform (kidney-shaped) or botryoidal variety of hematite. The internal structure of the kidney-shaped nodules is usually concentric and radiating. Manganese-bearing Hematite: Martite: The name given for hematite pseudomorphs after magnetite, formed under conditions of increasing oxygen fugacity.
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Atomic-Scale Structure of the Hematite α‑Fe 2O 3 ... structure is a prerequisite, and there remain many important metal oxides where this basic knowledge does not exist. To date, most surface-science studies of α-Fe 2 O 3 have utilized thin-film samples grown epitaxially on a …
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The hematite structure has two formula units per unit cell, the trigonal-hexagonal and the primitive rhombohedral unit cells (Fig. 2). 33 It contains iron and oxygen atoms arranged in a trigonal ...
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Crystal Structure of Hematite. Hematite formula is Fe 2 O 3, is a simple iron III oxide. Hematite is a member of the trigonal crystal system, exhibiting a large variety of forms. As discrete forms, hematite may occur as small plates or thin splinters. As larger masses, it may be botryoidal, mammilary, reniform, oolitic, radiating, stalactitic ...
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Download scientific diagram | Crystal structure of (a) wustite (FeO), (b) magnetite (Fe 3 O 4 ) and (c) hematite (α-Fe 2 O 3 ). from publication: Grain Boundary in Oxide Scale During High ...
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The hematite structure has two formula units per unit cell, the trigonal-hexagonal and the primitive rhombohedral unit cells (Fig. 2). 33 It contains iron and oxygen atoms arranged in a...
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Hematite is an iron-oxide mineral of the Oxides and Hydroxides group, with structural formula [alpha-Fe 2 O 3]. The structure is similar to that of corundum, and consists essentially of a …
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Fig. 1.-Curves showing values of the structure factor S for planes with h + k + 1 odd; the numbers on each curve signify values of h - k, k-Z and 2 - h; for example, 322 gives values of S for all planes with It + k + I odd and with h - k = -4, k - 1 = 2,Hnd 1 - h = 2. - "THE CRYSTAL STRUCTURES OF HEMATITE AND CORUNDUM"
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We present a computational study of the electronic structure of excitons in hematite Fe2O3 using density functional theory (DFT) and time-dependent DFT theory. Excitons resulting from solar light absorption are precursors to photogenerated charge carriers, which are the active species in solar-to-fuel redox conversions. Upon vertical excitation, the lowest energy exciton …
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The hematite structure can be described in mineralogical terms as being composed of gibbsite-type octahedral layers stacked six-high nor-mal to the c-axis. Subsequent octahedral layers are reiated to each other b1'a combination of (1) inversion of all octahedra through the centers of
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Introduction Hematite, Fe203, and corundum, A&&, form crystals which have been assigned,' on the basis of observed face development, to the holohedral class of the rhombohedral system, with the rhombohedral angle a: equal to 85' 42' and 85' 42$', respectively. Spectrometric measurements have been made2 of the reflection of X-rays from three faces of ruby, A1403, …
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Hematite's Streak: All specimens of hematite will produce a reddish streak. The streak of a mineral is its color in powdered form when scraped across a streak plate (a small piece of unglazed porcelain used to produce a small amount of …
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Hematite (α-Fe 2 O 3) nanoparticles have been successfully synthesized via two methods: (1) polyol and (2) precipitation in water.The influence of synthesis methods on the crystalline structure, morphological, optical, magnetic and electrical properties were investigated using X-ray diffraction, RAMAN spectroscopy, scanning electron microscopy, transmission …
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Hematite is an iron-oxide mineral of the Oxides and Hydroxides group, with structural formula [alpha-Fe 2 O 3]. The structure is similar to that of corundum, and consists essentially of a …
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Hematite has a corundum (Al 2 O 3) structure (space group, Z = 6) and can be indexed with rhombohedral or hexagonal (Figure 1) unit cells. Here we refer all directions and planes to the hexagonal cell. Hematite consists of …
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Atomic structure of a mono-dispersive hematite (α-Fe 2 O 3) nanocube (01 1 ¯ 2) surface was determined with synchrotron X-ray diffraction.The α-Fe 2 O 3 nanocubes were prepared through a hydrothermal process and a single layer of nanocubes was deposited on a silicon substrate with a drop cast method. The alignment of nanocubes with their {01 1 ¯ 2} …
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The crystal structure of hematite has been shown to be rhombohedral 3 but for convenience it is considered here to consist of a close-packed hexagonal arrange- ment of oxygen 02- ions. The unit cell, containing six formula units, is given by a = 5.0298~,, c = 13.753A. Magnetite has an inverse spinel structure 4 with unit cell ...
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hematite and iron glance into maghemite in an oxidizing atmosphere; hematite structure seems to aid in retaining magnetic properties in an oxidizing atmosphere. Ferromagnetic Fe203 is designated as y -Fe203 in contrast to non-magnetic or normal a -Fe203. The elemental content is the same as that of hematite but the crystalline structure differs.
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A list of synthesized hematite with their structure properties and HMIs adsorption capacities is summarized in Table 1. The results of laboratory experiments may reflect the effectiveness of hematite under natural conditions. Kefeni et al. investigated the stability and removal capacity of synthesized hematite for HMIs from acid mine drainage.
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General Hematite Information : Chemical Formula: Fe2O3 : Composition: Molecular Weight = 159.69 gm ... Zoltai T, Finger L W, American Mineralogist, 51 (1966) p.123-129, Refinement of the hematite structure . View Additional jPOWD Structure files for Hematite : Physical Properties of Hematite : Cleavage: None : Color: Reddish gray, Black ...
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Hematite is the oldest known iron oxide mineral. Formula Fe2O3. it is the most important ore of iron because of its high iron content and its abundance. ... Crystal Structure: Hematite crystallizes in the trigonal crystal system, forming rhombohedral crystals. Its crystal structure consists of close-packed oxygen atoms with iron ions occupying ...
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the valence band is dominated by oxygen p states, hematite is generally considered to be a charge-transfer rather than a Mott-Hubbard insulator. There has been a considerable amount of experimental work on hematite, regarding its structural, magnetic, and electronic properties in bulk1–3,6–21 as well as in
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Hematite is rather variable in its appearance - it can be in reddish brown, ocherous masses, dark silvery-grey scaled masses, silvery-grey to black crystals, and dark-grey masses, to name a …
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Three-dimensional diffraction intensities were collected from a spherical single crystal of hematite, α-Fe 2 O 3, with a Buerger single-crystal diffractometer.The structure has been refined with a least-squares program, and the final structure gave an R-factor of 3.65 per cent.
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Iron oxides are particularly important because of their various applications and it exist in many form in nature including hematite (α-Fe 2 O 3), maghemite (γ-Fe 2 O 3) and magnetite (Fe 3 O 4) in which hematite being probably most common phase.Hematite (α-Fe 2 O 3) is a metal oxide n-type semiconductor with a band gap of ∼2.1eV which has a potential …
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2.1 Crystal Structure. Hematite has a corundum (Al 2 O 3) structure (space group, Z = 6) and can be indexed with rhombohedral or hexagonal (Figure 1) unit cells. Here we refer all directions and planes to the hexagonal cell. Hematite consists of hexagonally close packed O 2− arrays stacked along the [001
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Hematite. Comments: Black, platy hematite and minor white magnesite. Location: Brumado, Bahia, Brazil. Scale: 9 x 4.5 cm. © Fabre Minerals
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