Iron oxides are chemical compounds A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds composed of iron Iron is the most common element in the earth as a whole, and the fourth most common in the Earth's crust. It is produced as a result of stellar fusion in high-mass stars, and it is the heaviest stable element produced by stellar fusion because the fusion of iron is the last nuclear fusion reaction that is exothermic. Iron is the most widely used and oxygen Oxygen (pronounced /ˈɒksɨdʒɨn/, OK-si-jin, from the Greek roots ὀξύς (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly. Altogether, there are sixteen known iron oxides An oxide is a chemical compound containing at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon monoxide and carbon dioxide. Even materials that are and oxyhydroxides.[1]
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Oxides
- FeO, iron(II) oxide Iron oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted iron, is one of the iron oxides. It is a black-colored powder with the chemical formula Fe , (wüstite Wüstite was named for Fritz Wüst , a German metallurgist and founding director of the Kaiser-Wilhelm-Institut für Eisenforschung (presently Max Planck Institute for Iron Research GmbH))
- Fe3O4, iron(II,III) oxide, (magnetite Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part wüstite (FeO) and one part hematite (Fe2O3). This)
- Fe2O3, iron(III) oxide Iron oxide is the inorganic compound with the formula Fe2O3. It is of one of the three main oxides of iron, the other two being FeO, which is rare, and Fe3O4, which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of the iron for the steel industry. Fe2O3 is paramagnetic, reddish brown, and, (hematite Hematite, also spelled as hæmatite, is the mineral form of iron oxide (Fe2O3), one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete solid solution at temperatures above 950°C)
- α-Fe2O3, hematite Hematite, also spelled as hæmatite, is the mineral form of iron oxide (Fe2O3), one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete solid solution at temperatures above 950°C
- β-Fe2O3
- γ-Fe2O3, maghemite Maghemite is a member of the family of iron oxides. It has the same structure as magnetite, that is, it is spinel ferrite and is also ferrimagnetic
- ε-Fe2O3
Hydroxides
- iron(II) hydroxide Iron hydroxide or ferrous hydroxide is a compound produced when iron(II) ions, from a compound such as iron(II) sulfate react with hydroxide ions. Iron(II) hydroxide itself is practically white, but even traces of oxygen impart it with a greenish tinge. If the solution was not deoxygenated and the iron reduced, the precipitate can vary in color (Fe(OH)2)
- iron(III) hydroxide (Fe(OH)3), (bernalite)
Oxide/hydroxides
Main article: iron(III) oxide-hydroxide A number of species are dubbed iron oxide-hydroxide. These chemicals are oxide-hydroxides of iron, and may occur in anhydrous (Fe- goethite Goethite (FeO), (pronounced: "Gertite" /ˈgɝtaɪt/) named after the German polymath Johann Wolfgang von Goethe, is an iron bearing oxide mineral found in soil and other low-temperature environments. Goethite has been well known since prehistoric times for its use as a pigment. Evidence has been found of its use in paint pigment samples (α-FeOOH),
- akaganéite Akaganéite is an iron oxide-hydroxide / chloride mineral with formula: Fe3+O(OH,Cl) e.g; β-FeO(OH). It is formed by the weathering of pyrrhotite (Fe1-xS). Nickel also has been reported in the structure. It has a monoclinic crystal structure, a metallic luster and a brownish yellow streak. It is named after the Akagane mine in Iwate, Japan, in (β-FeOOH),
- lepidocrocite (γ-FeOOH),
- feroxyhyte Feroxyhyte is an oxide/hydroxide of iron, δ-Fe3+O. Feroxyhyte crystallizes in the hexagonal system. It forms as brown rounded to concretionary masses. Feroxyhyte is opaque, magnetic, has a yellow streak, and has a relative density of 4.2 (δ-FeOOH),
- ferrihydrite Ferrihydrite is a widespread hydrous ferric oxyhydroxide mineral at the earth's surface, and a likely constituent in extraterrestrial materials. It forms in several types of environments, from freshwater to marine systems, aquifers to hydrothermal hot springs and scales, soils, and areas affected by mining. It can be precipitated directly from (Fe5HO8·4H2O approx.)
- high-pressure FeOOH
- schwertmannite Schwertmannite is an iron-oxyhydroxysulfate mineral with an ideal chemical formula of Fe8O86(S
Uses
A prehistorical painting (Lascaux Lascaux is the setting of a complex of caves in southwestern France famous for its Paleolithic cave paintings. The original caves are located near the village of Montignac, in the Dordogne département. They contain some of the best-known Upper Paleolithic art. These paintings are estimated to be 17,000 years old. They primarily consist of) created with locally-available pigments: red and yellow ochres Ochre or Ocher is term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as Red ochre. The more rarely used terms Purple ochre and Brown ochre also exist for variant hues. Because of these other hues, the color Ochre is[1]The most industrially-important iron ores Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite , hematite (Fe2O3), goethite (FeO(OH)), limonite (FeO(OH).n(H2O)) or siderite (FeCO3) are chemically iron oxides.
Some iron oxides are widely used in ceramic A ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous . Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the non- applications, particularly in glazing Glaze is a layer or coating of a vitreous substance which has been fired to fuse to a ceramic object to color, decorate, strengthen or waterproof it. Many metal oxides provide the colors in glazes after being fired at high temperatures.
Iron oxides yield pigments A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light (see iron oxide pigments Categories: Iron compounds | Oxides | Inorganic pigments | Cosmetic chemicals ). Natural iron oxides pigments are called ochres Ochre or Ocher is term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as Red ochre. The more rarely used terms Purple ochre and Brown ochre also exist for variant hues. Because of these other hues, the color Ochre is. Many classic paint colors, such as raw and burnt siennas Sienna is a form of limonite clay most famous in the production of oil paint pigments. Its yellow-brown colour comes from ferric oxides contained within. As a natural pigment, it was one of the first pigments to be used by humans, and is found in many cave paintings and umbers, are iron-oxide pigments. These pigments have been used in art since the earliest prehistoric art known, the cave paintings Cave paintings are paintings on cave walls and ceilings, and the term is used especially for those dating to prehistoric times. The earliest known European cave paintings date to Aurignacian, some 32,000 years ago. The purpose of the paleolithic cave paintings is not known. The evidence suggests that they were not merely decorations of living at Lascaux Lascaux is the setting of a complex of caves in southwestern France famous for its Paleolithic cave paintings. The original caves are located near the village of Montignac, in the Dordogne département. They contain some of the best-known Upper Paleolithic art. These paintings are estimated to be 17,000 years old. They primarily consist of and nearby sites. Iron (III) oxide is typically used.
Iron pigments are also widely used in the cosmetic field. They are considered to be nontoxic, moisture resistant, and nonbleeding. Iron oxides graded safe for cosmetic use are produced synthetically in order to avoid the inclusion of ferrous or ferric oxides, and impurities normally found in naturally occurring iron oxides. Typically, the iron(II) oxide pigment is black, while the iron(III) oxide is red or rust-colored. (Iron compounds other than oxides can have other colors.)
Black oxide Black oxide or blackening is a conversion coating for ferrous materials, copper and copper based alloys, zinc, powdered metals, and silver solder. It is used to add mild corrosion resistance and for appearance. To achieve maximum corrosion resistance the black oxide must be impregnated with oil or wax. One of its advantages over other coatings is converts ferrous materials into magnetite for corrosion resistance purposes. A grade of hematite called MIO (micaceous iron oxide) is used as anti-corrosion paint (many bridges, Eiffel tower).
Iron oxide is used in magnetic recording Magnetic storage and magnetic recording are terms from engineering referring to the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to store data and is a form of non-volatile memory. The information is accessed using one or more read/write heads. As of 2009, magnetic, recording sound, pictures, video and computer data on plastic tape or floppy disks A floppy disk is a data storage medium that is composed of a disk of thin, flexible magnetic storage medium encased in a square or rectangular plastic shell.
Iron oxides are used as contrast agent in Magnetic Resonance Imaging Magnetic resonance imaging , or nuclear magnetic resonance imaging (NMRI), is primarily a medical imaging technique most commonly used in radiology to visualize detailed internal structure and limited function of the body. MRI provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does, making, to shorten proton relaxation times In nuclear magnetic resonance spectroscopy and magnetic resonance imaging (MRI) the term relaxation describes several processes by which nuclear magnetization prepared in a non-equilibrium state return to the equilibrium distribution. In other words, relaxation describes how fast spins "forget" the direction in which they are oriented, (T1, T2 and T2*). The superparamagnetic contrast agents are composed of a water insoluble crystalline magnetic core, usually magnetite (Fe3O4) or maghemite (γ-Fe2O3). The mean core diameter ranges from 4 to 10 nm. This crystalline core is often surrounded by a layer of dextran Dextran is a complex, branched glucan composed of chains of varying lengths (from 10 to 150 kilodaltons). It is used medicinally as an antithrombotic (anti-platelet), to reduce blood viscosity, and as a volume expander in anemia or starch derivatives Modified starch is prepared by treating physically, enzymatically or chemically starch, changing the properties of the starch. Modified starches are used in all starch applications: in food products for example as a thickening agent, stabilizer or emulsifier, in pharmaceuticals as disintegrant, in paper as a binder and in many other applications. The total size of the particle is expressed as the mean hydrated particle diameter. USPIO, Ultrasmall Superparamagnetic Iron Oxide nanoparticles, which usually have single crystal cores, have a mean hydrated particle diameter less than 50 nm.
They may also be used in electrochromic Electrochromism is the phenomenon displayed by some materials of reversibly changing color when a burst of charge is applied. Various types of materials and structures can be used to construct electrochromic devices, depending on the specific applications paints Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film.
Combined with aluminium powder, iron oxide forms thermite Thermite is a pyrotechnic composition of a metal powder and a metal oxide, which produces an aluminothermic reaction known as a thermite reaction. Most varieties are not explosive, but can create short bursts of extremely high temperatures focused on a very small area for a short period of time.
The iron oxide cycle (Fe3O4/FeO) is a two-step thermochemical In thermodynamics and physical chemistry, thermochemistry is the study of the energy evolved or absorbed in chemical reactions and any physical transformations, such as melting and boiling. Thermochemistry, generally, is concerned with the energy exchange accompanying transformations, such as mixing, phase transitions, chemical reactions, and process used for hydrogen production Hydrogen production is usually the term for the industrial methods for generating hydrogen. Currently the dominant technology for direct production is steam reforming from hydrocarbons. Hydrogen is also produced as a byproduct of other processes and managed with hydrogen pinch. Many other methods are known including electrolysis and thermolysis.
Properties
- Iron(II) oxide Iron oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted iron, is one of the iron oxides. It is a black-colored powder with the chemical formula Fe (FeO) or ferrous oxide is also known as wüstite Wüstite was named for Fritz Wüst , a German metallurgist and founding director of the Kaiser-Wilhelm-Institut für Eisenforschung (presently Max Planck Institute for Iron Research GmbH) in its mineral form. As a powder A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material. In particular, powders refer to those granular materials that have this black oxide can cause explosions An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive". Subsonic shock waves are created by as it readily ignites Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame. Fuels of interest often include organic compounds in the gas, liquid or.
- Iron(III) oxide Iron oxide is the inorganic compound with the formula Fe2O3. It is of one of the three main oxides of iron, the other two being FeO, which is rare, and Fe3O4, which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of the iron for the steel industry. Fe2O3 is paramagnetic, reddish brown, and (Fe2O3) or ferric oxide is also known as hematite Hematite, also spelled as hæmatite, is the mineral form of iron oxide (Fe2O3), one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete solid solution at temperatures above 950°C (alpha form) or maghemite Maghemite is a member of the family of iron oxides. It has the same structure as magnetite, that is, it is spinel ferrite and is also ferrimagnetic (gamma form) in its mineral form. As an industrial chemical it is commonly called rouge. Purified, it is used as a coating Coating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance. In other cases, in particular in printing processes and in magnetic audio and computer media. In a dry or alkaline environment, it can cause passivation and inhibit rust, yet it is also a major component of rust and dried blood.
- Iron(II,III) oxide (Fe3O4) or ferrous ferric oxide is also known as magnetite or lodestone in its mineral form, a major iron ore. Magnetite forms readily when iron oxidizes underwater, and so is often found inside tanks or below the waterline of ships.
References
- ^ a b Cornell, RM; Schwertmann, U (2003). The iron oxides: structure, properties, reactions, occurrences and uses. Wiley VCH. ISBN 3-527-30274-3.
External links
- Information from Nano-Oxides, Inc. on Fe2O3.
- http://chemed.chem.purdue.edu/demos/demosheets/12.3.html
- http://minerals.usgs.gov/minerals/pubs/commodity/iron_oxide/
Categories: Iron compounds | Oxides | Iron oxide pigments
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