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Curie Temperature
In physics and materials science, the Curie temperature (''T''C), or Curie point, is the temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism. The Curie temperature is named after Pierre Curie, who showed that magnetism is lost at a critical temperature. The force of magnetism is determined by the magnetic moment, a dipole moment within an atom that originates from the angular momentum and spin of electrons. Materials have different structures of intrinsic magnetic moments that depend on temperature; the Curie temperature is the critical point at which a material's intrinsic magnetic moments change direction. Permanent magnetism is caused by the alignment of magnetic moments, and induced magnetism is created when disordered magnetic moments are forced to align in an applied magnetic field. For example, the ordered magnetic moments (ferromagnetic, Figure 1) change and become disordered ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function (mathematics), function assigning a Euclidean vector, vector to each point of space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust, being mainly deposited by meteorites in its metallic state. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching , about 500 °C (900 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age. In the modern world, iron alloys, such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yttrium Iron Garnet
Yttrium iron garnet (YIG) is a kind of synthetic garnet, with chemical composition , or Y3Fe5O12. It is a ferrimagnetic material with a Curie temperature of 560 K. YIG may also be known as yttrium ferrite garnet, or as iron yttrium oxide or yttrium iron oxide, the latter two names usually associated with powdered forms. Production Several methods are utilized for synthesis of yttrium iron garnet each with their pros and cons. The solid-state reaction method is a traditional approach for YIG synthesis, involving the high-temperature firing of a mixture of yttrium and iron oxides. This cost-effective technique can produce pure YIG crystals but requires careful control of temperature and atmosphere to prevent impurities. Liquid phase epitaxy (LPE) is another key method, especially for creating thin YIG films with excellent uniformity. Ideal for optical and microwave devices, LPE enables precise film growth on substrates. However, its high equipment costs and complex proced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable, unalloyed metallic form. This means that copper is a native metal. This led to very early human use in several regions, from . Thousands of years later, it was the first metal to be smelted from sulfide ores, ; the first metal to be cast into a shape in a mold, ; and the first metal to be purposely alloyed with another metal, tin, to create bronze, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron(II,III) Oxide
Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe3O4. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe2O3) which also occurs naturally as the mineral hematite. It contains both Fe2+ and Fe3+ ions and is sometimes formulated as FeO ∙ Fe2O3. This iron oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is Ferrimagnetism, ferrimagnetic, but is sometimes incorrectly described as Ferromagnetism, ferromagnetic. Its most extensive use is as a black pigment (see: Mars Black (pigment), Mars Black). For this purpose, it is synthesized rather than being extracted from the naturally occurring mineral as the particle size and shape can be varied by the method of production. Preparation Heated iron metal interacts with steam to form iron oxide and hydrogen gas. :3Fe + 4H2O->Fe3O4 + 4H2 Under Hypox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron(III) Oxide
Iron(III) oxide or ferric oxide is the inorganic compound with the formula . It occurs in nature as the mineral hematite, which serves as the primary source of iron for the steel industry. It is also known as red iron oxide, especially when used in pigments. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (), which also occurs naturally as the mineral magnetite. Iron(III) oxide is often called rust, since rust shares several properties and has a similar composition; however, in chemistry, rust is considered an ill-defined material, described as hydrous ferric oxide. Ferric oxide is readily attacked by even weak acids. It is a weak oxidising agent, most famously when reduced by aluminium in the thermite reaction. Structure can be obtained in various polymorphs. In the primary polymorph, α, iron adopts octahedral coordination geometry. That is, each Fe center is bound to six oxygen ligands. In t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europium(II) Oxide
Europium(II) oxide (EuO) is a chemical compound which is one of the oxides of europium. In addition to europium(II) oxide, there is also europium(III) oxide and the mixed valence europium(II,III) oxide. Preparation Europium(II) oxide can be prepared by the Redox, reduction of europium(III) oxide with elemental europium at 800 °C and subsequent vacuum distillation at 1150 °C. :Eu2O3 + Eu → 3 EuO It is also possible to synthesize from the reaction of europium oxychloride and lithium hydride. :2 EuOCl + 2 LiH → 2 EuO + 2 LiCl + H2 In modern research, thin films can be manufactured by molecular beam epitaxy directly from europium atoms and oxygen molecules. These films have contamination of Eu3+ of less than 1%. Properties Europium(II) oxide is a violet compound as a bulk crystal and transparent blue in thin film form. It is unstable in humid atmosphere, slowly turning into the yellow europium(II) hydroxide hydrate and then to white europium(III) hydroxide. EuO cryst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic
Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is notoriously toxic. It occurs naturally in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. It has various Allotropes of arsenic, allotropes, but only the grey form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is also a common n-type dopant in semiconductor electronic devices, and a component of the III–V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the increasing recognition of the persistent tox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromium(IV) Oxide
Chromium dioxide or chromium(IV) oxide is an inorganic compound with the formula CrO2. It is a black synthetic magnetic solid. It once was widely used in magnetic tape emulsion. With the increase in popularity of CDs and DVDs and more recently digital media, the use of chromium(IV) oxide has declined. However, it is still used in data tape applications for enterprise-class storage systems. It is still considered by many oxide and tape manufacturers to have been one of the best magnetic recording particulates ever invented. Preparation and basic properties CrO2 was first prepared by Friedrich Wöhler by decomposition of chromyl chloride. Acicular chromium dioxide was first synthesized in 1956 by Norman L. Cox, a chemist at E.I. DuPont, by decomposing chromium trioxide in the presence of water at a temperature of and a pressure of 200 MPa. The balanced equation for the hydrothermal synthesis is: :3 CrO3 + Cr2O3 → 5 CrO2 + O2 The magnetic crystal that forms is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimony
Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name Kohl (cosmetics), kohl. The earliest known description of this metalloid in the West was written in 1540 by Vannoccio Biringuccio. China is the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods for refining antimony from stibnite are Roasting (metallurgy), roasting followed by carbothermic reaction, reduction with carbon, or direct reduction of stibnite with iron. The most common applications for metallic antimony are in alloys with lead and tin, which have improved properties for solders, Bullet, bullets, and plain bearings. It improves the rigidity of lead-alloy pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismanol
Bismanol is a magnetic alloy of bismuth and manganese (manganese bismuthide) developed by the US Naval Ordnance Laboratory. History Bismanol, a permanent magnet made from powder metallurgy of manganese bismuthide, was developed by the US Naval Ordnance Laboratory in the early 1950s – at the time of invention it was one of the highest coercive force permanent magnets available, at 3000 oersteds. Coercive force reached 3650 oersteds and magnetic flux density 4800 by the mid 1950s. The material was generally strong, and stable to shock and vibration, but had a tendency to chip. Slow corrosion of the material occurred under normal conditions. The material was used to make permanent magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, c ...s for use in small electric motors. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dysprosium
Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it is found in various minerals, such as xenotime. Naturally occurring dysprosium is composed of seven isotopes, the most abundant of which is 164Dy. Dysprosium was first identified in 1886 by Paul Émile Lecoq de Boisbaudran, but it was not isolated in pure form until the development of ion-exchange techniques in the 1950s. Dysprosium is used to produce neodymium-iron-boron (NdFeB) magnets, which are crucial for electric vehicle motors and the efficient operation of wind turbines. It is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility () in data-storage applications, and as a component of Terfenol-D (a magnetostrictive material). Soluble dyspr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
