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F-Center
An F-center or color center or Farbe center (from the original German ''Farbzentrum'', where ''Farbe'' means ''color'' and ''zentrum'' means ''center'') is a type of crystallographic defect in which an anionic Vacancy defect, vacancy in a crystal lattice is occupied by one or more unpaired electrons. Electrons in such a vacancy in a crystal lattice tend to absorb light in the visible spectrum such that a material that is usually Transparency (optics), transparent becomes colored. The greater the number of F centers, the more intense the color of the compound. F centers are a type of color center. This is used to identify many compounds, especially zinc oxide (yellow). History Before the discovery of point defects it was already known that some crystals can be discolored using various methods. In 1830 T.J. Pearsall discovered that fluorspar could be discolored using violet light. Thirty years later similar results were achieved by melting crystals together with a specific metal. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NaCl - F-center
Sodium chloride , commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral halite. In its edible form, it is commonly used as a condiment and food preservative. Large quantities of sodium chloride are used in many industrial processes, and it is a major source of sodium and chlorine compounds used as feedstocks for further chemical syntheses. Another major application of sodium chloride is deicing of roadways in sub-freezing weather. Uses In addition to the many familiar domestic uses of salt, more dominant applications of the approximately 250 million tonnes per year production (2008 data) include chemicals and de-icing.Westphal, Gisbert ''et al.'' (2002) "Sodium Chloride" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim . Chemical functions Salt is used, directly or indirectly, in the produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkali Metal Halide
Alkali metal halides, or alkali halides, are the family of inorganic compounds with the chemical formula MX, where M is an alkali metal and X is a halogen. These compounds are the often commercially significant sources of these metals and halides. The best known of these compounds is sodium chloride, table salt. Structure Most alkali metal halides crystallize with the face-centered cubic lattices. In this structure both the metals and halides feature octahedral coordination geometry, in which each ion has a coordination number of six. Caesium chloride, bromide, and iodide crystallize in a body-centered cubic lattice that accommodates coordination number of eight for the larger metal cation (and the anion also).Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. . Properties The alkali metal halides exist as colourless crystalline solids, although as finely ground powders appear white. They melt at high temperature, usually several hundred degrees to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacancy By Multiple Ionization In A Crystal
Vacancy or No Vacancy may refer to: Economics * Vacancy (economics) or ''job opening'', a position offered by a business that wishes to hire a worker * Vacancy (housing), unoccupied houses in a community Film and television * ''Vacancy'' (film), a 2007 American horror film * "Vacancy" (''Law & Order: Criminal Intent''), a 2006 television episode * "No Vacancy" (''Cagney & Lacey''), a 1987 television episode * No Vacancy, a fictional rock band in the 2003 film ''School of Rock'' * ''No Vacancy'' (1999 film) * ''No Vacancy'', a 2012 film also known as The Helpers Music Albums * ''Vacancy'' (album), a 2016 album by Bayside * ''Vacancy'' (EP), a 1999 EP by Joseph Arthur * '' No Vacancy – The Best of The Motels'', 1990 compilation album by The Motels Songs * "Vacancy" (song), a 2008 single by a Japanese-American singer Kylee * "Vacancy", by Joseph Arthur from ''Vacancy'' * "Vacancy", by Neil Young from unreleased album '' Homegrown'' * "Vacancy", by Harry Chapin from '' V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exciton
An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb's law, Coulomb force resulting from their opposite charges. It is an electrically neutral quasiparticle regarded as an elementary excitation primarily in condensed matter, such as Electrical insulation, insulators, semiconductors, some metals, and in some liquids. It transports energy without transporting net electric charge. An exciton can form when an electron from the valence band of a crystal is promoted in energy to the conduction band e.g., when a material absorbs a photon. Promoting the electron to the conduction band leaves a positively charged hole in the valence band. Here 'hole' represents the unoccupied quantum mechanical electron state with a positive charge, an analogue in crystal of a positron. Because of the attractive coulomb force between the electron and the hole, a bound state is formed, akin to that of the electron and proton in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ray
A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz () and wavelengths less than 10 picometers (), gamma ray photons have the highest photon energy of any form of electromagnetic radiation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray
An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ranging from 10 Nanometre, nanometers to 10 Picometre, picometers, corresponding to frequency, frequencies in the range of 30 Hertz, petahertz to 30 Hertz, exahertz ( to ) and photon energies in the range of 100 electronvolt, eV to 100 keV, respectively. X-rays were discovered in 1895 in science, 1895 by the German scientist Wilhelm Röntgen, Wilhelm Conrad Röntgen, who named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography is widely used in medical diagnostics (e.g., checking for Bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F3 Center In A Crystal
F3 or F03 may refer to: Computing * F3, a function key on a computer keyboard * F3 (language), the working name for JavaFX Script, a scripting language * Fat-Free Framework, a PHP web application framework Military * Douglas F-3 Havoc, a photographic reconnaissance plane * Douglas F3D Skyknight (later F-10 Skyknight), a Douglas twin engine, mid-wing jet fighter * F 3 Malmslätt, a former Swedish Air Force unit * Felixstowe F.3, a 1917 British First World War flying boat * Hannover F.3, a World War I German prototype escort fighter * HMS ''Cossack'' (F03), a 1937 British Royal Navy destroyer * HMS ''F3'', a British F class submarine * McDonnell F3H Demon (later F-3 Demon), a United States Navy carrier-based jet fighter * Mk F3 155mm, French self-propelled gun * RAF Tornado F3, a British fighter * USS ''F-3'' (SS-22), a United States Navy submarine * A future Japanese fighter jet (F-3 or F-X) based on the i3 conceptual jet fighter and Mitsubishi X-2 prototype T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F2 Center In A Crystal
F, or f, is the sixth letter of the Latin alphabet and many modern alphabets influenced by it, including the modern English alphabet and the alphabets of all other modern western European languages. Its name in English is ''ef'' (pronounced ), and the plural is ''efs''. History The origin of ⟨F⟩ is the Semitic letter '' waw'', which represented a sound like or . It probably originally depicted either a hook or a club. It may have been based on a comparable Egyptian hieroglyph such as that which represented the word ''mace'' (transliterated as ḥ(dj)): T3 The Phoenician form of the letter was adopted into Greek as a vowel, ''upsilon'' (which resembled its descendant ⟨ Y⟩ but was also the ancestor of the Roman letters ⟨ U⟩, ⟨ V⟩, and ⟨ W⟩); and, with another form, as a consonant, ''digamma'', which indicated the pronunciation , as in Phoenician. Latin ⟨F⟩, despite being pronounced differently, is ultimately descended from digamma and closely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sapphire
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. The name ''sapphire'' is derived from the Latin word ', itself from the Greek language, Greek word (), which referred to lapis lazuli. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called ruby, rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on the locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewellery, jewelry. They also may be created synthetically in laboratories for industrial or decorative purposes in large boule (crystal), crystal boules. Because of the remarkable hardness of sapphires 9 on the Mohs scale of miner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue John (mineral)
Blue John (also known as Derbyshire Spar) is a semi-precious mineral, a rare form of fluorite with bands of a purple-blue or yellowish colour. In the United Kingdom it is found only at Blue John Cavern and Treak Cliff Cavern at Castleton, Derbyshire, Castleton in Derbyshire. During the 19th century, it was mined for its ornamental value, and mining continues on a small scale. Etymology The most common explanation for the name is that it derives from the French language, French , meaning 'blue-yellow'. The story goes that Blue John was exported to France where it was used by ''ormolu'' workers during the reign of Louis XVI (1774–92). However, there is no archival record of any Blue John being exported to France, and the early ''ormolu'' ornaments which use Blue John were being manufactured by Matthew Boulton of Birmingham in the 1760s. An alternative origin of the name derives from an old miners' name for the zinc ore sphalerite, which they called "Black Jack". Thus, the unique ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
