In mineralogy and crystallography , crystalstructure is a unique arrangement of atom s or molecule s in a crystal ... 1 ref A crystalstructure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice ... . ref name Solid State Physics 2010 A crystal s structure and symmetry play a role in determining many of its physical properties, such as cleavage crystal cleavage , electronic band structure , and crystal ... cell The crystalstructure of a material or the arrangement of atoms within a given type of crystal ... space describe the bulk arrangement of atoms of the crystal. The crystalstructure has a three ... rise to the following series center ... ABABABAB .... center This type of crystalstructure is known ..., then the following sequence arises center ... ABCABCABC ... center This type of crystalstructure .... The Bravais lattices are sometimes referred to as space lattices . The crystalstructure consists ... at least one point unmoved and that leave the appearance of the crystalstructure unchanged. These symmetry ... crystal systems. Space groups The space group of the crystalstructure is composed of the translational ... Petch relationship. Since grain boundaries are defects in the crystalstructure they tend to decrease ... for one of the principal atomic components within the crystalstructure, alteration in the electrical ... lattice allow Shear stress shear at lower stress than that needed for a perfect crystalstructure ... Crystalstructure prediction File Sodium chloride 3D ionic.png thumb Crystalstructure of sodium chloride ... ref After postulating a direct correlation between electron concentration and crystalstructure in beta ... structures respectively. The relationship between d electrons and crystalstructure thus becomes apparent .... Below 13.2 C, tin exists in the gray form, which has a diamond cubic crystalstructure ... is polar is determined solely by its crystalstructure. Only 10 of the 32 point groups ... to as the pyroelectric classes. There are a few crystal structures, notably the Perovskite structure ... more details
For the mineral, see Wurtzite unreferenced date January 2012 Image Wurtzite kassebaum.gif thumb right 150px Wurtzite structure Image Wurtzite unit cell 3D balls.png thumb right 150px Wurtzite unit cell Image Wurtzite polyhedra.png thumb 150px right Wurtzite structure image Hexagonal lattice.svg thumb 150px right General hexagonal crystal structure The wurtzite crystal structure , named after the mineral wurtzite , is a crystal structure for various binary compound s. It is an example of a hexagonal crystal system . Among the compounds that can take the wurtzite structure are wurtzite itself, Silver iodide AgI , Zinc oxide ZnO , Cadmium sulfide CdS , Cadmium selenide CdSe , Silicon carbide SiC , Gallium III nitride GaN , Aluminium nitride AlN , and other semiconductors. In most of these compounds, wurtzite is not the favored form of the bulk crystal, but the structure can be favored in some nanocrystal forms of the material. In materials with more than one crystal structure, the prefix w is sometimes added to the empirical formula to denote the wurtzite crystal structure, as in w BN . Each of the two individual atom types forms a sublattice which is close packing HCP type short for hexagonal close pack . When viewed altogether, the atomic positions are the same as in lonsdaleite hexagonal diamond . Each atom is tetrahedrally coordinated. The wurtzite structure is centrosymmetry non centrosymmetric i.e., lacks inversion symmetry . Due to this, wurtzite crystals can and generally do have properties such as piezoelectricity and pyroelectricity , which centrosymmetric crystals lack. fact date January 2012 External links http cst www.nrl.navy.mil lattice struk b4.html The Wurtzite structure Category Crystallography fa ... more details
ICSD is a database of inorganic crystalstructure data. It was founded in 1978 by G nter Bergerhoff University of Bonn and I.D.Brown University of McMaster, Canada . It is now produced by the Fachinformationszentrum Karlsruhe in Europe and the U.S. National Institute of Standards and Technology . It seeks to contain information on all inorganic crystal structures published since 1913, including pure chemical element element s, mineral s, metal s, and intermetallic compounds with atomic coordinates . ICSD contains 103,679 entries As of 2008 alt as of mid 2008 and is updated twice a year. A Microsoft Windows Windows based Personal Computer PC version has been developed in co operation with the National Institute of Standards and Technology NIST , and a PHP MySQL web based version in co operation with the Institut Laue Langevin ILL Grenoble. See also Crystallographic database External links http www.fiz karlsruhe.de icsd.html Information and a demonstration version Category Inorganic chemistry Category Chemical databases Category Crystallographic databases chem stub fr Inorganic crystalstructure database ... more details
Crystalstructure prediction CSP is the calculation of the crystalstructure s of solids from first principles. Reliable methods of predicting the crystalstructure of a compound, based only on its molecular structure, has been a goal of the physical sciences since the 1950s. ref name cryptic cite journal ... Nature Materials volume 7 pages 937 946 year 2008 doi 10.1038 nmat2321 title Crystalstructure ... different things. Most commonly, by crystalstructure prediction one understands search for minimum ... journal Nature Materials volume 5 year 2006 pages 623 626 title Crystalstructure transformations ... Physics volume 124 pmid 244704 issue 10 pages 8 13 year 2006 title Crystalstructure prediction ... of each short listed candidate structure. ref name Neumann cite journal journal Angewandte Chemie International Edition volume 47 issue 13 pages 2427 2430 year 2008 title A Major Advance in CrystalStructure Prediction author M. A. Neumann, F. J. J. Leusen, J. Kendrick doi 10.1002 anie.200704247 pmid 18288660 ref Crystalstructure prediction software http mysbfiles.stonybrook.edu aoganov .... Further reading cite book title Modern Methods of CrystalStructure Prediction editor A. R. Oganov ......7..937W ref History COI date March 2011 The crystal structures of simple ionic solids have ... the structure of complex ionic crystals journal Journal of the American Chemical Society volume ... 53 year 2003 title Predicting crystal structures The Parrinello Rahman method revisited author Martonak ... which often works . Molecular crystals The crystal structures of molecular substances, particularly ... little directionality. ref name cryptic Predicting organic crystal structures is important to academic ... title Model predicts structure of crystals author K. Sanderson pmid 18063962 volume 450 bibcode ... the crystal structures of small organic molecules a report on the fourth blind test author ... possible crystal structures using a customised molecular mechanics MM force field, and finishes by using ... more details
Greenwood indium In Tetragonal crystal system tetragonal slightly distorted fcc structure ref name ... at 234 K and 1 atm it is liquid at room temperature and thus has no crystalstructure at ambient conditions this structure can be considered to be a distorted hcp lattice with the nearest neghbours ... with increasing atomic number. See also Crystalstructure in general the s block elements ... and the structure refers to the low temperature form. The melting points of the metals in Kelvin K is shown above the element symbol. Most of metallic elements are variations of the cubic crystal system ... style border 1px solid aaaaaa width 100pt background color silver unusual structure style border ... Lr br center Unusual structures class wikitable Element crystal system coordination number ... Greenwood zinc Zn Hexagonal crystal system hexagonal distorted from ideal hcp. 6 nearest neighbors in same plane 6 in adjacent planes 14 further away ref name Greenwood gallium Ga Orthorhombic crystal ..., 2 at 279 pm. ref name Greenwood The structure is related to Iodine. cadmium Cd hexagonal distorted ... white tin form thermodynamical stable above 286.4 K antimony Sb Rhombohedral crystal system rhombohedral ... pm. ref name Greenwood Bi, Sb and grey As have the same space group in their crystal polonium Po ... U orthorhombic strongly distorted hcp structure. Each atom has four near neighbours, 2 at 275.4 pm, 2 ... Conference, Vail, Colorado, Feb. 1974 ref neptunium Np orthorhombic highly distorted bcc structure ... lattice struk a c.html ref plutonium Pu Monoclinic crystal system monoclinic slightly distorted hexagonal structure. 16 atoms per unit cell. Lattice parameters a 618.3 pm, b 482.2 pm, c 1096.3 pm ... ref Usual crystal structures Close packed metal structures Many metals adopt close packed structures ... struk c19.html ref Hexagonal close packed In the ideal hcp structure the unit cell axial ratio ... where the unit cell is distorted in one direction but the structure still retains the hcp space group ... more details
with boron . Their crystalstructure and chemical bonding depend strongly on the metal element M and on its ... the latter originates from their complex, amorphous like , crystalstructure. Metal borides ... in a Hexagonal crystal system hexagonal AlB sub 2 sub type layered structure. Hexaborides ... the YAlB sub 14 sub crystalstructure using a single crystal grown by the high temperature solution ... nm, and the atomic coordinates and site occupancies are summarized in Crystalstructure of boron rich .... Vacancies at the Y and Al sites are ignored. ref name korsukova2 Figure 3 shows the crystalstructure ... in Crystalstructure of boron rich metal borides data page Table I table I . If both metal elements ... They reported that YB sub 66 sub has a Cubic crystal system face centered cubic structure with space ... Atomic coordinates and site occupancies are summarized in Crystalstructure of boron rich metal borides ... and single crystalstructure analysis. ref name higashiyb50 The structure analysis indicated ... crystalstructure space group Pbam , No. 55 with lattice constants of a 1.674 1 nm, b 1.7667 1 nm ... coordinates and site occupancies are summarized in Crystalstructure of boron rich metal borides data ..., i.e. have a similar crystalstructure, to boron carbide B sub 4 sub C . The latter has a structure ... compounds. ref name jasper1 Single crystalstructure analysis yielded trigonal symmetry for ScB sub ... atomic coordinates are summarized in Crystalstructure of boron rich metal borides data page Table IVa ... The crystalstructure, solved for a representative compound YB sub 22 sub C sub 2 sub N, belongs ... 2 sub N are summarized in Crystalstructure of boron rich metal borides data page Table IVb table IVb . Y, Ho, Er, Tm and Lu also form REB sub 28.5 sub C sub 4 sub which has a trigonal crystalstructure ... formula units in the unit cell. Structure data of YB sub 28.5 sub C sub 4 sub are summarized in Crystal ... sub C sub 0.33 sub Si sub 3.0 sub File Borfig14.png thumb 240px Fig. 14 . Crystalstructure of RE sub ... more details
TOC right This page contains crystalstructure data used in the article crystalstructure of boron rich metal borides . Table I class wikitable Structure data for YAlB sub 14 sub ref name korsukova Atom Site x y z Occ. b sub iso sub sup 2 sup Y 8 i 0.02511 8 1 4 0.64217 3 0.310 1 Anisotropic Al 4 c ... K, Ishizawa Y and Takami M year 1997 title CrystalStructure of YB41Si1.2 journal J. Solid State ... V V, Braudt N B, Gippius A A and Nyan K K year 1989 title CrystalStructure, Electrical, and Magnetic ... stabilized polyborides REB15.5CN RE Sc, Y, Ho, Er, Tm, Lu , crystalstructure and compound formation ... Crystalstructure of new rare earth boron rich solids REB28.5C4 journal J. Alloys Compd. doi 10.1016 ... II class wikitable Structure data for YB sub 62 sub ref name tanakayb66 Atom Site x y z Occ. U sub ... 11 0.25 0.25 0.110 12 0.0414 43 Table III class wikitable Structure data for YB sub 41 sub Si sub ... 2 sup sub 11 sub b sup 2 sup sub 22 sub c sup 2 sup sub 33 sub . Table IVa Structure data for homologous compounds. class wikitable a . Structure data of ScB sub 15.5 sub CN ref name jasper1 Atom ... values was fixed at 1.0. Table IVb class wikitable b . Structure data of YB sub 22 sub C sub 2 sub ... 0.99 6 3.19 0 N 6 c 0 0 0.401 3 0.84 0 0.95 8 Table IVc class wikitable c . Structure data of YB sub ... Structure data for Y sub x sub B sub 12 sub C sub 0.33 sub Si sub 3.0 sub x 0.68 ref name tanakaREBSi3 ... 3 Si3 C3 0.413 C3 Si3 1.786 24 Si3 Si3 1.373 10 Table VI class wikitable Structure data for ScB sub ... by structure analysis. Table VII class wikitable Structure data for ScB sub 17 sub C sub 0.25 sub ... 24 0.0 0.53 45 8 B18 6 m 0.0379 10 0.0758 10 1 2 0.67 44 6 Table VIII class wikitable Structure .... Table IX class wikitable Structure data for Sc sub 4.5 x sub B sub 57 y z sub C sub 3.5 ... wikitable Structure data for Sc sub 3.67 x sub B sub 41.4 y z sub C sub 0.67 z sub Si sub 0.33 ... T, Sato A and Zhang F X year 2009 journal J. Phys. Conf. Ser. title Structure refinement of quaternary ... more details
wiktionarypar CrystalcrystalCrystal is a form of matter significant in chemistry and mineralogy. Crystal may also refer to TOCright Places Crystal, Indiana Crystal, Maine Crystal, Minnesota Crystal City, Missouri Crystal, Nevada disambiguation Crystal, New Mexico Crystal, North Dakota Crystal Township, Hancock County, Iowa Crystal Township, Tama County, Iowa Crystal Township, Montcalm County, Michigan Crystal Township, Oceana County, Michigan Media and entertainment Crystal book Crystal book , a book by Walter Dean Myers Crystal comics , a Marvel comic book superheroine Crystal , a poem by Patti Smith in the Seventh Heaven book Seventh Heaven collection Crystal , a song by Fleetwood Mac from their 1975 Fleetwood Mac 1975 album Fleetwood Mac album Crystal song Crystal song , by New Order Crystal album , an album by Crystal Gayle Pok mon Crystal , a video game Science and technology CrystalCrystal base Crystal Clear software development , a member of the Crystal family of methodologies Crystal growth , a major stage of a crystallization process Crystal lattice CrystalstructureCrystal oscillator , a device that creates an electrical signal, often used in timekeeping Crystal radio , a type of radio receiver Crystal Reports , a software program used to design and generate reports from databases Crystal software , a software program used in quantum chemistry Crystalline cohomology ... disambiguation Liquid crystal , a substance in a phase of matter between a conventional liquid and a solid crystal Photonic crystal , an arrangement of optical materials Phononic crystal , an arrangement of elastic materials Seed crystal Single crystal Other synonyms Digital Research s Graphical Environment Manager GEM , originally code named Crystal . Companies and brands Crystal Cruises , a cruise ship line Crystal Dynamics , an American video game developer Crystal Hot Sauce , a brand of hot sauce Other uses Crystal steamboat Crystal steamboat Crystal ball , an object used ... more details
wiktionary structure The structure of a thing is how the parts of it relate to each other, how it is assembled . Structure may also refer to Architectural structure , a man made structure used or intended for supporting or sheltering any use or continuous occupancy Building , Non building structure & Building disambiguation Canopy ecology structure, organization or three dimensional geometry of a plant canopy Community ecology structure, ecological organization of a biological community Chemical structure , the spatial arrangement of atoms and bonds in a molecule Protein structureCrystalstructure , structure of liquids and glasses , the spatial arrangement of ions, atoms, or molecules in condensed matter Data structure , a way of storing data in a computer so that it can be used efficiently Mathematical structure on a set, additional mathematical objects that in some manner attach to the set, making it easier to visualize or work with, or endowing the collection with meaning or significance Structure mathematical logic Algebraic structure Social structure , a pattern of relations Structure and agency , two confronted theories about human behaviour Structural geology , the three dimensional distribution of rock bodies and their planar or folded surfaces, and their internal fabrics Deep structure logical language structure in linguistics The Structure of Scientific Revolutions , a book by Thomas Kuhn on the history of science Structure journal , a scientific journal describing protein structure s Large scale structure of the cosmos Capital structure Financial structure , a cocept within structured finance Structure, the former name for the Express Men clothing brand Structures Structures Boulez , composition Structures album , by John Digweed Structures from Silence , album by Steve Roach Structures of Death , album by Fleshcrawl See also Struct disambiguation disambig ar br Framm da Struktur flertydig fr Structure gl Estrutura it Struttura hu Strukt ra egy rtelm s t ... more details
A chemical structure includes molecular geometry , electronic structure and crystalstructure of molecule s. Molecular geometry refers to the spatial arrangement of atom s in a molecule and the chemical bond s that hold the atoms together. Molecular geometry can range from the very simple, such as diatomic oxygen or nitrogen molecules, to the very complex, such as protein or DNA molecules. Molecular geometry can be roughly represented using a structural formula . Electronic structure describes the occupation of a molecule s molecular orbital s. The theory of chemical structure was first developed by Aleksandr Butlerov , which stated that the chemical compounds are not a random cluster of atoms and functional groups but structures with definite order formed according the valency chemistry valency of the composing atoms . Structure determination Structural determination in chemistry is the process of determining the chemical structure of molecules. Practically, the end result of such process is the obtainment of the coordinates of the atoms in a molecule. ref name lecture07uwec http www.chem.uwec.edu Chem406 F06 Pages lecture notes lect07 C406 lect07 notes.pdf C406 lect07 Bot generated title PDF, 936 KiB ref The methods by which one can determine the structure of a molecule include spectroscopy , such as nuclear magnetic resonance NMR , infrared spectroscopy and Raman spectroscopy , electron microscopy , and x ray crystallography x ray diffraction . The last technique can produce three dimensional models at atomic scale optical resolution resolution , as long as crystal s are available ... the chemical structure Structural elucidation X ray diffraction Proton NMR Carbon 13 NMR Mass spectrometry Infrared spectroscopy The following are common methods for determining the electronic structure ... of drugs QSAR , quantitative structure affinity relationship Chemical property Molecular property ... es Estructura qu mica fr Structure chimique he nl Chemische structuur ja nds Cheemsch ... more details
refimprove date March 2010 orphan date March 2010 A crystal depending upon its chemical composition , bonding power, atmospheric pressure and ambient environment form clusters. A crystal cluster is the development of a crystal system and is also known as a crystal family . Though crystal family as a technical term in crystallography is a matrix of probabilities determining the range of possible crystal formation and lattice structure. Crystal cluster is a non technical term and generally used in the community. Image Quartz, Tibet.jpg thumb right 300px A quartz cluster, crystalline silica , sourced from Tibet . See also Crystalstructure Crystallization References Reflist 2 Further reading Mechanical and Physical Properties of Whiskers , CRC Handbook of Chemistry and Physics, 55th edition. DEFAULTSORT Crystal Growth Category Condensed matter physics Category Crystallography Category Crystals Category Materials science Category Mineralogy ... more details
is the undistorted cubic crystal system cubic structure the symmetry is lowered to orthorhombic , tetragonal or trigonal in many perovskites. ref cite journal title Energetics and Crystal Chemical ...Image Perovskite.jpg thumb Structure of a perovskite with a chemical formula ABX sub 3 sub . The red spheres are X atoms usually oxygens , the blue spheres are B atoms a smaller metal cation, such as Ti ... Chem. Mater. year 1998 volume 10 issue 10 page 2787 doi 10.1021 cm9801901 ref A perovskite structure is any material with the same type of crystalstructure as calcium titanium oxide CaTiO sub 3 sub , known as the perovskite structure , or sup XII sup A sup 2 sup sup VI sup B sup 4 sup X sup 2 sup sub 3 sub with the oxygen in the cubic crystal system face centers . ref name Min cite book title ... atoms. The ideal cubic symmetry structure has the B cation in 6 fold coordination, surrounded by an octahedron ... ion size requirements for stability of the cubic structure are quite stringent, so slight ... numbers of A cations, B cations or both are reduced. Natural compounds with this structure are perovskite , loparite , and silicate perovskite. ref name Min Structure The perovskite structure is adopted ... . The relative ion size requirements for stability of the cubic structure are quite stringent, so ... increases, the O sup 2 sup ions compress so olivine transforms to the spinel structure, which at still higher pressure converts to a perovskite structure and a coexisting periclase structure. ref name ... has the orthorhombically distorted perovskite structure GdFeO sub 3 sub type structure that is stable ... External links http cst www.nrl.navy.mil lattice struk e2 1.html Cubic Perovskite Structure , including a http cst www.nrl.navy.mil lattice struk.jmol e2 1.html Java applet where the structure can be interactively ... Perovskite Structure Category Mineralogy Category Natural materials ca Perovskita cs Perovskit de Perowskit es Perovskita fa fr P rovskite structure it Perovskite nl Perovskiet ja ... more details
Unreferenced date July 2008 Crystal chemistry is the study of the principles of chemistry behind crystals and their use in describing structure property relations in solids. The principles that govern the assembly of crystal and glass structures are described, models of many of the technologically important crystal structures Zinc Blende , Alumina , Quartz , Perovskite are studied, and the effect of crystalstructure on the various fundamental mechanisms responsible for many physical properties are discussed. The objectives of the field include identifying important raw materials and minerals as well as their names and chemical formulae. describing the crystalstructure of important materials and determining their atomic models. learning the systematics of crystal and glass chemistry. understanding how physical and chemical properties are related to crystalstructure and microstructure. studying the engineering significance of these ideas and how they relate to industrial products past, present, and future. Topics studied are Chemical bond ing, Electronegativity Fundamentals of crystallography crystal systems, Miller Indices , symmetry elements, bond lengths and radii, theoretical density Crystal and glass structure prediction Pauling s rules Pauling s and Zachariasen s rules Phase diagrams and crystal chemistry including solid solution s Imperfections including defect chemistry and Crystallographic defect line defects Phase transitions Structure property relations Neumann s law Neumann s law , melting point, mechanical properties hardness, slip, Cleavage crystal cleavage , elastic moduli , wetting , thermal properties thermal expansion, specific heat , thermal conductivity , diffusion, ionic conductivity , refractive index , absorption electromagnetic radiation absorption , color, Dielectrics and Ferroelectricity Ferroelectrics , and Magnetism Crystal structures of representative metals , semiconductors , polymers , and ceramics Category Chemistry Category Crystallography ... more details
Structure The Diamond cubic crystalstructure occurs in diamond carbon , most semiconductors and tin ...In condensed matter physics and crystallography , the static structure factor or structure factor for short is a mathematical description of how a material scatters incident radiation. The structure factor .... The static structure factor is measured without resolving the energy of scattered photons electrons neutrons. Energy resolved measurements yield the dynamic structure factor . Derivation Let us ... 2 rangle N left f mathbf q right 2 S mathbf q math , EquationRef 3 thus defining the structure factor ... rangle math . EquationRef 4 Perfect crystals In a crystal , the constitutive particles are arranged periodically, forming a crystal lattice lattice . In the following, we will consider that all particles are identical so the above separation in factor and structure factors EquationNote 3 holds . We ... and completely regular, the system is a perfect crystal . In addition, we will neglect all thermal ... write math S mathbf q frac 1 N left sum j 1 N mathrm e i mathbf q mathbf R j right 2 math . The structure ... thumb Structure factor of a periodic chain, for different particle numbers math N math . The reciprocal ... is odd . The sum of the phase factors is a simple geometric series and the structure factor becomes ... fulfills Bragg s law . Three dimensions Lattice with a basis To compute structure factors for a specific ... in terms of their Miller index Miller indices , it is useful to examine a specific structure ... crystal, all the form factors math f math are the same. The intensity of a diffracted beam scattered with a vector math mathbf K 2 pi a h hat x k hat y l hat z math by a crystal plane ... at the following result for the structure factor for scattering from a plane math hkl math ... us that for a reflection to appear in a diffraction experiment involving a body centered crystal, the sum ... diffraction peak from a material with a BCC structure is typically the 110 . The 110 plane is the most ... more details
by automated software ref Cite journal author Spek AL year 2003 title Single crystalstructure ... S0021889802022112 ref as a requirement for small molecule crystalstructure papers submitted to the International ... macromolecular crystal structures Relationship to Resolution and B factor Data Validation Structure ...Image Structure validation concept.jpg thumb right Structure validation concept model of a protein each ball is an atom , and magnified region with electron density data and 3 bright flags for problems Macromolecular structure validation is the process of evaluating reliability for 3 dimensional atomic models of large biological molecules such as proteins and nucleic acids . These models, which provide ... from the atomic model. For a well determined small molecule structure the R factor is nearly as small ... Structural Database a quarter of a million crystal structures and rising journal Acta Crystallographica ... 1992 title Free R value a novel statistical quantity for assessing the accuracy of crystal structures ... parameters for X ray protein structure refinement journal Acta Crystallographica volume A 47 pages ... GJ year 2000 title Validation of protein crystal structures journal Acta Crystallogr volume D 56 pages ... Data Bank journal Structure volume 19 pages 1395 1412 PMID 22000512 doi 10.1016 j.str.2011.08.006 ... evaluation criteria apply globally to an entire experimental structure, most notably the Resolution ... residues or local regions in the 3D structure, such as fit to the local electron density map or steric ... an accurate picture of the reliability of the structure model or any hypothesis based on local features ... further restraints applied to a structure model during refinement. Model Validation As Above ... PSVS Protein Structure Validation Server at the NESG http code.google.com p cing CING Common Interface for NMR structure Generation software http http www.ebi.ac.uk thornton srv software PROCHECK ProCheckNMR ... structure ... more details
Unreferenced date December 2009 Orphan date December 2009 An anisodesmic crystal sometimes anisodemic crystal is a crystal containing chemical bond bonds with differing electrostatic valencies. All other crystals are known as isodesmic crystal s or isodemic and examples include diamond and halite . These terms are of particular importance when discussing the structural chemistry of mineral s. The electrostatic valency is a measure of the strength of bonds, being the valence charge divided by the coordination number . Linus Pauling s second rule of ionic bonding, the Electrostatic Valence Principle states, An ionic structure will be stable to the extent that the sum of the strengths of the electrostatic bonds that reach an anion equals the charge on that anion. When there is more than one type of bonding in a crystal, strongly anisotropic physical properties can result such as those of graphite . Many other substances have anisotropic physical properties. Such properties are directly related to the atomic structures of the substances. Conversely, halite is an example of an isotropic crystal with equal hardness in all directions. DEFAULTSORT Anisodesmic Crystal Category Crystals ... more details
In solid state physics and crystallography , when describing crystalstructure , a supercell is a repeating unit cell of the crystal that contains several primitive cell s. In some cases, these primitive cells of the underlying crystal are perturbed so that the supercell becomes the new primitive cell. For example, in body centered bcc or face centered fcc cubic crystal system cubic crystals , the primitive cell is a parallelepiped or rhombohedron , respectively, but the conventional unit cell used to describe these structures is a simple cubic supercell. Supercells are also commonly used in computational models of crystal defect s, in order to allow the use of periodic boundary condition s. See also Empty section date July 2010 References reflist Unreferenced date April 2008 External links Category Condensed matter physics Category Crystallography geometry stub it Supercella cristallografia ... more details
A complex structure may refer to Almost complex manifold Complex manifold Linear complex structure Complex data structure See also Real structure disambig ... more details
crystallization Unreferenced date December 2009 A seed crystal is a small piece of single crystal polycrystal material from which a large crystal of the same material typically is to be grown. The large crystal can be Crystal growth grown by dipping the seed into a supersaturated solution , into molten material that is then cooled, or by growth on the seed face by passing vapor of the material to be grown over it. The theory behind this effect is thought to derive from the physical intermolecular interaction that occurs between compounds in a supersaturated solution or possibly vapor . In solution, liberated soluble molecules solution solute are free to move about in random flow. This random flow permits for the possibility of two or more molecular compounds to interact. This interaction can potentiate intermolecular forces between the separate molecules and form a basis for a crystal lattice . The placement of a seed crystal into solution allows the Recrystallization chemistry recrystallization process to expedite by eliminating the need for random molecular collision interaction. By introducing an already pre formed basis of the target crystal to act upon, the intermolecular interactions are formed much more easily readily than relying on random flow. Often, this phase transition from solute in a solution to a crystal lattice will be referred to as nucleation . Seeding is therefore said to decrease the necessary amount of time needed for nucleation to occur in a recrystallization process. One example where a seed crystal is used to grow large boule crystal boules or ingot s of a single crystal is the semiconductor industry where methods such as the Czochralski process or Bridgman technique are employed. See also Crystalstructure Crystallization Laser Heated Pedestal Growth Micro Pulling Down Single crystal Wafer electronics Category Crystals de Impfkristall fa nl Entkristal sv Ympning teknik DEFAULTSORT Seed Crystal ... more details
Crystal Springs may refer to Crystal Springs, Saskatchewan Crystal Springs, Arkansas Crystal Springs, California Crystal Springs, California, former name of Sanitarium, California Crystal Springs, Florida Crystal Springs, Mississippi Crystal Springs, Nevada Crystal Springs Dam Crystal Springs Reservoir See also lookfrom Crystal Springs geodis ca Crystal Springs de Crystal Springs es Crystal Springs it Crystal Springs nl Crystal Springs pl Crystal Springs sv Crystal Springs vo Crystal Springs ... more details
Crystal Lakes is the name of two places in the United States Crystal Lakes, Missouri Crystal Lakes, Ohio geodis ca Crystal Lakes de Crystal Lakes it Crystal Lakes nl Crystal Lakes pl Crystal Lakes vo Crystal Lakes ... more details
Cell structure may refer to An organelle , or the layout of organelles of the biological cell itself The structure of a covert cell , often involved in underground resistance, organised crime, terrorism or any group requiring stealth in its operations In mathematics, the structure of a cell complex disambig ... more details
unreferenced date June 2009 bot yes An abstract structure in mathematics is a formal object that is defined by a set of laws, properties, and relationships in a way that is logically if not always historically independent of the structure of contingent experiences, for example, those involving physical objects. Abstract structures are studied not only in logic and mathematics but in the fields that apply them, as computer science , and in the studies that reflect on them, as philosophy and especially the philosophy of mathematics . Indeed, modern mathematics has been defined in a very general sense as the study of abstract structures by the Nicolas Bourbaki Bourbaki group see discussion there, at algebraic structure and also structure category theory structure . An abstract structure may be represented perhaps with some degree of approximation by one or more physical objects this is called an implementation or instantiation of the abstract structure. But the abstract structure itself is defined in a way that is not dependent on the properties of any particular implementation. An abstract structure has a richer structure than a concept or an idea . An abstract structure must include precise rules of behaviour which can be used to determine whether a candidate implementation actually matches the abstract structure in question. Thus we may debate how well a particular government fits ... is or is not a valid game of chess. Examples A sorting algorithm is an abstract structure, but a recipe ... is an abstract structure, but an orchestration is not, because it depends on the properties of particular instruments. Euclidean geometry is an abstract structure, but the theory of continental drift is not, because it depends on the geology of the Earth . A formal language is an abstract structure ... Formal science s Mathematical structure math stub Category Abstraction Category Mathematical terminology Category Structure da Abstrakt begreb lt Abstrakti strukt ra th tr Soyut yap ... more details
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