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defect - Definitions from Dictionary.com Defect is the general word for any kind of shortcoming or imperfection, whether literal or figurative: a defect in eyesight, in a plan. Flaw is applied to a defect in quality, caused by imperfect structure (as in a diamond) or brought about during manufacture (as in texture of cloth, in clearness of glass, etc.). Defective was a euphemism for "mentally ill" from 1898 to c.1935. dictionary.reference.com /browse/defect   (584 words)

Crystallographic defect - Wikipedia, the free encyclopedia Dislocations are linear defects around which some of the atoms of the crystal lattice are misaligned. The screw dislocation is more difficult to visualise, but basically comprises a structure in which a helical path is traced around the linear defect (dislocation line) by the atomic planes of atoms in the crystal lattice. Disinclinations are line defects corresponding to "adding" or "subtracting" an angle around a line. en.wikipedia.org /wiki/Crystallographic_defect   (1067 words)

U.S. Patent: 5536948 - Infrared detector element substrate with superlattice layers - July 16, 1996 Since the performance of the infrared detector elements depends substantially upon the density of crystal lattice defects occurring therein, it is desirable to mitigate crystal lattice defect propagation from the substrate to the infrared detector elements. The defect filter of the present invention may additionally be utilized, with appropriate modification, to improve the performance of a wide range of different electro-optical devices whose performance characteristics are affected by the quality of the crystal material from which they are formed. Thus, a defect filter, comprised of two different types of superlattice layers, is disposed intermediate the base 10 and the detector elements 16 so as to mitigate the propagation of defects from the crystalline base layer 10 to the individual infrared detector elements 16, thereby reducing their performance. www.everypatent.com /comp/pat5536948.html   (3579 words)

eMedicine - Dystrophy, Lattice : Article Excerpt by: William Trattler, MD Background: Lattice dystrophy usually is an autosomal dominant condition, and it is the most common of stromal dystrophies. Most corneal dystrophies are dominantly inherited, exceptions are macular dystrophy, type 3 lattice dystrophy, and the autosomal-recessive form of congenital hereditary endothelial dystrophy. Over time, the lattice lines and other opacities coalesce, forming anterior stromal haze that decreases the visual acuity. www.emedicine.com /oph/byname/dystrophy-lattice.htm   (316 words)

defect | | Dictionary & Translation by Babylon Defect can refer to:in biology, the failure of an organism to develop properly (see congenital disorder).in manufacturing, the failure of a product to conform to specification.in materials science, a crystallographic defect is a structural imperfection in a crystal. A closely related concept is error.to abandon allegiance to one's country and go to another.in geometry, the amount by which the sum of the angles at a vertex of a polyhedron falls short of a complete circle. See defect (geometry).a crystallographic defect is a site where a crystal lattice is imperfectly formed.in politics and/or a military context, the verb to defect refers to switching sides (see defector). www.babylon.com /definition/defect/All   (256 words)

Principal Metals A defect appearing in sheets or strips as a segregation or in layers. A surface defect, appearing as a seam, caused by fording over hot metal, fins, or sharp corners and then rolling or forging them into the surface, but not welding them. Lattice lines and lattice planes are lines and planes chosen so as to pass through collinear lattice points, and non-collinear lattice points, respectively. www.principalmetals.com /glossary/ldoc.htm   (519 words)

US Patent No. 6,653,166 - Semiconductor Device The cap layer preferably has a lattice parameter close to that in the underlying substrate, and different from that in the lattice mismatched layer in no strain state. Under these conditions, the cap layer undergoes elastic repulsion from the regions in the vicinity of the dislocations, where the lattice parameter is the most different from that in the substrate. In one embodiment of the invention, the defect-free regions are formed on the substrate with a size preferably tuned in the range of 30-1000 nm, depending on the annealing conditions, thickness of the cap layer, and the lattice mismatch. www.bpmlegal.com /6653166.html   (227 words)

Lecture # 12 It appears that the random walks depend on the lattice geometry, in conflict with eq.(8) which states that in 3-D the mean-square displacement is proportional to n, the number of jumps. When vacancies were finally accepted as a lattice defect, so vacancy-assisted diffusion became accepted, the ring mechanism was discredited. Interchange of a vacancy with a nearest-neighbor atom requires some local distortion of the lattice, and the activation volume is a measure of the local lattice dilation accommodating the exchange between the diffuser and the vacancy. www.rpi.edu /dept/materials/COURSES/DIFFUSION/LECTURE12/lecture12.html   (1214 words)

SimScience - Membranes - Advanced, page 17 In a crystalline surface the constituent molecules are typically arranged in a regular, triangular lattice. Diagram of a triangular lattice with one defect However, notice that there are very many different lattices with one such defect corresponding to the number of possible vertices at which to place the center of the dislocation. simscience.org /membranes/advanced/page17.html   (496 words)

Description of Research--Gary S. Collins There are two types of lattice vacancies and two types of antisite defects (not to mention interstitials.) Analysis of physical properties that depend on defect concentrations using methods that average over defect concentrations have to rely on models of the kinds of defects that are present. The advantage of using PAC to study defects in intermetallics, as opposed to disordered alloys, is that there are fewer distinguishable defect configurations, making resolution potentially better [30]. Dynamical relaxation of a defect associated signal in Pt gave evidence of thermally-activated motion in a complex, perhaps due to motion of the probe atom in a cage of vacancies [34], with an activation energy of 0.34(5) eV. defects.physics.wsu.edu /description.htm   (6384 words)

Process modeling for future technologies The junction depth and activation of the dopant layer both depend on the point defects, which are produced in large concentrations from the implant process itself. Further complicating this behavior is the fact that the vacancy defect is mobile at room temperature, and free vacancies are not found in the crystal. This data clearly shows that the nucleation of defects depends on the implant temperature, since there is a difference of about a factor of 2 in the density. www.research.ibm.com /journal/rd/462/law.html   (3511 words)

[No title] It takes into account the random vacancy jumps in a cubic lattice, appearance and disappearance of vacancies due to climbing of dislocations to be parallel to the initial interface, vacancy quasi-equilibrium in all points of each substance, different frequency of exchange of vacancy and the atoms of different kinds, and external stress gradient. Therefore, the decoration of defects with these atoms is a method to trace defect concentrations and to study the trapping and detrapping mechanism. For characteristic examples the creation of the as-implanted defect structure is analyzed in dependence on the position of the MD box, on the energy and the mass of the ion, and on the target temperature. lucy.mrs.org /meetings/spring98/absbook/AbstractBookZ.html   (16685 words)

Alloy, Metal Terminology (L) Results are determined by analyzing a test ingot sample obtained during the pouring of the steel from a ladle. Lattice lines and lattice planes are lines and planes chosen so as to pass through collinear lattice points, and noncollinear lattice points, respectively. Long vein-like marks appearing on the surface of certain metals, in the direction of the maximum shear stress, when the metal is subjected to deformation beyond the yield point. www.metal-mart.com /Dictionary/dictletl.htm   (322 words)

Semiconductor EPI on recycled silicon wafers - Patent 5131979 After the old defective product structure is removed and the wafer is now stripped "down" to the original substrate lattice, the wafer preferably receives an edge rounding treatment. Fundamental to this invention is the process that redistributes oxygen induced lattice imperfections in the recycled substrate to the interior of the wafer, thus creating a new Denuded Zone and fresh lattice imperfections in the wafer interior for the gettering attraction of unwanted impurities away from the product's electrically active components. At this stage, the polished wafer is not yet ready for its epitaxial layer, because the original wafer's oxygen induced lattice defects are in the near vicinity of the wafer's surface, i.e., the wafer has no Denuded Zone. www.freepatentsonline.com /5131979.html   (3958 words)

Topological Defects Clearly, the lattice to the right is shifted vertically by half a lattice constant: the order parameter has been shifted halfway around the torus. That is, a defect is labeled by two integers (m,n), where m represents the number of extra rows of atoms on the right-hand part of the loop, and n represents the number of extra columns of atoms on the bottom. It represents the fact that we are surrounding the defect with a 2-D spherical surface, rather than the 1-D curve we used in the crystal. www.lassp.cornell.edu /sethna/OrderParameters/TopologicalDefects.html   (2660 words)

Production of substrate for tensilely strained semiconductor - Patent 5759898 Second, the defect density in these thick buffers is still high, about to 10.sup.4 to 10.sup.7 cm-.sup.2 which is too high for realistic VLSI consideration. It is another object of the present invention to provide a pseudo-substrate which includes a layer of a semiconductor having a different lattice constant than silicon which is predominantly relaxed and defect free grown on a layer of silicon. An SOI (silicon on insulator) wafer (or in principle a silicon on sapphire wafer having a layer of silicon on a layer of sapphire) which includes substrate 10, insulating layer 12 and silicon layer 14 is used as the starting material. www.freepatentsonline.com /5759898.html   (2352 words)

US Patent No. 6,653,166 - Semiconductor Device   (Site not responding. Last check: 2007-10-03) The cap layer preferably has a lattice parameter close to that in the underlying substrate, and different from that in the lattice mismatched layer in no strain state. Under these conditions, the cap layer undergoes elastic repulsion from the regions in the vicinity of the dislocations, where the lattice parameter is the most different from that in the substrate. In one embodiment of the invention, the defect-free regions are formed on the substrate with a size preferably tuned in the range of 30-1000 nm, depending on the annealing conditions, thickness of the cap layer, and the lattice mismatch. www.lightlink.com /bbm/6653166.html   (227 words)

Research on Liquid Crystals in the Micro Complex Fluids Laboratory The presence of microscopic defects plays a leading role in determining the flow behavior of complex fluids, especially those that exhibit layered or lamellar structures, such as small molecule liquid crystals, concentrated surfactant solutions, block copolymers, and liquid crystalline polymers. The fluid dynamics of defects impacts every process in which these molecules are used to modify the rheology of a product, improve its stability or mechanical strength, or enhance its transport properties, including processing of materials for optoelectronic devices and displays, templates for information storage media, encapsulation of drugs, and coatings, adhesives, and food products. The goal of our project is to generate well-defined arrays of microscopic defects in layered liquids, and then to use those prepared defect arrays to characterize the fluid dynamics of the defects. www.me.cmu.edu /anna/MCFL/ResLiqCry.htm   (276 words)

EPSL Therefore, with elementary descriptions of ESR center molecular structure and fundemental assumptions of grain deformation during uniaxial compression, it is possible that the results are due to the different lattice arrangements for the OHC and Al centers. The OHC center is formed in the vicinity of lattice dislocations or disparities, when two oxygen atoms that are normally seperated fromone another (by an Si ion) are brough into close proximity to form a weakly bonded OHC center. It is therefore questionable that the extended periods of high temperature needed for thermal diffusion of cations in quartz lattice are generated in fault zones. io.uwinnipeg.ca /~wbuhay/epsl.htm   (1397 words)

Tungsten photonic lattice changes heat to light Now a microscopic tungsten lattice — in effect, a tungsten filament fabricated with an internal crystalline pattern — developed at the Department of Energy’s Sandia National Laboratories has been shown to have potential to transmute the majority of this wasted infrared energy (commonly called heat) into the frequencies of visible light. (Using a tungsten lattice as an emitter at desirable frequencies, model calculations showed that the TPV conversion efficiency reached 51 percent compared with 12.6 percent efficiency with a flbody emitter.) The first step toward this goal, achieved at Sandia by Shawn Lin and Jim Fleming, is reported in the May 2 Nature. Desirable wavelengths not only pass through but also can be changed in direction by creating defects in the artificial crystal that cause the light to follow the defect along like a car passing through a curving tunnel. www.eurekalert.org /pub_releases/2002-05/dnl-tpl043002.php   (794 words)

Green’s function method (for workshop) At the atomistic level, the response of a crystal lattice is given by the lattice Green's function that we calculate using the Born-von Karman model of a crystal lattice. A defect or a discontinuity in the lattice may exert the force that causes lattice distortion. The lattice statics Green's function method is used to calculate the lattice distortion. www.boulder.nist.gov /div853/greenfn/method.html   (570 words)

The Importance of Lattice Defects in Katanin-Mediated Microtubule Severing in Vitro -- Davis et al. 82 (6): 2916 -- ... The simplest model was one in which tubulin dimers were assumed to reside in a defect-free lattice. A break is present if a missing dimer in the first protofilament is connected to a missing dimer one or two rows beneath it (to account for the three-turn helix) in the 13th protofilament. The microtubule lattice is stabilized by interactions of tubulin with its lateral and longitudinal neighbors. www.biophysj.org /cgi/content/full/82/6/2916   (6529 words)

Advanced Lab - Photoelectric Effect:Light Emitting Diodes The additional process is usually the emission of a phonon or a transition to an energy level caused by a lattice defect. These are lattice defects in which the substituting atoms come from the same column of the periodic table as the atoms they replace, so that they do not affect the charge carrier balance in the lattice, unlike the usual donor and acceptor atoms. The advantage of isoelectronic defects lies in the strong localization of the primary bound electron, which is accompanied by a strong increase in the uncertainty of its momentum, in accordance with Heisenberg’s Principle. www.physics.gatech.edu /advancedlab/labs/photoelectric/photoelectric-3.html   (1893 words)

defect a defect in an argument; a defect in a machine. a discontinuity in the lattice of a crystal caused by missing or extra atoms or ions, or by dislocations. He defected from the U.S.S.R to the West. www.infoplease.com /dictionary/defect   (80 words)

SimScience - Membranes - Advanced, page 17 In a crystalline surface the constituent molecules are typically arranged in a regular, triangular lattice. However, notice that there are very many different lattices with one such defect corresponding to the number of possible vertices at which to place the center of the dislocation. As the temperature is increased (and hence the size of random fluctuations) it eventually becomes more likely to see defects even though they are not the lowest energy surfaces. www.simscience.org /membranes/advanced/page17.html   (496 words)

materials science 01 We report strong evidence for the behaviour above 60 K being due to coupling to lattice vibrations; the resulting rate is governed by multiphonon processes. As a consequence, the tunnelling motion involves both defect and lattice modes; when tunnelling from one well to the other, the hydrogen impurity drags its phonon cloud. This may be viewed as a two-state polaron, in analogy to the diffusion of a light particle in a solid. www.ill.fr /AR-97/page/24quant.htm   (762 words)

[No title]   (Site not responding. Last check: 2007-10-03) Perhaps matter is simply a pattern of distortion imposed upon the lattice of space, by the presence of lattice defects. When I viewed my lattice as a group of touching spheres, it became evident that the result of pinching two lattice nodes together was equivalent to one sphere disappearing, while the other moved midway between the two previously undisturbed lattice locations. I was perplexed about which defect structures to associate with the other three members of the lepton family, the muon, and the electron and muon neutrinos (the tau had not been postulated at that time). www.infiniteparticlephysics.com /howitbegan.htm   (3193 words)

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