Extractions: @import url(/cws/css/screen.css); @import url(/cws/css/themes/phw.css); @import url(/cws/css/datePicker.css); Skip to the content A community website from IOP Publishing physicsworld.com Realmedia.OAS_AD('Top'); Whole site Print edition News In depth Jobs Events Buyer's guide Search Realmedia.OAS_AD('Left'); MAY ISSUE NOW AVAILABLE Members of the Institute of Physics can access a full digital version of Physics World magazine. Simply login here and follow the Physics World link. For maximum exposure, become a Corporate Partner. Contact our sales team Corporate Partners Dec 6, 1999 Even a decade and a half after the discovery of high-temperature superconductivity in ceramic compounds containing copper-oxide planes, these materials continue to puzzle condensed-matter theorists. The challenge is not simply to find a reasonable formula that predicts the uniquely high values for the superconducting transition temperature in the cuprates. Rather, superconductivity is but one aspect of the unique and complex phase diagram exhibited by this class of materials. Depending on the temperature and the level of doping, the cuprates can be insulators, metals or superconductors. The non-superconducting or "normal" phase also exhibits unusual properties (see figure).
Zenergy Power - Zenergy AS is Australia s leading supplier of High Temperature Superconductor products. Efficient devices using an electric wire that transports electricity with http://australiansc.com/
Extractions: Supraleiter sind perfekte verlustfreie Stromleiter. Zenergy Power konzentriert sich mit drei operativen Tochtergesellschaften in Deutschland, Amerika und Australien auf die Kommerzialisierung energieeffizienter Supraleitertechnlogie. Im Mittelpunkt stehen die Bereiche Stromerzeugung und Stromverteilung sowie industrielle Verfahren mit hohem Energieverbrauch.
Quest For A New Class Of Superconductors Fifty years after the Nobelprize winning explanation of how superconductors work, scientists are suggesting another mechanism for the still-mysterious http://www.sciencedaily.com/releases/2007/12/071220133429.htm
Extractions: Share Blog Cite Print Email Bookmark ScienceDaily (Jan. 4, 2008) See also: In a review published December 20 in Nature, researchers David Pines, Philippe Monthoux and Gilbert Lonzarich posit that superconductivity in certain materials can be achieved absent the interaction of electrons with vibrational motion of a material's structure. The review, "Superconductivity without phonons," explores how materials, under certain conditions, can become superconductors in a non-traditional way. Superconductivity is a phenomenon by which materials conduct electricity without resistance, usually at extremely cold temperatures around minus 424 degrees Fahrenheit (minus 253 degrees Celsius)the fantastically frigid point at which hydrogen becomes a liquid. Superconductivity was first discovered in 1911. A newer class of materials that become superconductors at temperatures closer to the temperature of liquid nitrogenminus 321 degrees Fahrenheit (minus 196 degrees Celsius)are known as "high-temperature superconductors." A theory for conventional low-temperature superconductors that was based on an effective attractive interaction between electrons was developed in 1957 by John Bardeen, Leon Cooper and John Schrieffer. The explanation, often called the BCS Theory, earned the trio the Nobel Prize in Physics in 1972.
Extractions: Log in to My.TechnologyReview.com Register Monday, December 17, 2007 A device from Argonne National Lab takes a fresh approach to generating t-rays. By Don Monroe Super-emitter: A mesa built on a superconducting crystal acts as an electromagnetic cavity to promote emission of terahertz radiation (red waves) from the side faces. Credit: A. E. Koshelev, Argonne National Laboratory Researchers have fashioned a high-temperature-superconductor crystal into a structure that generates t-rays, electromagnetic waves with a frequency near one terahertz. Although the superconductor-based technique is not yet ready for commercial use, it offers a new option for exploiting this region of the spectrum for a variety of applications, including airport security and medical monitoring. Because terahertz radiation penetrates many millimeters into tissue, it could enable new medical-imaging techniques. T-rays have also been used in prototype security systems, where they pass readily through fabrics and packaging to reveal concealed weapons and the spectral fingerprints of toxins and explosives.
Magnets & Superconductors Since 1970, the Magnets and superconductors business of ALSTOM Power has been developing and manufacturing a highly specialized range of wires, http://www.power.alstom.com/_looks/alstomV2/frontofficeScripts/index.php?languag
Superconductors - The Naked Scientists 2006.10.05 superconductors are amazing materials whose resistance drops to zero when cooled. Chris looks at how they can be used to detect Pulsars, receive mobile http://www.thenakedscientists.com/HTML/articles/article/superconductors116004828
Extractions: The Birmingham Portfolio Partnership is a £6M research grant from The Engineering and Physical Sciences Research Council (EPSRC). The award, entitled "Superconducting Thin Films - Their Science and Applications", is between the School of Engineering and the School of Physics and Astronomy at The University of Birmingham. The research is at the forefront in Europe and in Engineering centres on the invention, production and application of new superconducting materials and devices. The work in Physics develops and applies techniques for investigating and exploiting the properties of these new materials.
Superconductivity Experiment For example, the ceramics in kits you can buy become superconductors at about 186C. Using liquid nitrogen (LN2) which is at -196C, you can make that http://www.coolmagnetman.com/magsuper.htm
Extractions: Experiments with magnets and conductors Superconductors Superconductivity was first noticed when liquid mercury was cooled to liquid Helium temperatures (4.2K) while its resistivity was being plotted. While approaching that temperature, the resistance was coming down linearly, when all of a sudden it dropped to zero Ohms! Dutch physicist Heike Kamerlingh Onnes was performing this experiment in 1911. Since that time, other elements and combinations of elements have been shown to posses a superconducting state at various temperatures. This table shows the elements which become superconducting and the temperature at which it happens. Most research has been to find materials which are superconducting at higher temperatures. For example, the ceramics in kits you can buy become superconductors at about -186C. Using liquid nitrogen (LN2) which is at -196C, you can make that ceramic superconducting. What is unique about a superconductor? 1. First, its resistance is really zero Ohms, nothing, nada, all gone! This means that if current were flowing in the material, it would produce no heat whatsoever. 2. Second, it will exclude any magnetic fields that come near it, like a magnetic mirror. If a north pole approaches the superconductor, the magnet will behave as though another magnet, just like itself, is approaching from the other side of the surface of the superconductor. At some distance, the magnet's north pole will start to repel the "other magnet's north pole", which is really a reflection of its own. It doesn't matter if it is a north or south pole, it will act the same way. This is the Meissner effect where a magnet will float, or levitate, above a ceramic of superconducting material.
Extractions: Headlines the world over trumpeted the discovery of "high temperature" superconductors (abbreviated HTS), and the media and scientists alike gushed over the marvels that we could soon expect from this promising young technology. Levitating 300-mph trains, ultra-fast computers, and cheaper, cleaner electricity were to be just the beginning of its long and illustrious career. Above : The experimental "maglev" train, currently being tested by Japan's Railway Technical Research Institute , uses "old fashioned" low-temperature superconductors that require liquid helium for a coolant. High-temperature superconductors can use liquid nitrogen instead, which is cheaper, more abundant, and easier to handle. Image courtesy RTRI Today we might ask, like a Hollywood gossip columnist: what ever happened to the "high-temp" hype?
Extractions: To be able to see magnetism directly with your eyes has been a very old dream. In a way magneto-optical imaging is the realization of that dream: you stick your sample under the microscope, put a piece of a magic crystal on top of it, and can through the ocular follow the sample's magnetic behaviour in real-time Links The physical idea behind the magneto-optical imaging is the Faraday effect , i.e., rotation of the light polarization induced by magnetic field. On 13 September, 1845, Michael Faraday wrote in his Diary "...magnetic force and light were proved to have relation to each other. This fact will most likely prove exceedingly fertile and of great value in the investigation of both conditions of natural force" A number of different materials have been applied as indicators in MO imaging: cerous nitrate-glycerol , various europium compounds (EuS, EuSe) [H. Kirchner, Phys. Lett. 26A, 651 (1968)]
Diamagnets And Superconductors Diamagnets and superconductors. Diamagnets and superconductors. There exists a class of materials called diamagnets which exhibit some interesting http://fis.cie.uma.es/old/docencia/2002-03/A109/links/uwinnipeg/mod_tech/node106
Extractions: Diamagnets and superconductors There exists a class of materials called diamagnets which exhibit some interesting properties when an external magnetic field is applied. In these materials, eddy currents consisting of circulating electrons are induced whose magnetic effects are such as to cancel part of the applied external field (typically about 0.1%). A metal detector is a device which relies on this property. In this device, a magnetic field is generated from an electromagnet, which causes eddy currents to be produced. The magnetic fields from the induced currents are in turn picked up by the detector in the form of small currents being produced. Most diamagnetic materials are metals, which have good electrical conductivity properties and so the eddy currents can be relatively easily established. This is the reason these detectors can readily sense metallic objects but not plastics or other poor conductors.
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Extractions: High Temperature Superconductors Our department has an experimental research effort in the area of low-temperature physics, with emphasis on the study of the transport and magnetic behaviors of the high temperature superconductors. The picture at the right [from A. Sleight, Science 1519 (1988)] shows the structure of a typical such material. The high temperature superconductors represent a new class of materials which bear extraordinary superconducting and magnetic properties and great potential for wide-ranging technological applications. The importance of understanding the transport and magnetic behaviors of these novel materials is two-fold. First, it could lead to a better understanding of the basic phenomena of superconductivity in these materials. Second, it could provide ways to improve the magnetic quality of the presently known materials by enhancing flux pinning in a controllable manner. A current-carrying type II When a current is applied to a type II superconductor (blue rectangular box) in the mixed state, the magnetic vortices (blue cylinders) feel a force (Lorentz force) that pushes the vortices at right angles to the current flow. This movement dissipates energy and produces resistance [from D. J. Bishop et al., Scientific American, 48 (Feb. 1993)]. When a type II superconductor is placed in a magnetic field H < H < H , where H and H are the lower and upper critical fields, respectively, the magnetic vortices that penetrate the material should form a uniform triangular lattice (Abrikosov vortex lattice) with a lattice spacing determined by the strength of H. If H is increased, the vortices become more closely spaced and their cores start to overlap. At H
Superconductors An extreme example of a diamagnet is a superconductor. These materials are known primarily through their electrical properties at some relatively low http://theory.uwinnipeg.ca/mod_tech/node107.html
Extractions: Superconductors An extreme example of a diamagnet is a superconductor . These materials are known primarily through their electrical properties - at some relatively low temperature their electrical resistance is exactly zero. Thus, one can establish a current in a superconductor and it will never die away due to resistance, even when the source of potential difference that started the current is removed. Superconductors also have interesting magnetic properties; they are perfect diamagnets: when an applied magnetic field is applied, eddy currents in the superconductor induce a magnetic field which exactly cancels the applied magnetic field. This is the Meissner effect This effect is responsible for the magnetic levitation of a magnet when placed above a superconductor. Suppose, as in Fig. , we place a magnet above a superconductor. The induced magnetic field inside the superconductor is exactly equal and opposite in direction to the applied magnetic field, so that they cancel within the superconductor. What we then have are two magnets equal in strength with poles of the same type facing each other. These poles will repel each other, and the force of repulsion is enough to float the magnet. Such magnetic levitation devices are being tried on train tracks in Japan; if successful, this would make train travel much faster, smoother, and more efficient due to the lack of friction between the tracks and train (in some cases, rather than superconductors, strong electromagnets are used to provide the magnetic levitation).
Superconductors Power Up Already, because of the sophisticated magnets superconductors can produce, superconducting quantum interference devices (dubbed SQUIDs ) are being designed http://www.memagazine.org/backissues/membersonly/january99/features/superpower/s
Extractions: M ore than a decade has passed since the 1986 superconductivity milestone event, which introduced a new set of ceramic compounds that could conduct electricity without energy losses, at much higher temperatures than previously thought possible. c , its critical temperature for superconductivity. Already, because of the sophisticated magnets superconductors can produce, superconducting quantum interference devices (dubbed "SQUIDs") are being designed into nuclear magnetic resonance imaging equipment that has provided awe-inspiring insight into biological tissue make-up. MRI equipment has used superconducting components, like current leads, for years. Because high temperature superconductor (HTS) materials are ultrareceptive to high-frequency signals and cheap enough to cool in a remote box, superconductive communications filters are deployed in the infrastructure that carries wireless phone calls. Now, superconductors are heading, in small steps, into the power grid. Decades of work remain to be accomplished, but the science is ready for engineering development into our daily lives. One high-profile demonstration project has just begun in the United States. Energy Secretary Bill Richardson announced that the Department of Energy has contracted to install the world's first HTS power cable system in an electric utility network.
Extractions: High Temperature Superconductors Since Heike Kamerlingh Onnes discovered superconductivity, people have been creating superconductors with higher critical temperatures. If there were room temperature superconductors we could replace the conductors in our homes and cities with superconductors, thus saving billions of dollars. The Beginning of High Temperature Superconductors High temperature superconductivity began in 1986 when Johannes Georg Bednorz and Karl Alexander Müller in IBM Research Laboratories in Zurich, Switzerland discovered a compound of barium, lanthanum, copper, and oxygen superconductor. The oxide superconductor had a critical temperature of 35K. Müller had decided to study oxide ceramics to see if they could become superconductive. The idea that ceramics could become superconductive was rather strange considering that ceramics are usually not very good conductors of electricity. Müller was interested in a group of ceramics called pervoskites. This group of ceramics were a compound of oxygen and other metals. Many scientist believed that oxides could not be superconductors. The reason he researched oxide ceramics was because the lab he worked in had researched oxides for quite a while, and scientists at the University of Caen in France had found traces that a ceramic compound of copper, oxygen, lanthanum, and barium had electrical conduction.
Extractions: @import "/decorator/css/gridmain.css"; New Scientist Space Technology Environment ... Subscribe to New Scientist ARTICLE Tools Related Articles Web Links Dark energy is so befuddling that it's causing some physicists to do their science backwards. "Usually you propose your theory and then work out an experiment to test it," says Christian Beck of Queen Mary, University of London. A few years ago, however, he and his colleague Michael Mackey of McGill University in Montreal, Canada, proposed a table-top experiment to detect the elusive form of energy, without quite knowing why it might work. Now the pair have come up with the theory behind the experiment. "It is certainly an upside-down way of doing things," Beck admits. Dark energy is the mysterious force that many physicists think is causing the expansion of the universe to accelerate. In 2004, Beck and Mackey claimed that the quantum fluctuations of empty space could be the source of dark energy and suggested a test for this idea. This involved measuring the varying current induced by quantum fluctuations in a device called a Josephson junction a very thin insulator sandwiched between two superconducting layers.
Materials Chemistry - Superconductors superconductors are also perfectly diamagnetic (i.e. they repel a magnetic field); this property was discovered in 1933 and named the Meissner effect. http://materials.binghamton.edu/labs/super/superc.html
Extractions: Figure 1. Electrical resistance of a superconductor. Superconductors are also perfectly diamagnetic (i.e. they repel a magnetic field); this property was discovered in 1933 and named the Meissner effect This compound is often called the 1 2 3 material from the molar ratios of Y:Ba:Cu. The heating-cooling synthesis sequence is shown graphically in figure 2.