20-11-2011, 06:30 PM
if any one of you have a seminar report on ultraconductors plz upload it..i ll be thankfull to you!!!
20-11-2011, 06:30 PM
if any one of you have a seminar report on ultraconductors plz upload it..i ll be thankfull to you!!!
11-12-2012, 12:12 PM
Ultraconductors
ultra conductors.docx (Size: 927.26 KB / Downloads: 193) ABSTRACT Ultraconductors are Room temperature superconductors. They are widely considered for large power applications used by industrial end- users and electric utilities. The prominent application areas include power transmission cables, electric motors, generators, current limiters and transformers. The promising design concepts relay on ultraconductors to a flexible composite conductor, robust enough to handle an industrial environment. Ultraconductors are the electrical conductors which have certain properties similar to present day superconductors. They are best considered as a novel state of matter. They exhibit very high electrical conductivity and current densities over a wide temperature range. INTRODUCTION Superconductivity Superconductivity is the phenomenon in which a material losses all its electrical resistance and allowing electric current to flow without dissipation or loss of energy. The atoms in materials vibrate due to thermal energy contained in the materials: the higher the temperature, the more the atoms vibrate. An ordinary conductor’s electrical resistance is caused by these atomic vibrations, which obstruct the movement of the electrons forming the current. If an ordinary conductor were to be cooled to a temperature of absolute zero, atomic vibrations would cease, electrons would flow without obstruction, and electrical resistance would fall to zero. A temperature of absolute zero cannot be achieved in practice, but some materials exhibit superconducting characteristics at higher temperatures. In 1911, the Dutch physicist Heike Kamerlingh Onnes discovered superconductivity in mercury at a temperature of approximately 4 K (-269o C). Many other superconducting metals and alloys were subsequently discovered but, until 1986, the highest temperature at which superconducting properties were achieved was around 23 K (-250o C) with the niobium-germanium alloy (Nb3Ge) In 1986 George Bednorz and Alex Muller discovered a metal oxide that exhibited superconductivity at the relatively high temperature of 30 K (-243o C). This led to the discovery of ceramic oxides that super conduct at even higher temperatures. In 1988, and oxide of thallium, calcium, barium and copper (Ti2Ca2Ba2Cu3O10) displayed superconductivity at 125 K (-148o C), and, in 1993 a family based on copper oxide and mercury attained superconductivity at 160 K (-113o C). These “high-temperature” superconductors are all the more noteworthy because ceramics are usually extremely good insulators. Technical introduction Ultraconductors are patented1 polymers being developed for commercial applications by Room Temperature Superconductors Inc (ROOTS). The materials exhibit a characteristic set of properties including conductivity and current carrying capacity equivalent to superconductors, but without the need for cryogenic support. The Ultraconductor properties appear in thin (5 - 100 micron) films of certain dielectric polymers following an induced, non-reversible transition at zero field and at ambient temperatures >> 300 K. This transition resembles a formal insulator to conductor (I-C) transition. The base polymers used are certain viscous polar elastomers, obtained by polymerization in the laboratory or as purchased from industrial suppliers. Seven chemically distinct polymers have been demonstrated to date. Properties of Ultraconductors Ultraconductors are the electrical conductors which have certain properties similar to present day superconductors. They are best considered as a novel state of matter. They are made by the sequential processing of amorphous polar dielectric elastomers. They exhibit a set of anomalous magnetic and electric properties including very high electrical conductivity very high electrical conductivity (> 1011 S/cm -1) and current densities (> 5 x 108 A/cm2) over a wide temperature range (1.8 to 700 K). Additional properties established by experimental measurements include: the absence of measurable heat generation under high current; thermal versus electrical conductivity orders of magnitude in violation of the Wiedemann-Franz law; a jump-like transition to a resistive state at a critical current; a nearly zero Seebeck coefficient over the temperature range 87 - 233 K; no measurable resistance when Ultraconductor films are placed between superconducting tin electrodes at cryogenic temperatures. The Ultraconductor properties are measured in discrete macromolecular structures which form over time after the processing. In present thin films (1 - 100 micron) these structures, called 'channels', are typically 1 - 2 microns in diameter, 10 - 1000 microns apart, and are strongly anisotropic in the Z axis. RTS was founded in 1993 to develop the Ultraconductor technology, following 16 years of research by a scientific team at the Polymer Institute, Russian Academy of Sciences, led by Dr. Leonid Grigorov, Ph.D., Dc.S. There have been numerous papers in peer-reviewed literature, 4 contracts from the U.S. government, a landmark patent (US patent # 5,777,292). and a devices patent (US patent # 6,552,883.) Another patent is pending and a fourth now is being completed. To date 7 chemically distinct polymers have been used to create Ultraconductors, including olefin, acrylate, urethane and silicone based plastics. The total list of candidate polymers suited to the process is believed to number in the hundreds. MATERIALS The chemically distinct polymers used to create Ultraconductors to date includeolefin, acrylate, urethane and silicone based plastics. Based on experiment and theory, the total list of candidate polymers suited to the process is believed to number in the hundreds. A successful candidate polymer must be polar without significant crystalline or glass phase at the time of processing. (Intrinsically conducting [conjugated] polymers cannot be used.) Ultraconductor films are prepared on metal, glass, Teflon or semiconductor substrates. The polymer is initially viscose (during processing). For practical application the channels are subsequently “locked” in the polymer, by cross linking, or glass transition. The channel’s characteristics are not affected by either mode. CHARACTERIZATION Characterization of the conducting channels in films was begun in 1983. To date measurements have focused on macroscopic features, specifically, measurements of the magnetic, electric, thermal, chemical, and morphologic nature of the channels. Magnetic Characterization The processing treatment initiates characteristic changes in the magnetic state of the polymer, as measured in a sensitive Faraday magnetic balance. The most typical feature is a growing ferromagnetism which precedes the appearance of electrical conductivity. Additionally, in a small fraction of samples at moderate magnetic fields, extremely high diamagnetism is observed, equivalent to a 5 - 10% volume fraction of a superconducting filler in an insulating polymer. All magnetic readings are established against baseline readings obtained for each sample (before processing) and film substrate. The ferromagnetic response attributable to the changed electronic state of the polymer is therefore quite direct, and is always present in all samples which are conductive. Magnetic field gradients local to the channel structures are also observed by AFM in magnetic mode. Electric Characterization Conductivity The channels were early found to be electrically conductive, for ac and dc currents, at voltages as low as 0.1 mV. In addition, AFM electric field scans (using non-contact mode) indicate pronounced field gradients localized to the conducting channels. The AFM scans also reveal a higher density of points than can be measured by conductive probe, indicating that a proportion of the channel structures do not fully extend substrate to surface. A significant body of experimentation has tested the value of the channel’s conductivity, both under ambient conditions, and over a range of temperatures, pressures, and magnetic field strengths. Test methods include 4- point probe, and superconducting tin electrodes. The measurements indicate that the channels’ conductivity (1011 - 1024 S/cm) is dramatically higher than metals (~ 105 S/cm); and that the high conductivity is insensitive to temperature (from 1.8 K to 700 K) or magnetic fields (to 9 Tesla) . Resistance Electric resistance of the channels has also been measured under various experimental configurations. With 2 point probe technique, newly formed channelstypically have measured resistivities of ~ 1 Ohm. This initial measured resistance can be lowered by several means, including a) application or release of modest local(electrode) pressure; and b) application of pulsed ac currents of increasing amperage over time. Following method b), called ‘training’, channel resistivity is reduced to the range of 25 milliohms. (The disparity between the conductivity of the channels (estimated from a variety of measurements) and the measured resistance is understood to indicate that a significant portion, if not all, of the resistance is at the contact. This conclusion was also supported by 4- point probe measurements, made independently at the Joffe Institute. Thermal Measurements also clearly indicate that the conductivity is not metallic: the thermal conductivity of the conducting channels is found to be equivalent to the surrounding dielectric polymer (indicating that the charge carriers in the conducting channels are poor thermal conductors). The disparity between electric and thermal conductivity of the channels is at least six to seven orders of magnitude beyond metals in this respect. Such a large scale violation of the Wiedmann-Franz law is experimentally known only for Cooper pair electrons, in superconductors. Current Measurements Individual channels (of approximately 1 - 2 microns diameter) also exhibit a maximum current carrying capacity: exceeding a threshold current results in a jump-like rise in resistance, melting of electrode and substrate, and vaporization of a small volume of polymer . While high currents below the threshold do not affect the polymer, a very small step increase (less than 0.1%) above the maximum current results in the characteristic micro explosion event. The threshold current value is increased significantly by the training procedure (application of incrementally stepped increases of pulsed ac currents over time). The micro explosion event was investigated, and several consistent features for the phenomenon were measured. The event typically occurs between currents of 50 to100 amperes; occurs in extremely short (ns) time scales; and corresponds to a sharp, nearly instantaneous rise in resistivity of the channel. The rise in resistance in the channel is measured to occur prior to the rise in temperature which accompanies it, indicating that the event is not thermally triggered. In combination, these factors strongly suggest a ‘critical current’ event, analogous to those known for superconductors. Chemical and Morphologic Characterization When conductive Ultraconductor samples (post processing) are tested and compared against samples of the unprocessed base polymer for contaminants, chemical composition, and metal inclusions, they are found to be identical in all respects to the base material. Examinations of morphologic features of samples, such as transparency, visco elasticity, and so forth, also indicate that the bulk Ultraconductor polymer (excepting the channels) is unchanged from the base polymer. In films, the channel structures are distributed randomly in the polymer, and are of varying lengths to a maximum measured of 100 microns. A proportion present themselves through top and bottom film surfaces, as indicated by direct electric contact. At the free surface, they are typically 1 - 2 microns in diameter, roughly circular, and present as ‘bumps’ approximately 0.6 microns high (see the fig on next page) ATOMIC FORCE MICROSCOPE SCAN These AFM images, produced by Digital Equipment, are of an Ultraconductor polymer film following processing to induce conductivity. The first image (bottom) is a measurement of surface features of a 100 micron square area of film. The probe is in resonant mode above the surface, and two frequency shift measurements are made at each scan point. The brightest regions are raised, about .5 microns (10% of the film thickness). The second image (top) shows the electrostatic field measured at the probe tip, based on an alternating voltage applied to the substrate. Significant field changes (bright areas) are measured at the points imaged in the topographic scan, corresponding to the conducting channels. The distribution of high brightness points in these images coincides with measurements of conducting points made by sampling with an electric probe. The raised topological features also correspond to the present model of channel structure and formation. Charge Separation The polymers used to form Ultraconductors are dielectrics, with no conducting (free) electrons. Ionization is used to produce free electrons in the polymer through an unusual mechanism involving the polymer dipole groups. In dielectric polymers, molecules which are ionized will normally reverse in very short time scales, and the electrons recombine. However, in a polar media the electric dipole groups may prevent this recombination, with the result that charges (such as electrons and ions) become stably separated. This stabilization of separated charges due to electrolytic dissociation in polar solvents is well known. The viscous polar polymer acts in essentially the same manner: the highly mobile molecular dipoles surround and hold the freed electrons in their collective electric fields. These electrons, chemists say, are “solvated”; physicists call them “polarons”. Charge and Lattice Self-organization At this stage, polymer molecular dipoles have solvated (captured) a quantity of electrons freed by ionization (mean concentration ~ 1018 cm-3), and the compensating ions. The dipoles and ions remain attached to the long polymer molecular chains, and are randomly distributed in the polymer. Due to the high mobility of the polymer media, and thermal energy, these randomly distributed charges can move relative to each other. Over time multiple polarons (electrons surrounded by polymer dipoles) are brought closely together, and collide. A theoretic analysis shows that two polarons together form a lower, and preferred, energy state, than solitary polarons: consequently, polarons which collide, join.
07-08-2013, 10:15 AM
plz give ultra conductor seminar report
email: jojinsjjt[at]gmail.com
09-08-2013, 10:06 AM
To get full information or details of ultra conductor please have a look on the pages
https://seminarproject.net/Thread-ultra-...nar-report https://seminarproject.net/Thread-ultra-conductors if you again feel trouble on ultra conductor please reply in that page and ask specific fields in ultra conductor
11-03-2015, 07:51 AM
Plzz any one having ultra conductors ppt plzz upload
11-03-2015, 09:59 AM
To get full information or details of ultra conductors please have a look on the pages
https://seminarproject.net/Thread-ultra-...nar-report if you again feel trouble on ultra conductors please reply in that page and ask specific fields in ultra conductors
02-03-2017, 10:32 PM
i need a pdf on ultrconductors
03-03-2017, 11:57 AM
Ultraconductors ™ are patented materials being developed for commercial applications. They are manufactured by the sequential processing of amorphous polar dielectric elastomers. They exhibit a set of anomalous magnetic and electrical properties, including very high electrical conductivity (> 1011 S / cm -1) and current densities (> 5 x 108 A / cm2) over a wide temperature range (1.8 to 700 K ). Additional properties established by experimental measurements include: the absence of measurable heat generation under high current; Thermal versus orders of magnitude of electrical conductivity in violation of the Wiedemann-Franz law; A transition similar to a jump to a resistive state in a critical current; A Seebek coefficient almost zero in the temperature range 87-233 K; No measurable resistance when Ultraconductor ™ films are placed between tin superconducting electrodes at cryogenic temperatures.
The properties of Ultraconductor ™ are measured in discrete macromolecular structures that are formed over time after processing. In these thin films (1-100 microns), these structures, called "channels", are typically 1-2 microns in diameter, 10-1000 microns apart, and are strongly anisotropic on the Z axis. RTS, Inc was founded In 1993 to develop Ultraconductor ™ technology, after 12 years of research by a scientific team at the Polymer Institute of the Russian Academy of Sciences, led by Dr. Leonid Grigorov, Ph.D., Dc.S. There have been numerous articles in the peer-reviewed literature, 4 contracts of the United States government and a historical patent (US Patent # 5,777,292). To date 7 chemically distinct polymers have been used to create Ultraconductors ™, including olefin, acrylate, urethane and silicone based plastics. The total list of candidate polymers suitable for the process is believed to be in the hundreds. In films, these channels can be observed by various methods, including phase contrast optical microscope, Atomic Force Microscope (AFM), magnetic balance and simple electrical contact. The channel structures can be moved and manipulated in the polymer. Ultraconductor ™ films can be prepared on metal, glass or semiconductor media. The polymer is initially viscous (during processing). For practical application, the channels may be "blocked" in the polymer, by crosslinking or glass transition. Channel features are not affected by any of the modes. A physics model of conducting structures has been developed, which fits well with experimental measurements, as well as a published theory. The next step in material development is to increase the percentage or "concentration" of conductive material. This will lead to films with a greater number of driving points (needed for interposers and other applications) and wire. The yarn is essentially extending a channel to indefinite length, and the technique has been demonstrated in principle. The connection to these conducting structures is made with a metal electrode, and when two channels are connected they are connected. From the engineering point of view, we expect the polymer to replace copper wire and HTS in many applications. It will be considerably lighter than copper, and will have less electrical resistance. |
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