Physics
Superconductivity
Superconductivity is a phenomenon in which certain materials can conduct electricity with zero resistance when cooled below a critical temperature. This allows for the efficient transmission of electricity and the creation of powerful electromagnets. Superconductors also exhibit the Meissner effect, where they expel magnetic fields, making them useful for applications such as magnetic levitation and MRI machines.
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11 Key excerpts on "Superconductivity"
eBook - PDF- Tao Xiang, Congjun Wu(Authors)
- 2022(Publication Date)
- Cambridge University Press(Publisher)
1 Introduction to Superconductivity 1.1 Basic Properties of Superconductivity Superconductivity, as an emergent macroscopic quantum phenomenon, is one of the most important subjects of contemporary condensed matter physics. It was first discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911 [8–10]. In 1908, Onnes and his assistants successfully liquefied helium and for the first time reached low temperatures below 4.25K. This was a historic breakthrough for low temperature physics. When they applied this technique and measured the resistance of mercury, they found that its resistance dropped abruptly from 0.1 to below 10 −6 within a narrow temperature range of 0.01 K around 4.2 K. This important discovery opened up the field of Superconductivity and related applications. It also greatly stimulated the study of quantum emergent phenomena in condensed matter physics. Understanding the phenomena and exploring the mechanism of superconductiv- ity are historically important in the development of condensed matter physics. In the early days, condensed matter physics was not considered as fundamental as quantum field theory by the mainstream of physics. Various classical and quan- tum mechanical theories were developed to study solid state phenomena, such as the Drude theory of transport, the Sommerfeld theory of electrons, the Debye the- ory of phonons, and the Bloch theory of energy band structures. However, there were few original fundamental principles arising from this field. This situation was changed when the mechanism of Superconductivity as well as that of superfluidity was revealed. A superconductor has two characteristic electromagnetic features, namely zero direct current resistance and perfect diamagnetism. Zero resistance means that superconductors are ideal conductors, and there is no energy loss during electric energy transport using superconducting transmission lines. Moreover, supercon- ductors are more than just ideal conductors.
eBook - PDF- Patrick M. Woodward, Pavel Karen, John S. O. Evans, Thomas Vogt(Authors)
- 2021(Publication Date)
- Cambridge University Press(Publisher)
12 Superconductivity Superconductivity is the phenomenon whereby a significant number of elements and many compounds can conduct electricity with zero resistance below a critical temperature, T c , field, H c and current, J c . There are many technological applications for materials with this remarkable property and therefore a large global research and development effort in the area; around 7000 original research articles are published on Superconductivity every year. In this chapter, we will look at the history of Superconductivity and its physical origins in so-called BCS or conventional systems. We’ll then focus on the solid state chemistry of five distinct families of superconducting materials: A 3 C 60 alkali-metal intercalates, molecular superconductors, Ba(Pb,Bi)O 3 perovskites, the cuprate- or “high-T c ” superconductors, and the LaOFeAs-related “iron” superconductors. These families will highlight several recurrent themes and show how chemistry is used to prepare and tune superconducting materials. 12.1 Overview of Superconductivity The discovery of Superconductivity is a wonderful example of how “blue skies” research can lead to completely unexpected discoveries. In 1908, Heike Kamerlingh Onnes, a Dutch physicist working at the University of Leiden in the Netherlands, succeeded in liquefying helium. Access to liquid He, which boils at 4.22 K, allowed him to perform physical measurements on materials at much lower temperatures than previously possible. At that time, little was known about what would happen to the electrical resistance (R) of metals at very low temperatures.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 19 Superconductivity (Physical Chemistry) A magnet levitating above a high-temperature superconductor, cooled with liquid nitro-gen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (the Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet. ________________________ WORLD TECHNOLOGIES ________________________ A high-temperature superconductor levitating above a magnet Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, Superconductivity is a quantum mechanical phenomenon. It is also characterized by a phenomenon called the Meissner effect, the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that Superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics. The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (−183 °C).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 9 Superconductivity (Physical Chemistry) A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (the Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet. ________________________ WORLD TECHNOLOGIES ________________________ A high-temperature superconductor levitating above a magnet Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, Superconductivity is a quantum mechanical phenomenon. It is also characterized by a phenomenon called the Meissner effect, the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that Superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics. The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (−183 °C).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
_______________________ WORLD TECHNOLOGIES ______________________ Chapter- 4 Superconductivity A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (the Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet. _______________________ WORLD TECHNOLOGIES ______________________ A high-temperature superconductor levitating above a magnet Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes in 1911. Like ferromagnetism and atomic spectral lines, Superconductivity is a quantum mechanical phenomenon. It is also characterized by a phenomenon called the Meissner effect, the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that Superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics. The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (−183 °C).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 1 Superconductivity A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (the Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet. ________________________ WORLD TECHNOLOGIES ________________________ A high-temperature superconductor levitating above a magnet Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, Superconductivity is a quantum mechanical phenomenon. It is also characterized by a phenomenon called the Meissner effect, the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that Superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics. The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (−183 °C).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter-10 Superconductivity A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (the Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet. ________________________ WORLD TECHNOLOGIES ________________________ A high-temperature superconductor levitating above a magnet Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, Superconductivity is a quantum mechanical phenomenon. It is also characterized by a phenomenon called the Meissner effect, the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that Superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics. The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (−183 °C).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter-10 Superconductivity A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet (the Faraday's law of induction). This current effectively forms an electromagnet that repels the magnet. ________________________ WORLD TECHNOLOGIES ________________________ A high-temperature superconductor levitating above a magnet Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April, 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, super-conductivity is a quantum mechanical phenomenon. It is also characterized by a phenol-menon called the Meissner effect, the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that Superconductivity cannot be under-stood simply as the idealization of perfect conductivity in classical physics. The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. In 1986, it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (−183 °C).
eBook - PDF- Charles P. Poole, Horacio A. Farach, Richard J. Creswick(Authors)
- 2013(Publication Date)
- Academic Press(Publisher)
The Phenomenon of Superconductivity I. INTRODUCTION A perfect superconductor is a material that exhibits two characteristic properties, namely zero electrical resistance and per-fect diamagnetism, when it is cooled below a particular temperature T c , called the cnt-ical temperature. At higher temperatures it is a normal metal, and ordinarily is not a very good conductor. For example, lead, tantalum, and tin become superconduc-tors, while copper, silver, and gold, which are much better conductors, do not super-conduct. In the normal state some super-conducting metals are weakly diamagnetic and some are paramagnetic. Below T c they exhibit perfect electrical conductivity and also perfect or quite pronounced diamag-netism. Perfect diamagnetism, the second characteristic property, means that a su-perconducting material does not permit an externally applied magnetic field to pene-trate into its interior. Those superconduc-tors that totally exclude an applied mag-netic flux are known as Type I supercon-ductors, and they constitute the subject matter of this chapter. Other superconduc-tors, called Type II superconductors, are also perfect conductors of electricity, but their magnetic properties are more com-plex. They totally exclude magnetic flux when the applied magnetic field is low, but only partially exclude it when the applied field is higher. In the region of higher magnetic fields their diamagnetism is not perfect, but rather of a mixed type. The basic properties of these mixed magnetism superconductors are described in Chapters 9 and 10. II. A BRIEF HISTORY In 1908, H. Kamerlingh Onnes initi-ated the field of low-temperature physics 21 1 22 2 THE PHENOMENON OF Superconductivity by liquifying helium in his laboratory at Leiden. Three years later he found that below 4.15 K of the dc resistance of mer-cury dropped to zero (Onnes, 1911). With that finding the field of Superconductivity was born.
eBook - PDF- H.P. Myers(Author)
- 1997(Publication Date)
- CRC Press(Publisher)
13 Superconductivity It has been established beyond doubt that certain substances, when cooled below a critical temperature T c , completely lose all trace of electrical resistance in static electric fields: such materials are called superconductors. In a ring of superconducting material, induced currents persist for times as long as one has the patience to make measurements; the time constant of any decay of the current, which is controlled by L/R, where L is the inductance and R the resistance of the ring, is so large (of order 10 5 years) that we are justified in assuming that the resistance is truly zero. First discovered in 1911 in the metal mercury, we now know that under ordinary conditions of equilibrium, which is to say the ordered crystalline state and normal pressure, some 28 pure metals are superconductors, and other elements become superconducting under particular circumstances of high pressure (e.g. Ge) or structural disorder (e.g. Bi) (Fig. 13.1). For convenience, we shall use the letters N and S to denote the normal resistive and the superconducting states respectively. The N-S transition is, in pure strain-free single crystals, extremely sharp, occurring over 10 −4 K in some cases (Fig. 13.2). The critical temperature T c that marks the onset of Superconductivity in different pure metals ranges from near 0 to 9.2 K (Nb). Some 1000 intermetallic compounds and alloys become superconducting; certain of them have transition temperatures above 20 K and are used to produce powerful electromagnets. In 1986 a new class of superconducting material was discovered. These are mixed oxides of the form La 2−x A x CuO 4; A being an alkaline earth metal (originally Ba or Sr). Transition temperatures up to 125 K have been mea- sured (Table 13.1), and the associated critical magnetic fields are larger than hitherto observed. This discovery is promoting ever increasing activity in the development of such materials for new technical applications.
eBook - PDF- G Libowitz(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Materials Science in Energy Technology Chapter 10 Superconducting Materials for Energy Related Applications* T. H. GEBALLE DEPARTMENTS OF APPLIED PHYSICS AND MATERIALS SCIENCE STANFORD UNIVERSITY STANFORD, CALIFORNIA AND BELL LABORATORIES MURRAY HILL, NEW JERSEY M . R. BE AS LEY DEPARTMENTS OF APPLIED PHYSICS AND ELECTRICAL ENGINEERING STANFORD UNIVERSITY STANFORD, CALIFORNIA I. Introduction 492 II. The electrical and magnetic properties of superconductors 495 A. Type-I and type-II superconductors 496 B. The Ginzburg-Landau theory and the characteristic lengths of Superconductivity 500 C. The structure of the vortices and the critical fields of type-II superconductors 503 D. Surface effects 505 E. Vortex pinning and the critical state 506 F. Instabilities and ac losses 508 * Written under the support of the National Science Foundation, the U.S. Energy Research and Development Administration, and the Institute for Energy Studies at Stanford University. 491 Copyright © 1979 by Academic Press, Inc. All rights of reproduction in any form reserved. ISBN 0-12-447550-7. 492 T. H. Geballe and M. R. Beasley III. Occurrence and properties of important and potentially important superconductors 511 A. Ductile alloys 514 B. A15 compounds 520 C. Other high temperature and potentially important superconductors 534 IV. The state of the art 537 A. Composites for high field use 537 B. Superconducting power lines 542 References 547 I. I N T R O D U C T I O N Superconductors embrace a remarkable set of electric and magnetic prop-erties, the most startling being a total lack of dc resistance. Transitions into the superconducting state occur at a temperature T c , which may be from less than 0.01°K to a present-day high of 23°K. The potential of superconduc-tivity for important technological applications has tantalized scientists since the discovery of Superconductivity in frozen mercury by Kamerlingh Onnes in 1911.
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