In 1911, Dutch physicist Heike Kamerlingh Onnes discovered that the resistance of mercury absolutely disappears at temperatures below about 4K. This phenomenon is called superconductivity; correspondingly, materials which have this property would be called superconductors. Because of this great discovery, in 1913, he won a Nobel Prize in physics for his research in this area.
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The technological development of superconductivity was hampered by the cost of producing the extremely low temperatures required to achieve the effect. Until 1986, new superconducting ceramic materials were discovered which have considerably higher critical transition temperatures. Gradually, as more and more metals, alloys, and compounds are found to have superconductivity and be cheap to produce, the practical application of superconducting devices at room temperature may eventually become commonplace. Excellent properties and attractive prospects of superconductors have been found since the day they were discovered.
Superconductors have been used in many fields in recent times, and this paper will mainly discuss the classifications, properties, applications, etc., to help people understand
Da Wang, Jack
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superconductors better .
2. Classification
2.1 Sorted by Material:
Superconductors can be made from some pure elements, such as mercury and lanthanum, and some allotropes of carbon, such as graphite.
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Some alloys such as
Niobium-titanium
[5] also have superconducting properties. Ceramics can be used as superconductors as well, such as yttrium barium copper oxide (YBCO) family.
2.2 Sorted by The Meissner Effect
:
Type-I Superconductors:
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Type-I superconductors all show the similar magnetization curve in a magnetic field, as shown in figure 1: ...
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...e amount of Ic that passes through each unit cross-sectional area of the superconductor is called the critical current density, which is represented by Jc.
All of these critical values severely restrict the conditions for using superconductors, and thus finding new superconductors with higher tolerances has become an important research topic for scientists. For example, from 1911, when Dutch physicist Kamerlingh Onnes discovered superconductivity of mercury (Tc = 4.2K), to 1986, the highest Tc found was 23.2K
(Nb3Ge, 1973). In 1986, Swiss physicists Bednorz and Müller discovered superconductivity in a lanthanum-based cuprate perovskite material, which had a Tc of 35 K.
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And only after one year, the new record of Tc has reached about 100K. This breakthrough has opened up a bright future for the application of superconductors. This led to Bednorz and Müller winn
The "2nd U.S. Circuit Court of Appeals" held that those business practices that have had a disparate impact effect on the older workers are now considered to be actionable under one national anti-discrimination law (Hamblett, 2004). The case does reaffirm a second Circuit precedent that had been set but which is at odds with what a majority of federal courts have held. The appeals court supported the idea that a layoff plan had been properly brought under the The Age Discrimination in Employment Act of 1967 (ADEA) although the company did not have the intention of discriminating.
2. Liang Chi Shen and Jin Au Kong, Applied Electromagnetism, 3rd ed. PWS Publishing Company, 1995.
In 1934 the American scientist Harold Clayton Urey won the Nobel Prize for chemistry for his discovery of the heavy form of hydrogen known as deuterium.
Transition metal oxide (TMO) materials contain transition element and oxygen. Both insulator and metal of poor quality are belongs to this group. It may be happens that the same material may give both types of transport properties. When either temperature or pressure is varying, then metal-insulator transition is possible. There are few superconductors are transition metal oxide. Valence electrons are present more than one shell in such type of compound. But the most of transition metal has one oxidation state. Transition metal oxides are not associated with activation energy; hence it is better than non-transition metal oxides. Transition metals have vacant d orbitals, so they are basically called catalyst. The metal surface adsorbed the reagent and the substrate and reagent are bound between them by a clamp called d orbitals. The vacant d-orbitals behaves similar like energy gap, hence transition metals have different colours.
Abbott, M., Lin C., Martian, P., Einerson, J. (2008). Atmospheric mercury near Salmon Falls Creek Reservoir in southern Idaho. Journal of International Association of Geochemistry. Volume 23 issue 3. www.sciencedirect.com/science/article/pii/
Michael Faraday was born on September 22nd, 1791, at Newington in Surrey, England to a Sandemanian family (Crowther, 7). The Sandemanians were an almost unknown off-shoot of the Presbyterian Church. Faraday was baptized in the Church but only became an official member in 1821. His religion was an important part of his life, though it featured little in his work (Crowther, 25-26 and Day, 28). From an early age Faraday showed a passion for facts and distrust for authority, two qualities that would later on characterize his scientific studies (Crowther, 9). He always had to see something occur for himself before putting any stock in it. He repeated experiments he saw in scientific books and journals to convince himself of their veracity. His first professional foray into the field of chemistry was in 1813 as an employee of the famous Sir Humphrey Davy at the Royal Institution in London (Crowther, 12). It was Faraday's enthusiasm for science which helped him attain the position for, till that time, he had been well on the way to a career as a bookseller. He eagerly went to work on his passion. His first published paper, "An Analysis of Naturally Occurring Caustic Lime" appeared in the Quarterly Journal of Science in 1816 (Crowther, 19).
Superconductivity, a similar phenomenon, was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. When he cooled some mercury down to liquid helium temperatures, it began to conduct electricity with no resistance at all. People began experimenting with other metals, and found that many tranisition metals exhibit this characteristic of 0 resistance if cooled sufficiently. Superconductors are analagous to superfluids in that the charges within them move somewhat like a superfluid - with no resistance through sections of extremely small cross-sectional area. Physicists soon discovered that oxides of copper and other compounds could reach even higher superconducting temperatures. Currently, the highest temperature at wich a material can be superconductive is 138K, and is held by the compound Hg0.8Tl0.2Ba2Ca2Cu3O8.33.
electricity and the physics of electricity. For the areas of science in which he worked, he is known for
Heike Kamerlingh Onnes was studying superconductivity. Onnes was researching the properties of matter, but not in the normal state. He had the temperatures extremely low and he observed the properties of matter. At the end of his investigation, his result were remarkable he created liquid helium… he then received a nobel for his great discovery.
The largest and most powerful particle collider in the world, based in CERN on the border of France and Switzerland, it is a huge undertaking. It is built to assists the scientists in discovering what the Earth is made of; it also plays a crucial part in resolving many theories by scientists. It is a 27 kilometer ring with super magnets that help the particles speed along the way. Some people also argue that it’s a machine that could possibly be dangerous, because it has the capability of creating small BLACK HOLES! “One way or another, it's the world's largest machine and it will examine the universe's tiniest particles. It's the Large Hadron Collider (LHC).”
Traditionally in school we are taught that there are only four states of matter: solid, liquid, gas, and plasma. Fortunately this is not true as that would be boring. There are also at least 4 other-less common states and Icontest a fifth. These are Bose-Einstein condensate, photonic molecules, quark-gluon plasma, superconductors, and superfluids. They all have unique properties that clearly distinguish differences between them and the traditional four states. These breakthroughs could help us in the future and have some practical uses right now.
Serway, Raymond A, and Robert J Beichner. Physics: For Scientists and Engineers. United States of
"The Nobel Prize in Physics 1921". nobelprize.org. Nobel Media AB 2013. Web. 24 Feb. 2014.
The development of superconductors has been a working progress for many years and some superconductors are already in use, but there is always room for improvement. In 1911, Dutch physicist Heike Kamerlingh Onnes first discovered superconductivity when he cooled mercury to 4 degrees K (-452.47º F / -269.15º C). At this temperature, mercury’s resistance to electricity seemed to disappear. Hence, it was necessary for Onnes to come within 4 degrees of the coldest temperature that is theoretically attainable to witness the phenomenon of superconductivity. Later, in 1933 Walter Meissner and Robert Ochsenfeld discovered that a superconducting material will repel a magnetic field. A magnet moving by a conductor induces currents in the conductor, which is the principle upon which the electric generator operates. However, in a superconductor the induced currents exactly mirror the field that would have otherwise penetrated the superconducting material - causing the magnet to be repulsed- known today as the “Meissner effect.” The Meissner effect is so strong that a magnet can actually be levitated over a superconductive material, which increases the use of superconductors. After many other superconducting elements, compounds, and theories related to superconductivity were developed or discovered a great breakthrough was made. In 1986, Alex Muller and Georg Bednorz invented a ceramic substance which superconducted at the highest temperature then known: 30 K (-243.15º C). This discovery was remarkable because ceramics are normally insulators – they do not conduct electricity well. Since their discovery the highest temperature for superconductivity to occur is 138 K (-130.15º C).
The research that established Faraday as the foremost experimental scientist of his day was, however, in the fields of electricity and magnetism. In 1821 he plotted the magnetic field around a conductor carrying an electric current; the existence of the magnetic field had first been observed by the Danish physicist Hans Christian Oersted in 1819.