Superconducting Materials
A superconductor is a substance which is very-nearly 100% efficient in regards to the transfer of electricity, even over vast distances. The very first superconducting material was discovered (the element, mercury!) in 1911, but the superconducting property could only be obtained at temperatures below the boiling point of liquid helium. How cold is that? - Just above absolute zero, which is the coldest temperature possible! The discovery of a superconducting material is exciting, but the liquid helium requirement meant that its practical use was not possible (due to extreme costs of cooling equipment and liquid helium itself).
Since 1911, scientists in private and public (academia and national laboratories) research institutions have worked to develop materials which are superconducting at much higher temperatures.
The Importance of High Temperature Superconductors (HTSC's)
The invention of the three-phase alternating-current (TP-AC) electrical distribution system in the early 1900's was a huge leap forward for mankind, enabling very many conveniences and technologies of modern society. <Brief Side Notes>The TP-AC system was invented by, none other than, Nikola Tesla. This fact may be surprising because it seems that most people believe Thomas Edison invented the TP-AC system, but this is far from the truth. Actually, Edison invented a direct current (think batteries and power packs) distribution system, which was quite important, but impossible to use over long distances, due to the requirement of massive cables and huge safety hazards (such as a tendency to overheat, resulting in destructive fires).<End - Brief Side Notes>
As marvelous as our TP-AC systems are, there is an issue which continues to this day; power losses over long distances, mainly due to an inherent resistance to electrical flow within high-voltage lines. But, what if a material existed, with practically no energy losses upon electrification over great distances?!; Candidate number 1 - HTSC's! The practical use of HTSC's in the form of long distance high voltage power lines would be nothing short of revolutionary, on a level not seen since the invention of the TP-AC system itself!
Recent Advances in HTSC Materials Research
Fairly recent discoveries of new ceramic materials have resulted in HTSC's allowing much higher temperatures to obtain super-conduction. Major breakthroughs in the production of HTSC's began in 1986, with the synthesis of Lanthanum Barium Copper Oxide (LBCO). LBCO has superconducting properties at a "balmy" 35 Kelvin (-238 deg. Celsius), but still too cold for practical applications. Only a year later, building on the technology of LBCO, Yttrium Barium Copper Oxide (YBCO) was synthesized at the University of Houston. YBCO was a major advancement in that it is superconducting all the way up to 93 Kelvin! Finally, a superconducting material was available which could be cooled with Liquid Nitrogen; a relatively inexpensive and plentiful substance with a boiling point of 77 Kelvin. As of this writing advances continue, with critical superconducting temperatures as high as 133 Kelvin attained. Since the 1980's, the search is still on for HTSC's working at significantly higher temperatures, with the "holy grail" being superconductivity at room temperature. Additionally, a superconducting "wire" has been developed by powder-coating a durable substrate with YBCO. Currently (pun intended, I suppose), superconducting technology is being used to operate the "Mag-Lev" high speed commuter train based in Japan!
The Crystal Lattice Structure of YBCO and Theory of Conduction
The below diagram shows a small section of YBCO crystal. Scientists have discovered alternating layers of charge-conserving and charge-transfer regions throughout the lattice structure. The property of the layers and resulting facilitation of superconduction seem to result from oxygen atoms in a state of dynamic equilibrium between insulating and conducting layers of cuprate groups. According to the Matts theory, the transfer of "holes" (electron vacancies) from the charge layer into the conducting layer causes electrons spins to pair up. This decreases the energy state of electrons and greatly lowers resistance to their transfer through the structure.
References
"Superconductivity - Wikipedia, the free encyclopedia." 2004. 22 Feb. 2014 <http://en.wikipedia.org/wiki/Superconductivity>
"'Long-awaited explanation' for mysterious effects in high ..." 2013. 22 Feb. 2014
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That's all for now. Thank you for reading!
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