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Susan Rambo
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Re: Very Clear
Susan Rambo   5/28/2014 1:40:06 AM
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Good advice.

Les_Slater
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Room temperature?
Les_Slater   5/27/2014 11:00:37 PM
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I went to a presentation by Dr. Paul Chu of the University of Houston, somewhere in the late 80's, on 'room temperature' superconduction. There were no usable high temperature materials that could carry current without any electrical resistance but some materials contained surface islands that exhibited the Meissner effect at much higher temperatures than normal transition temperatures.

sixscrews
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Re: Very Clear
sixscrews   5/27/2014 6:33:32 PM
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To clarify the temperature issue, the article contains the line: "materials eventually become superconducting below roughly -400 degrees Fahrenheit."

-400 F ~ 33 K ~ -240 C

This is above the boiling temperature of liquid helium at 1 atmosphere (4.2K) but below the boiling temperature of liquid nitrogen (77 K ~ -196 C ~ -321 F). 

It's also below the boiling temperature of argon at 1 atm (87K).

So it's not quite as nifty a superconductor as the YBaCuO (Perovskite) discovered by Bednorz and Muller in 1986 and commercialized by a number of companies since then.  Some of the superconductors in this family can operate around 77 K (i.e., LN2 boiling temperature) but they work better at lower temperatures.

The YBaCuo and related materials have found uses as current leads in persistent DC magnets used in MRI machines and as mid-temperature (but still cryogenic) connectors in high energy physics magnets and they have also been applied as AC and DC power conductors, albeit over short hauls (hundreds to thousands of meters).

To date no company has managed to catch the golden ring of superconductors but an awful lot of money - private and Government - has gone into their development.

The Argonne work is significant in that it demonstrates the presence of a previously unrecognized magnetic phase in particular metallic compounds.  I do not read it as a significant step in superconductor work - there is a lot more to be done before the observed phenomenon can be commercialized - and it'a hard to see just what commercial products will result.

Related work lead to the development of GMR heads for magnetic storage media some 20-30 years ago - and serveral orders of magnitude increase in storage density of rotating media.

What's next?  Who knows - but, as another poster advised, stay away from Kickstarter projects promising room temperature superconductors....

ss/wb

DrFPGA
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Re: Very Clear
DrFPGA   5/27/2014 1:44:02 PM
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Avoid any kickstarter room-temp superconductor start-ups would be my advice...

DeeCee430
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Re: Very Clear
DeeCee430   5/27/2014 1:16:40 PM
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The article in http://www.superconductors.org/77C.htm says "77 Celsius (170F, 350K)"

wilber_xbox
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Re: Very Clear
wilber_xbox   5/27/2014 1:12:07 PM
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is it 77C or 77K or -77C?? Need little clarification as superconductor at 77C will be amazing.

DeeCee430
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already in operation
DeeCee430   5/27/2014 12:51:14 PM
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While the article says that superconductors are not currently used for power transmission lines, there are actually several already in operation.  However, they are fairly short:
  http://www.extremetech.com/extreme/182278-the-worlds-first-superconducting-power-line-paves-the-way-for-billions-of-dollars-in-savings
  http://en.wikipedia.org/wiki/Holbrook_Superconductor_Project
  http://www.powerengineeringint.com/articles/print/volume-21/issue-5/features/superconductors-are-ready-to-relieve-urban-congestion.html



Martini Tech
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Re: Very Clear
Martini Tech   5/27/2014 12:31:04 PM
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This guy here (http://superconductors.org/) is claiming to have candidates at 77C, but I do not know how much he can be reliable..  

DrFPGA
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Very Clear
DrFPGA   5/27/2014 12:15:53 PM
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Thanx for the excellent summary of superconductivity! Maybe there is a room temp combination here someplace...



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