Superconductors that possibly work at room temp.

Anonymous Coward writes "University of Houston, Texas researchers have found subtle signs of superconductivity in nanotubes of carbon. They may conduct electricity without any resistance, at temperatures stretching up past the boiling point of water. See the story on EurekAlert"

Comments

So...

[Jeremiah Cornelius]

We make a GIANT nanotube, and power the whole city!

The repugnant stench of New Scientist.

[deglr6328]

Looking closely at the bottom of the page reveals the article's infamous origin:

"PLEASE MENTION NEW SCIENTIST AS THE SOURCE OF THIS STORY AND, IF PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO: www.newscientist.com"

You see, New Scientist is a tabloid like sensationalistic uncredible rag. Trusting scientific information from New Scientist is like asking your auntie May who's an LPN to perform brain surgery on you.

For instance one glaring oversight in the article:"To decide whether or not the nanotubes really are superconductors, you need to measure the resistance through a single tube, Alexandrov says."

Alexandrov is apparently the only theoretical physicist left in the world who didnt see the Science article 6 months ago finding that nanotubes superconduct. He also incorrectly states that "Superconductivity theories do not forbid the phenomenon at very high temperatures" this is totally incorect. Type one superconductors have a limit of about 40K and there are theories placing the upper limit of type II superconductors at 200K.

...magnetic field??

[Transcendent]

"For example, when the researchers put a magnetic field across a bundle at temperatures up to 400 kelvin (127 C), the bundle generated its own weak, opposing magnetic field. Such a reaction can be a sign of superconductivity."

Correct me if I'm wrong, but I thought that all current carrying deviced generated their own opposing magnetic field.... even the wires going through most all buildings. The strenght of this magnetic field would allow us to calculate the resistance in the conductor, them stating that it produced a weak magnetic field doesn't prove much...

Done that...

[zhiwenchong]

Researchers in Fairbanks Alaska announced last week that they have discovered a superconductor which will operate at room temperature.

Close, but not quite.

[caffeinated_bunsen]

All conductors oppose changes in magnetic fields by having currents induced which try to preserve the original magnetic flux through the conductor. If there was no magnetic field, and you turn one on, a current will be induced so as to oppose the field. In a non-superconductor, those currents don't flow for very long before ohmic resistance does its thing. In a superconductor, they flow until the external magnetic field is removed, and the original flux is achieved without an induced current.

Persistent currents, on the other hand, are created when you cool a superconducting ring (doesn't work with solid chunks because of the Meissner effect) below its critital temperature in a magnetic field, and then remove the external field. The superconductor has to maintain whatever magnetic flux through the ring that was present when it became superconducting, so a current is induced that mimics the external field. That current stays around until either the original external magnetic field is restored or the material ceases to be superconducting.

And I'd damn well better know what I'm talking about, since this will be on the final in 2 weeks.

(I didn't bother with much detail about the Meissner effect and its consequences. If you're confused about the persistent current part, I can explain that in detail.)