S
Spehro Pefhany
Anyone have a number, in terms of RRR, for the plated copper purity?
TIA.
TIA.
Anyone have a number, in terms of RRR, for the plated copper purity?
Anyone have a number, in terms of RRR, for the plated copper purity?
TIA.
This has some lower temp values,
http://hypertextbook.com/facts/2004/BridgetRitter.shtml
Evidently, RRR(Cu) ~ 1.712 / 0.002 = 856, presumably for research purity Cu
(>4N???).
Tim
Fascinating. Regular copper at room temperature is already pretty
conductive. It must be scary at ~absolute zero, especially when very pure
(and, I might guess, single crystal as well?).
Heck, even if regular stuff is about 50, that's only 98% of the way to a
superconductor.
If a bar of copper at STP can hold a magnet with a ~seconds
time constant, really cold, pure copper must do a pretty good magnetic
levitation trick all its own!
Tim
Spehro Pefhany said:Copper _never_ goes superconducting, interestingly. Lots of elements
do, but not Cu, Au or Ag. Aluminum does weird stuff.
Sort of. As I think of it, a superconductor has infinite conductivity,
so you can't get halfway there.
Interesting idea. Skin effect starts to become important at much lower
frequencies.
This has some lower temp values,
http://hypertextbook.com/facts/2004/BridgetRitter.shtml
Evidently, RRR(Cu) ~ 1.712 / 0.002 = 856, presumably for research purity Cu
(>4N???).
Tim
Electro-depositing copper can produce very high levels of purification.
Physicists doing very low background counting experiments, for example
looking for double beta decay in the Homestake gold mine 5000 ft below
ground make the Dewars to hold high purity germanium crystals using
electrodeposition of copper. Even starting with technical grade copper
sulfate, the electroplated copper had orders of magnitude less radioactive
impurities than most other materials.
Bret Cannon
Spehro Pefhany said:On Tue, 17 Jul 2012 22:27:58 -0700, the renowned "Bret Cannon"
Isn't the copper that wire is drawn from "electrolytic"?
Best regards,
Spehro Pefhany
I think I saw a plot where really pure aluminum had a resistivity
lower than copper at LN2 temperatures. So a neat demo is to drop a
magnetic onto a plate of aluminum in a LN2 bath. A nice soft
landing!
George H.
Anyone have a number, in terms of RRR, for the plated copper purity?
TIA.
Isn't the copper that wire is drawn from "electrolytic"?
Best regards,
Spehro Pefhany