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Superconductivity in pyrolytic graphite?

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LAN_403

Conundrum

Sat Apr 12 2014, 02:12PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Hi, this is interesting. A few years ago a guy named kawashima in Japan claimed that pyrolytic graphite soaked in heptane could exhibit significant signs of room temperature superconductivity.

I tested a piece this morning using 80% acetone and 20% MEK for gluing pipes and the resistance did drop significantly but more interestingly it also failed to levitate over a halbach array until all the MEK evaporated. I don't think this has been documented anywhere before and if so then pure MEK might yield interesting results and be easier to duplicate..

The levitation effect seemed to coincide with a change in colour of the graphite from flat black to shiny black as it jumped off the magnet.. I haven't seen this happen with either pure acetone or naptha.

Going to try a proper 4 point test to see what happens, it's worth mentioning that the supplier sent me this sample full of bubbles which might adversely change the structure.
Perhaps this allows the solvent inside the graphene layers causing a change in resistance?

Andre

Sulaiman

Sat Apr 12 2014, 02:35PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

maybe your graphite is acting like a sponge, absorbing the MEK so heavier?
try a similar weight of water to see if the mass is the main variable
or 'the liquid just 'sticks' the graphite to the magnets until evaporated off?

Conundrum

Sat Apr 12 2014, 02:51PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Worth checking. I didn't notice this effect with any other solvent though.
Do you have any ideas for attaching probes to the graphite that wouldn't fall off in a solvent?

Forty

Tue Apr 15 2014, 10:02AM

Registered Member #3888 Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649

acetone and MEK are quite polar and Heptane is totally nonpolar. I wouldn't expect them to have similar effects on the graphite.

Sulaiman

Tue Apr 15 2014, 02:18PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

I occasionally use silver-loaded adhesive,

just the tiniest drop would physically & electrically connect a wire to almost any solid.
Once dry it seems fairly solvent resistant.

If you get some you could see if it has any interesting effects with graphite
(doubt it but who knows?)

Patrick

Tue Apr 15 2014, 11:07PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Can we see your halbach array and related materials ? With ruler present.

Sulaiman

Wed Apr 16 2014, 08:26AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

for levitation of graphite (does not need to be pyrolytic, graphite foil works too)
I have had best results with a simple chequerboard pattern with a steel plate base.
e.g.

NSNSNS
SNSNSN
NSNSNS
SNSNSN
NSNSNS
SNSNSN

Conundrum

Wed Apr 16 2014, 06:22PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Yes this is what I used.

I have since found something interesting, solvents sold for a specific purpose sometimes have other stuff in the mix which can be quite varied but does not need to be declared on the label (!)

Even more interesting, it appears that the original results Mr. Kawashima reported have been replicated but only some samples exhibit the effect and the usual culprits (ie iron or other paramagnetic materials) don't seem to be as much of an issue.
It could be that more is going on here than first appears which explains the problems others have had replicating the effect ie zero resistance at room temperature.

My hypothesis is that the graphite isn't actually the source of the anomalous high conductivity, but something in (a) the interface between the grains or (b) some other contaminant such as strontium titanate present in the lab.

-A

Andy

Wed Apr 16 2014, 11:02PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Conundrum
Might be interesting

Mentions graphene instead of graphite but thought it might be related

Conundrum

Fri Apr 18 2014, 06:52AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Thanks!

So many projects, so little time...
See

I need to set up a proper 4 point test, it seems regions of this sheet have far more of an effect than others.

EDIT 26/08/2014 I tried the same experiment with the same setup and a heptane containing solvent, no effect whatsoever.
Not sure why, perhaps it has to be pure heptane to have an effect ?

Will try again with a mixture of heptane and MEK to see if there is any effect, perhaps the MEK does something to the graphite that makes it more sensitive to the other components of the solvent?

EDIT 03/09/15
Yeah, saw this ages ago. the problem seems to be that it only happens in very specific graphite samples. i found that my PG only worked with one of five pieces from the ebay seller and only a freshly thinned surface. It occurs to me in the light of the recent articles that perhaps lithium or some other light metal was the catalyst, present as an impurity and hydrogen from the solvent might have stimulated high frequency oscillations in the lattice as Ashcroft originally suggested in 1967 with metallic hydrogen. Indeed now recall tinkering with lithium coin cells around the same time so it could have left tiny traces on the end of my meter probe(s).

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