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Diamonds As Room-Temperature Superconductors
Stormalong writes "This article describes research into using diamonds as room-temperature superconductors. If successful, perhaps one day you could give your love a diamond engagement CPU instead of a ring!"
SciFi Today ran this story a couple of days ago with LOTS of interesting extra links here.
I got this from one sentance: Current continues to flow from the diamond cathode through this layer to the anode, even though there is no voltage across the layer - a sign of superconductivity.
Room temp superconductivity is nifty. What's (literally) incredible is that the guy is claiming to have produced "Bose-Einstein-type condensate" at room temperature, as opposed to the usual few-billionths of a degree above absolute zero.
I find "experimental error" to be far more plausible, but of course it's hard to know without seeing both the original researcher's work as well as third-party confirmation results.
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The single most important development that would come out of a room-temperature superconductor would be the elimination of batteries, fuel cells, gas tanks, and every other such power storage technology.
Because a superconductor conducts with literally zero resistance, you can create a ring of superconducting material, pump as much current into it as it will tolerate, and just let the current cycle forever. No degradation whatsoever. Then when you want power, you just tap into the ring and pull it out on demand. Superconducting rings are real devices, by the way -- they're just big and expensive and require cryogenics.
If we could make them out of something that operated at room temperature, then we could (probably) make very small superconducting rings, and if the power density were high enough, we could use them instead of batteries or fuel tanks. And they would never, ever wear out, no matter how many times you charged or discharged them. The amount of power they could contain is dependent on the superconducting material in question, but a high-power-density room-temperature superconductor (if such a thing is possible) would eliminate all of mankind's power storage and transmission problems. The only concern left would be generation.
ZFS: because love is never having to say fsck
They glow because they're doped--rubies were shown on a PBS show a few years back. Lab created gems are generally doped with elements to make them distinguishable somehow--don't think scientists and engineers don't get bribed to produce a perfect gem.
Yes, single crystal 'gems' created in the lab are for all intents and purposes, perfect, they have to be to be used in any experiment concerning the creation of semiconducting devices.
It probably would NOT change the gemstone market due to cost of growing diamonds. IIRC, CVD (Chemical Vapor Deposition) is currently the only way to produce diamonds for manufacturing. This is in no way as cheap or easy to do is pulling a 'perfect' silicon ingot out of a molten bath.
So, when's lunch?
Remember, the next time you buy a diamond for your sweetie, slave (and probably child) labor, blood, sweat and tears literally goes into each one. Ahh...nothing says love like the suffering of your fellow man. If this concerns you, then you should probably buy Canadian Arctic Diamonds which are exploitation- and conflict-free.
This is known as Wiedeman-Franz Law in Physics. It describes the relationship between eletron heat transfer and conductivity. However it is only valid for Metals. Heat transfer in semiconductors is dominated by lattice vibration transport. Due to the bandgap there is little phonon/electron interaction.
A notable exception is diamond with a low electrical conductivity on the order of 1 S/m and a high thermal conductivity of 700 W/mK.
Its not an exception, its a semiconductor with a large bandgap and behaves exactly as expected.
The article skimped out on theoretical details, but the Bose-Enstein-type condensate refers to the superconducting phase-transition where the electrons form Cooper-pairs (through an electron-lattice-electron interaction). These Cooper pairs are spin-zero (the electrons pair anti-symetrically into the singlet state), and act like bosons, which can condense into the Bose-Einstein condensate.
Note that this is NOT exactly like a Bose-Einstein condensate because the bosons themselves contain two fermions, which are effectively coupled. These are similar, but not the same as the rubidium atoms in the BEC experiment you linked to. So it is kind of a BEC, but not exactly.
Now regarding your mention of a few-billionths of a degree above absolute zero, that is for the rubidium-atom experiment. THe superconducting phase-transition, which is what this article was referring to, happens in many elements at a few Kelvins, and in High-Tc materials up to the record of 150 K (I think).
Beyond that, there is other stuff that is sketchy, such as the professor retiring and not verifying that the diamond superconductors demonstrate the Meissner Effect (magnetic field expulsion from the interior of a superconductor) and other things. If this was really superconducting, I'd be sure he'd stay on as emeritus for at least a few years and keep going with these experiments, where he has a head-start over all other groups. If this is really room-temp Tc material that the article purports it to be, then this is HUGE news, and he should stay emeritus than quit research entirely. Hmmm...
make world, not war
Yikes. If you try to "tap in" to an inductor, it will produce an enormous voltage and immediately arc to close the circuit. The only way to get energy out of a superconducting solenoid is through some magnetic interaction.
If you pick the number of windings carefully, tapping directly into the inductor works just fine.
The inductor wants to maintain the current flowing through the coil. If that is the amount of current you expect to draw for your load, both load and coil will be perfectly happy in the new configuration. If you wish to draw less current (or tolerate interruptions without arcing), drop a resistor in parallel with the load. This will limit voltage across the load to the amount needed to push the coil's current through the resistor.
When you aren't using the load, of course, you short across it so as to reduce resistive power loss. Typically this switching is actually performed by having a closed coil, and heating the part you want to cut out above the superconducting breakdown temperature, if I understand correctly.
The only design difficulty is that this requires a large number of windings (sheet current is typically millions of amps or more, which means you need millions of windings for a load that draws 1A).
Did you know that the entire U.S. electrical grid could be powered by less than 150,000 modern wind turbines?
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I did not know this, so I did some quick googling and found some interesting numbers. According to the DOE the total U.S. generation of electricity for 1999 was 3691 billion kilowatt hours.
http://www.eia.doe.gov/cneaf/electricity/epav1/
According to the Danish Windpower Industry Association, a modern wind turbine will generate about 2 to 3 million kilowatt hours of electricity per year.
http://www.windpower.org/faqs.htm#anchor727849
If these numbers (and my math) is right, your conclusion is off by about an order of magnitude
Superconductors have a number of important uses in analytical instruments, too. A superconducting magnet sits at the heart of most nuclear magnetic resonance machines, as such magnets are capable of carrying enormous currents with almost no resistance, enabling them to produce magnetic fields of over 20T (400,000 times the strength of the magnetic field of the earth). Most of these magnets are made from alloys of niobium, with critical temperatures (the temp below which superconductivity occurs) around 23 Kelvin, meaning they need liquid helium to cool them. I happen to have a student job dispensing cryogens for research groups on campus- we charge about 4 bucks a liter for liquid helium, and some groups will go through a full 65L dewar in a couple days. Efforts have been made to move to the Type II (cuprate ceramic) superconductors discovered in the late 1980s, but as others have mentioned, ceramic can't be extruded into wire the way most metals can. Still, there is significant financial incentive to use Type II materials- liquid nitrogen, which boils at 77K, only costs about 20 cents per liter. Of course, with a room-temperature superconductor, there would be no cooling expenses, and there would also be no need for bulky cryostats surrounding equipment- it's likely we could see mobile MRI and NMR machines.
In addition to their uses as magnetic coils, superconductors can be used to exploit something nifty called the Josephson effect: if you separate two superconductors by a tiny insulating gap, a supercurrent of Cooper pairs can quantum tunnel across the gap. This effect can be used in a device known as a SQUID (Superconducting QUantum Interference Device), which is essentially a fantastically sensitive magnetometer- some SQUIDs can detect fields of less than a picotesla. This has already had important applications in materials science- there are scanning-SQUID microscopes, and is finding a number of uses in medicine- specifically measuring the magnetic activity of the brain and heart. Also, SQUIDs will probably have a future in computers, as hyperfast switches, sensitive hard disk heads, or as sensors used in quantum computers, detecting the state of a qubit. IBM tried to make a computer using Josephson junctions as switches back in the late 1970s- there were a number of hurdles that prevented this device from becoming a reality, mostly the incredible rate at which "conventional" silicon chip ICs were improved, and the fact that this conventional technology does not require you to immerse your computer in liquid helium.
And yeah, there could finally be maglev trains- those operate off of the Meissner effect, discovered in the 1930s- superconductors are perfectly diamagnetic- they will expel any external magnetic field, causing the magnet (or superconductor) to be levitated. This is the effect that the scientist who observed the possible diamond RTS admits he has not done experiments to check, and it's the effect I'd really need evidence of in order to believe his findings.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
Well, first off, as someone else pointed out, I should have said 1.5 million turbines, not 150,000, so as not to assume constant peak output as I had mistakenly done. However, each one of those turbines takes only 36 square meters, meaning that all 1.5 million would take less than 14,000 acres, or about as much oak forest that is lost each year in California alone, or less than twice the area of the Stanford University campus.
That power costs about 4 cents per killowatt hour, compared to 3 cents for poorly-scrubbed coal (compared to European scrubbing standards, which result in 4 cents/kwh), anywhere from 7 to 15 cents per kilowatt hour for natural gas (depending on market rates with occasional shortages) 11 cents/kwh for nuclear (plus hidden externalities for waste disposal). In other words, it's the best deal around.
Right, you hit the nail on the head for the 150,000 figure. Again, I should have said 1.5 million for average output values. The occasional drop caused by widespread windlessness could be backed up by hydroelectric power stations, or storage systems.
The diamonds we see in jewelery are far from the only diamonds out there. After a diamond is mined, only a certain few are good enough quality for that, and the vast majority are considered "industrial grade," for use in cutting tools, etc.
AFAIK, man-made diamonds are never good enough for jewelery and are alwasys considered industrial grade.
On top of that, most of the price of diamond jewelery comes not necessarily from the stone but the skill that went into crafting it. The person shaping the stone has to deal with not only trying to carve the hardest stone known to man (where those "industrial grade" diamonds show their usefullness), but one mistake pretty much ruins the stone entirely.
Uh, What?. Synthetic gemstones are chemically indistinguishable from the real thing. For a while, the distinguishing characteristic of lab created gemstones was their remarkable lack of defects. However, enterprising companies that make synthetic stones have figured out how to include the defects that you normally see in natural stones. So you can no longer tell the difference. There is no law to require they be marked, and there is no inscentive for the manufacturers to do so. If you saw stones that glowed, they were probably made that way for industrial use. Ti-doped Sapphire (Al2O3) is used for "tunable" lasers, for example. In fact, the first laser was made from ruby (Cr-doped Sapphire). These days people can make synthetic sapphires the width of a telephone pole and several feet long. They are used as windows on the barcode scanners in the supermarket because sapphire is much more scratch resistant than glass.
Frankly I don't understand why people value stones that were dug up out of the ground more than ones created in the lab. It's not like there is a real difference. Besides, if you actually visited a gemstone mine, you would probably lose all the romantic ideas you have about the origin of the stones.
As far as synthetic diamonds go, there are several possible ways to produce them. CVD is commonly done to produce diamond films for research. GE Superabrasives produces industrial diamonds using a high pressure process for decades. The diamonds are small, but they are cost effective. GE also produces "clarity enhanced" diamonds. They take natural diamonds that are lousy color and treat them to make them a more appealing color. Can you tell? I doubt it.
I'm a materials scientist, and I suspect that synthetic diamonds are less than a decade off. When that happens, the whole house of cards that is the diamond industry will come crashing down. Diamonds are not rare, but DeBeers controls most of the supply. When they loose that control, diamonds will crash to a price befitting their rarety.
And don't go around thinking that diamonds have ever been a good investment. The vast majority of diamonds actually depreciate relative to inflation.
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The internet is the greatest source of biased information in the history of mankind.
Me too. I managed to talk my wife out of getting a diamond on ethical grounds. We went with moissanite instead. Her ring has a green moissanite flanked by two clear moissanite stones.
The funny thing about clear moissanite is that people refuse to believe it is not diamond, even when they are told directly. Moissanite actually has a higher index of refraction than diamond, and so it sparkles more! Plus, moissanite only costs one tenth as much as an equivelant quality diamond. Most people have never heard of it, because it is not a naturally occuring stone. The plus side to that is that I can definitively say that I know the stones came from a factory in North Carolina. Can you tell me where your diamond came from?
You can tell the difference under a jeweler's loop (if you know what you are looking for, moissanite is birefringant), but moissanite will actually fool the cubic zirconia testers that most jewelers use.
In the interest of full disclosure, I do own some stock in the company that makes moissanite. I bought the stock because I was impressed with the product, but you are welcome to take everything I say with a grain of salt.
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The internet is the greatest source of biased information in the history of mankind.
It is apparently quite easy to tell these diamonds from natural diamonds. I saw a program on this not that long ago. Any competent jeweler could easily tell the difference:
1) Man-made gem-stone quality diamonds are generally too perfect.
2) These diamonds generally have non-natural coloring. Some are actually artificially colored (sky blue diamonds anyone?)
3) These diamonds fluorese under UV "Black" light.
As I understand it, one of the big goals for these guys (besides breaking the DeBeers distribution barrier) is to make the diamonds as 'real' as possible. So, they are working on ways to introduce flaws and color variations into the stones. I got the feeling from the program, they aren't that far away from their goal of manufacturing a 'natural' diamond.
DeBeers is so worried about the whole situation they are now micro-etching the DeBeers logo onto all their diamonds. This essentially means that anyone who buys a DeBeers natural diamond will be paying a premium for... a corporate logo.
DeBeers is aparently trying to become Nike.
I.V.
"These laws they're passing won't even compile anymore, let alone execute." - anon