Breakthrough iron-based superconductors set new performance records

Jan 10, 2013
Brookhaven physicists Weidong Si (left) and Qiang Li look into the vacuum chamber where the new high-field iron-based superconductors are made through a process called pulsed-laser deposition.

(Phys.org)—The road to a sustainably powered future may be paved with superconductors. When chilled to frigid temperatures hundreds of degrees Celsius below zero, these remarkable materials are singularly capable of perfectly conducting electric current. To meet growing global energy demands, the entire energy infrastructure would benefit tremendously from incorporating new electricity generation, storage, and delivery technologies that use superconducting wires. But strict limits on temperature, high manufacturing costs, and the dampening effects of high-magnetic fields currently impede widespread adoption.

Now, a collaboration led by scientists at the U.S. Department of Energy's Brookhaven National Laboratory have created a high performance iron-based superconducting wire that opens new pathways for some of the most essential and energy-intensive technologies in the world. These custom-grown materials carry tremendous current under exceptionally high magnetic fields—an order of magnitude higher than those found in , (MRI) machines, and even . The results— published online January 8 in the journal Nature Communications—demonstrate a unique layered structure that outperforms competing low-temperature superconducting wires while avoiding the high manufacturing costs associated with high-temperature superconductor (HTS) alternatives. 

"With the focused effort of this collaboration, we made a major breakthrough in iron chalcogenide-based superconducting films that not only sets the record for maximum critical current under high magnetic fields, but also raises the operating temperature for the material," said Brookhaven Lab physicist Weidong Si. "That could mean conducting more electricity in a wide range of technologies while potentially using less energy to cool down the superconducting wire."

(cuprate) are a leading candidate for advanced energy applications, but these ceramic-based materials are very brittle and require a complicated and expensive multilayer synthesis process. Beyond that, anisotropies—structural asymmetries that prevent current from flowing evenly in different directions across a material—limit overall efficiency in these compounds.

Iron-based superconductors, however, are mechanically semi-metallic and therefore considerably less fragile. They can also be more easily shaped into the kinds of long wires needed in devices like massive offshore wind turbines, and they exhibit nearly isotropic behavior in magnetic fields, which allows for easier technology integration.

The scientists synthesized this novel film of iron, selenium, and tellurium to push existing performance parameters. In addition to the raw materials being relatively inexpensive, the synthesis process itself can be performed at just half the temperature of cuprate-based HTS alternatives, or approximately 400 degrees Celsius.

The team used a thin film fabrication technique called pulsed-laser deposition, which uses a high-power laser to vaporize materials that are then collected in layers on a substrate. This complex technique is a bit like carefully collecting the gas as it rises above a boiling pot, only with nearly atomic-level precision.

"A key breakthrough here is the discovery that adding layers of cesium-oxide in between the films and substrates dramatically increased the superconductor's critical current density, or maximum electricity load, as well as the critical temperature at which the material becomes superconducting," said Brookhaven Lab physicist Qiang Li, head of the Advanced Energy Materials Group and leader of this study. "That critical temperature threshold rose 30 percent over the same compound made without this layering process—still a very cold -253 degrees Celsius, but it promises significant application potential."

When tested, the critical current density of the new iron-based superconductor reached more than 1 million amperes (amps) per square centimeter, which is several hundred times more than regular copper wires can carry over the same area. Under an intense 30-tesla magnetic field, the film carried a record-high 200,000 amperes per square centimeter. For scale, consider that household circuit breakers usually blow when hitting just 20 amps.

In devices such as MRIs, using electricity to generate powerful magnetic fields is essential, and the magnetic tolerance of the must be high. The thin films in the new study remained functional under that 30-tesla magnetic field, while most hospital MRIs require just 1-3 tesla.

The researchers extended the study to include thin films grown on flexible metallic materials called rolling-assisted biaxial textured substrates, or RABiTS. These substrates, developed in a proprietary process invented by scientists at DOE's Oak Ridge National Laboratory, offered a similar performance with particularly important implications for long-length scaled up production in the future. The scientists also used scanning electron microscopes to probe the structure of the thin films and conducted x-ray diffraction tests at Brookhaven's National Synchrotron Light Source to further characterize the materials.

"We believe both critical current and transition temperatures can be further improved as we fine-tune the structure and chemical composition," Qiang Li said. "The next step is to pinpoint the mechanism behind the findings—the relationship between the structure and properties—which will provide guidance for the discovery of new superconductors with even greater performance."

Explore further: CERN: World-record current in a superconductor

More information: Paper: High current superconductivity in FeSe0.5Te0.5-coated conductors at 30 tesla. Nature Communications. www.nature.com/ncomms/journal/v4/n1/full/ncomms2337.html

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User comments : 13

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hb_
5 / 5 (1) Jan 10, 2013
Not bad! Increasing both the critical field and the current density is not bad at all. They have focused on the right parameters when it comes to superconductors; increasing Tc by a degree or two doesn't help as much as increasing the current carrying capabilities of the material.

Once again, really good work!
casualjoe
not rated yet Jan 10, 2013
the dampening effects of high-magnetic fields currently impede widespread adoption


That is such a well written line, amazing.
antialias_physorg
3 / 5 (3) Jan 10, 2013
Well, the temperature needed may also hinder widespread adoption. That Tc (20K) still means it needs liquid helium - and helium is in short supply/expensive.
Superconucting transmission lines will only really become sensible with a Tc somewhat above the temp of liquid nitrogen (77K)

(There are such materials, but making wires from them is tricky, since - as the article mentions - they are very brittle and also somewhat expensive when compared to iron based ones).

So: Good job - but it's still quite a ways to go.
Ober
not rated yet Jan 10, 2013
@natello that site seems quite pathetic. The kind of site that would have been made in the 90's. Can't help but feel the site and its contents are just pure B.S. I put it in the same category as Rossi and cold fusion.
Caliban
not rated yet Jan 11, 2013
@Ober that doesn't seem at all arbitrary.
johanfprins
1 / 5 (2) Jan 11, 2013
At least they are starting to realize that superconduction has to do with layered structures and electron-orbitals: Not with pair formation of "electrons"!!! But how long will it take for the penny to drop that the BCS-model should be called that BS-model!
Osiris1
not rated yet Jan 11, 2013
Good Tech, but Ce...Cesium, Te..Tellurium, and Se...selenium are all rare in our crust and the main source now is China and one mine in out west that the Chinese want to buy. So this tech is pie in sky until we get a militarily stable and dependable source of supply that will not go away in wartime, suddenly.

We should use this in combo with the other recent advances in heat reflection using magnetic fields in our quest for fusion ignition. New enabling tech like this should be brought to bear ASAP
Caliban
5 / 5 (1) Jan 11, 2013
At least they are starting to realize that superconduction has to do with layered structures and electron-orbitals: Not with pair formation of "electrons"!!! But how long will it take for the penny to drop that the BCS-model should be called that BS-model!


Then what are you waitin' for, johafprins? Go to the VC guys and get yer startup$$$m.

I'm sure that with your advanced and superior understanding of the workings of our universe that you will breakthrough on your very first day in the laboratory, thereby vitiating the need for Physorg to further publish any more such idiotic drivel!

RealScience
not rated yet Jan 11, 2013
@natello - the Joe Eck site shows a magnetic anomaly at room temperature. That is just a tiny step toward showing superconductivity, since there are a variety of other types of magnetic phase transitions that occur over a wide range of temperatures.

A small ring carrying a even a miniscule current round and round at room temperature would convince people. Or levitate something, even a grain-of-salt-sized magnet.
johanfprins
1 / 5 (1) Jan 12, 2013
Then what are you waitin' for, johafprins? Go to the VC guys and get yer startup$$$m.
Over the last 10 years the VC guys went to physics-morons like Brian Pippard, Brian Josephson, etc. for a second opinion and are then advised that I "must be wrong"; without of course objectively explaining why my "wrong" model fits the data on SC; also those that BCS cannot explain.

I'm sure that with your advanced and superior understanding of the workings of our universe that you will breakthrough on your very first day in the laboratory,


If I had the laboratory, equipment and finance I would have already had a prototype SMES on the market that operate at room temperature 5 years ago.
thereby vitiating the need for Physorg to further publish any more such idiotic drivel!


Please be specific: Where have I published drivel on Physorg? If you want to claim that I am, you should be able to point out where I am wrong! There are too many apes like you around in the world!
Caliban
not rated yet Jan 13, 2013
thereby vitiating the need for Physorg to further publish any more such idiotic drivel!


Please be specific: Where have I published drivel on Physorg? If you want to claim that I am, you should be able to point out where I am wrong! There are too many apes like you around in the world!


Has Physorg published your drivel before?

I suppose not, since that would obviously have put your career right over the top, which would mean that you wouldn't need to spread your sour grapes in the comment forum.

I would think that someone of your superior intellect wouldn't waste their time monkeying around here at Physorg.

I suppose we should feel honored?

johanfprins
1 / 5 (1) Jan 14, 2013
Has Physorg published your drivel before?
If they did not publish what I have posted you would not have known about me. So I challenge you again: Where have I posted drivel on physorg?

I would think that someone of your superior intellect wouldn't waste their time monkeying around here at Physorg

You are the one monkeying around on physorg: I am not doing this since I do not post BS like you do on physorg.
Caliban
not rated yet Jan 15, 2013
Has Physorg published your drivel before?
If they did not publish what I have posted you would not have known about me. So I challenge you again: Where have I posted drivel on physorg?

I would think that someone of your superior intellect wouldn't waste their time monkeying around here at Physorg

You are the one monkeying around on physorg: I am not doing this since I do not post BS like you do on physorg.


@Johan,

OK, let me put things straight. "Drivel", in the first instance, referred to any article published here on physorg to which you take exception.

I have never thought of the comment forum as being a "publication", and consider that to be an odd notion on your part, but I suppose I'll get over it.

However, since you thought I was saying that your comments were drivel, I couldn't resist taking advantage of the fact to have a little mean fun, which I oughtn't to have.

And, just for the record: No --YOU'RE a monkey.

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