Why Water-ice Doesn't Fully Conform To Third Law Of Thermodynamics

[n2doc]

Meta-materials Mimic Ice And Illuminate Why Water-ice Doesn't Fully Conform To Third Law Of Thermodynamics

ScienceDaily (Aug. 8, 2008) — "Ye canna change the laws of physics!" Scotty warned Captain Kirk on "Star Trek." But engineers and physicists at the University of Maryland may rewrite one of them.

The Third Law of Thermodynamics is on the minds of John Cumings, assistant professor of materials science and engineering at the University of Maryland's A. James Clark School of Engineering, and his research group as they examine the crystal lattice structure of ice and seek to define exactly what happens when it freezes.

"Developing an accurate model of ice would help architects, civil engineers, and environmental engineers understand what happens to structures and systems exposed to freezing conditions," Cumings said. "It could also help us understand and better predict the movement of glaciers."

Understanding the freezing process is not as straightforward as it may seem. The team had to develop a type of pseudo-ice, rather than using real ice, in order to do it.

Despite being one of the most abundant materials on Earth, water, particularly how it freezes, is not completely understood. Most people learn that as temperatures fall, water molecules move more slowly, and that at temperatures below 32º F/0º C, they lock into position, creating a solid—ice. What's going on at a molecular level, says Cumings, is far more complicated and problematic. For one thing, it seems to be in conflict with a fundamental law of physics.

more:
http://www.sciencedaily.com/releases/2008/08/080807144311.htm

(a) A TEM image of the artificial spin ice created by the Cumings group. (b) a close-up image of a small region of the artificial spin ice. Each link is only 500 nm in length. (c) A Lorentz TEM image of the same region as (b). Here the magnetic direction can be determined by the bright and dark lines in each link. Despite showing disordered configurations, each vertex obeys the ice rule. (Credit: Cumings research group, U-MD)

[The Velveteen Ocelot]

1. Uh oh. Are these guys trying to invent Ice-9?

[eppur_se_muova]

2. My first guess would be a barrier of activation ...

"Over extremely long periods of time and at extremely low temperatures, however, ice may fully order itself, but this is something scientists have yet to prove."

Maybe not that big a mystery?

[Duppers]

3. Such a 'violation' is not a firm conclusion

This article says:
"Materials that violated the Third Law as originally written were found in the 1930s, mainly non-crystalline substances such as glasses and polymers. The Third Law was rewritten to say that all pure crystalline materials' entropy moves toward zero as their temperatures move toward absolute zero. Ice is crystalline—but it seems only its oxygen atoms obey the Law.
Over extremely long periods of time and at extremely low temperatures, however, ice may fully order itself, but this is something scientists have yet to prove."

"Ice has more phrases than any other material I can think of. I don't know that what they're seeing is not just multi-phases." - PhD Materials Physicist, NASA Langley Research Center. "Consider another material, for instance: glass is a anamorphic fluid that flows over a period of time."

Time and temperature are the factors not fully considered here; therefore, one cannot conclude with any certainty that the Third Law Of Thermodynamics has been violated.

[Odin2005]

5. Ice is really interesting stuff.

Doesn't ice have something like 12 different crystal configurations it can be in depending on temperature and pressure?

[Odin2005]

4. This is really cool stuff.

I like how they use substances that can be made to act like giant atoms so they can observe this stuff this an electron microscope!

"Artificial spin ice is a collection of "pseudo-atoms" made of a nickel-iron alloy. Each pseudo-atom is a large-scale model made out of millions of atoms whose collective behavior mimics that of a single one."

The ultimate impact of the research may go beyond civil engineering and the environment. "Although we're mimicking the behavior of ice," Cumings explained, "our meta-material is very similar to patterned hard-disk media. Magnetic 'bits' used in hard drives are usually placed at random, but memory density could be increased if they were in a tight, regular pattern instead.

"We've found that both hydrogen in ice and the pseudo-hydrogen in our artificial spin ice also behave as bits, can carry information, and interact with each other. Perhaps in the future, engineers will be inspired by this in their hard drive designs. The formal patterning and bit interactions may actually help to stabilize information, ultimately leading to drives with much higher capacities."

This is sweet stuff!