Researchers develop algorithm to predict new superhard crystals

Sep 14, 2011
An example of superhard structures of carbon found in the calculations.

(PhysOrg.com) -- Stony Brook University researchers,  Artem R. Oganov, Professor of Geosciences and Physics and Dr. Andriy O. Lyakhov, Research Fellow, have developed an algorithm capable of predicting new superhard materials. The findings of their work have just been published in a paper entitled “Evolutionary search for superhard materials: Methodology and applications to forms of carbon and TiO2,” in the current online edition of Physical Review B.

Superhard , used in many scientific and technological applications (for example as abrasive coatings in cutting and drilling tools), are a relatively small class of compounds. The most famous and widely used of these are diamond and cubic boron nitride. However, both of them are unstable at high temperatures, which limit their applicability. Therefore, the search for new superhard compounds is of great interest. Despite numerous efforts, progress has been slow. “The traditional trial-and-error approach to search for new materials usually involves a lot of pain and little gain,” explained Prof. Oganov.

Dr. Lyakhov and Prof. Oganov propose to use supercomputers in the search for new superhard materials. Scientists developed a special hybrid evolutionary algorithm, and tested it on a few promising systems, such as carbon and carbon nitride (which many scientists believe to be able to surpass the diamond by hardness). The results show the power of this algorithm and confirm that diamond is the hardest form of carbon and, so far, the hardest material. As a byproduct of the calculations, a set of novel superhard carbon structures was obtained – these are only marginally softer than diamond. It was also shown that nitride cannot be harder than diamond.

Another area where the algorithm can be used is the validation of controversial experimental data. Researchers give an example by dethroning TiO2 as the hardest known oxide. The suggestion that a high-pressure form of TiO2 is the hardest oxide was made by Swedish researchers in a highly-cited paper published in 2001 in Nature. However, calculations show that all possible forms of TiO2 are much softer than common corundum, Al2O3, and therefore the experimental data from 2001 has to be reconsidered.  The latest experiments done at Yale University and the University of Tokyo point in the same direction. In the near future, scientists plan to apply their to promising systems, such as boron-carbon-oxygen compounds, to search for new superhard materials.

The value of this work goes well beyond the field of superhard materials. The optimization of hardness is a successful proof-of-principle example, which opens the way for a novel computational technique. “A new era in material design and discovery is about to begin,” said Prof. Oganov. “New materials with desired properties will be routinely discovered using supercomputers, instead of the expensive trial-and-error method that is used today.”

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User comments : 13

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Nanobanano
1.3 / 5 (6) Sep 14, 2011
However, calculations show that all possible forms of TiO2 are much softer than common corundum, Al2O3, and therefore the experimental data from 2001 has to be reconsidered


huh?!?

Since when do computer models and "calculations" hold more weight than experimental evidence?

A real world experiment is invalidated because a computer model doesn't support it?!? REALLY!?!

What the hell is this?

Have these people lost their minds?

Or is this article just that poorly written?
TheGhostofOtto1923
2.7 / 5 (7) Sep 14, 2011
Since when do computer models and "calculations" hold more weight than experimental evidence?

A real world experiment is invalidated because a computer model doesn't support it?!? REALLY!?!
When experiments turn out to be faulty. Does your brain seem to stop at the point where it sees a chance for a dis? Respect scientists - they're smarter than you.
rawa1
3.5 / 5 (6) Sep 14, 2011
Respect scientists - they're smarter than you.


Richard Feynman: "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong".
calculations show that all possible forms of TiO2 are much softer than common corundum, Al2O3, and therefore the experimental data from 2001 has to be reconsidered
Rutile Mohs hardness is 6.25, corundum 9.0 by Wolfram Alpha.

Did I miss something? Every kid knows, the rutile is way softer, than the corundum.
Why not to respect Feynman the scientist, after then?
SincerelyTwo
5 / 5 (1) Sep 14, 2011
Since when do computer models and "calculations" hold more weight than experimental evidence?

A real world experiment is invalidated because a computer model doesn't support it?!? REALLY!?!
When experiments turn out to be faulty. Does your brain seem to stop at the point where it sees a chance for a dis? Respect scientists - they're smarter than you.


Many scientists don't even agree with each other.

Why not respect every argument which presents a valid point.

It's equally valid that this article poorly states the situation as well.

... and so forth.
Husky
not rated yet Sep 14, 2011
lonsdalite anyone?
TheGhostofOtto1923
2.3 / 5 (6) Sep 14, 2011
Richard Feynman: "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong".
And feynman certainly knew that theory proves an invaluable check on experiment and vice versa. They work together. Experiments are often conducted incorrectly and this only realized after comparing the results with theory.

You conduct any experiments lately jigga/alizee/zephir? Cooking word soup doesnt count.
Did I miss something?
Yes.
fmfbrestel
3.7 / 5 (3) Sep 14, 2011
A real world experiment is invalidated because a computer model doesn't support it?!? REALLY!?!

What the hell is this?

Have these people lost their minds?


"The latest experiments done at Yale University and the University of Tokyo point in the same direction."

Which is exactly what they were referring to when they said:

"Another area where the algorithm can be used is the validation of controversial experimental data."

Maybe you should read better.
Deadbolt
3 / 5 (2) Sep 14, 2011
Their algorithm pointed at there being a problem with previous results. Sure enough, another experiment confirmed this.

astro_optics
3 / 5 (2) Sep 15, 2011
it's not a matter of respect...just facts...thank you!
despinos
not rated yet Sep 15, 2011
It's quite funny how from time the "harder than diamond" subject appears in articles here. I see that someone still remembers one of those, lonsdaleite. From wiki:
"[...[ Lonsdaleite is simulated to be 58% harder than diamond on the <100> face and to resist indentation pressures of 152 GPa, whereas diamond would break at 97 GPa.[11] This is still below IIa diamond's <111> tip hardness of 162 GPa."
So maybe diamond is still the hardest material yet?
Isaacsname
not rated yet Sep 15, 2011
It's quite funny how from time the "harder than diamond" subject appears in articles here. I see that someone still remembers one of those, lonsdaleite. From wiki:
"[...[ Lonsdaleite is simulated to be 58% harder than diamond on the <100> face and to resist indentation pressures of 152 GPa, whereas diamond would break at 97 GPa.[11] This is still below IIa diamond's <111> tip hardness of 162 GPa."
So maybe diamond is still the hardest material yet?


Sort of..

http://en.wikiped..._nanorod
El_Nose
5 / 5 (1) Sep 15, 2011
DID NO ONE ACTUALLY READ THE ARTICLE ???

@Nanobanano
Since when do computer models and "calculations" hold more weight than experimental evidence?

A real world experiment is invalidated because a computer model doesn't support it?!? REALLY!?!


the article stated:
However, calculations show that all possible forms of TiO2 are much softer than common corundum, Al2O3, and therefore the experimental data from 2001 has to be reconsidered


and the VERY NEXT SENTENCE STATES:

The latest experiments done at Yale University and the University of Tokyo point in the same direction.


come on now guys --
Caliban
not rated yet Sep 17, 2011

calculations show that all possible forms of TiO2 are much softer than common corundum, Al2O3, and therefore the experimental data from 2001 has to be reconsidered .Rutile Mohs hardness is 6.25, corundum 9.0 by Wolfram Alpha.

Did I miss something? Every kid knows, the rutile is way softer, than the corundum.
Why not to respect Feynman the scientist, after then?


Good point, but the thrust here is that -by their calculations- ALL forms of TiO2 are softer than diamond, not just Rutile. Besides, Rutile is far more useful for its thermal properties than its relative hardness.

Still, you were right on the money with the Feynman quote. Too bad he wasn't around when the Titanic was being designed.