First-ever solid-state iron-bismuth compound created | October 31, 2016 Issue - Vol. 94 Issue 43 | Chemical & Engineering News
Volume 94 Issue 43 | p. 6 | News of The Week
Issue Date: October 31, 2016 | Web Date: October 28, 2016

First-ever solid-state iron-bismuth compound created

Elusive species completes iron pnictide series
Department: Science & Technology
News Channels: Materials SCENE
Keywords: Inorganic chemistry, materials, pnictide, superconductor, magnetic
FeBi2 is the first solid-state material reported with iron-bismuth bonds (Fe is red, Bi is purple).
Credit: ACS Cent. Sci.
Structure of iron-bismuth complex.
FeBi2 is the first solid-state material reported with iron-bismuth bonds (Fe is red, Bi is purple).
Credit: ACS Cent. Sci.

The first-ever solid-state material reported to contain iron-bismuth bonds, FeBi2, has been prepared by a team led by Danna E. Freedman of Northwestern University (ACS Cent. Sci. 2016, DOI: 10.1021/acscentsci.6b00287).

Iron and bismuth each react with multiple elements across the periodic table but are largely immiscible with each other, despite the fact that iron readily combines with all of the other group 15 elements to form superconducting materials. Chemists currently don’t understand the lack of reactivity between iron and bismuth.

Freedman and colleagues created FeBi2 by combining the two elements in a diamond anvil cell at 30 gigapascals and 1,500 K. In the crystal structure, each iron atom is coordinated by eight bismuth atoms arranged into squares above and below the iron. The squares of bismuth atoms sit twisted relative to each other.

The high pressure stabilizes the Fe–Bi bonds in the material, which is also held together by Bi–Bi bonds. The Fe–Bi bond lengths are 0.2719 nm, while the Bi–Bi interactions range from 0.2948 to 0.3419 nm.

The researchers were able to decompress the FeBi2 down to 3 GPa before it decomposed. That behavior suggests that there might be a way to quickly cool and slowly decompress the material to study and perhaps even use it at ambient pressure—0.0001 GPa—and low temperature, the researchers say.

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Luis (October 28, 2016 11:25 PM)
Great. And what about it's properties? I know it's so early for this, but I hope you publish information about this compound in a near future.
Abbas (October 29, 2016 3:09 PM)
Nice informations
Bryce Carson (October 29, 2016 9:19 PM)
Did the researches note any magnetic properties before decomposition?
John Bevis (October 30, 2016 11:40 AM)
I'm having a hard time with the FeBi2 bonds. Isn't it FeBi8 because each Fe atom is bonded to 8 Bi atoms in the molecular models.
Jyllian (October 30, 2016 10:26 PM)
If you look at the right-side image that shows more repeats of the crystal structure, you'll see that each Bi is bound to two Fe. The overall stoichiometric ratio is FeBi2.
Jin (November 2, 2016 4:07 PM)
By looking at the two images, each Fe is bonded to 8 Bi and each Bi is bonded to four Fe, which makes the overall ratio of FeBi2.
Jyllian (November 6, 2016 10:56 PM)
Whoops, right, each Bi is bound to four Fe.
Vladimir Nalbandyan (November 2, 2016 4:26 PM)
The last comment means that 2*2=8. If Fe:Bi ratio is 1:2, and each Fe is surrounded by 8 Bi, then there should be (on average) 4Fe contacting each Bi. It seems to be the CuAl2 (or BFe2) structure type.

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