Crystallography365

Blogging a crystal structure a day in 2014

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Helen Maynard-Casely

Another strange element – β Uranium

What does it look like?

Image generated by the VESTA (Visualisation for Electronic and STructual analysis) software http://jp-minerals.org/vesta/en/

Image generated by the VESTA (Visualisation for Electronic and STructural analysis) software http://jp-minerals.org/vesta/en/

What is it?

Uranium is a complicated element as it is, but like carbon is can also form in a number of crystal structures – three have been identified to date, known as α, β and γ forms. The α and γ structures were found to be relatively simple, that is with only a few atoms in each repeating unit of the structure. However, that wasn't the case for β Uranium. It's a very complicated structure, with 30 atoms in the basic unit cell needed to build the whole structure. At the time it was discovered, in 1951, it was thought that this structure was the same as that being discovered in some metal alloys, known as 'σ-phases'. Though this was found not to be the case, this structure has still left many puzzling why elements (where the atoms should all be identical) would form such elaborate structures.

Where did the structure come from?

The image of the crystal structure was built from information in the paper by Tucker and Senio in 1953, which was an improvement on their original structure determination.

Tags: complex   uranium   elements   historic