BaMg₄Si₃ structure

Barium Magnesium Silicon

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Showing a subset of atoms around one unit cell at their ionic radii (Mg²⁺, 4 coord = 0.71 A, Ba²⁺, 8 coord = 1.56A, Si^4- (estimated from this structure) = 2.07 A).

Hiding atoms not in the subset of atoms described above

Showing subset atoms at smaller size

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Each Barium is coordinated by 8 Silicon atoms (r=3.49 A). Note the Silicon atoms are arranged in pairs with close contacts (r=2.46 Å) between atoms. These pairs of silicon atoms can be considered to be Si₂^6- ions with a single bond between the silicon atoms.

Each Magnesium is coordinated by 4 Silicon atoms (r=2.76 to 2.79 A).

The Silicon atoms that are part of the Si₂^6- ions are 9 coordinate, with 4 close contacts with Barium and 4 close contacts with Magnesium and one close contact with the other Silicon atom of the Si₂^6- ion.

Each unit cell also contains one Silicide(4-) anion that is coordinated to 8 Magnesium cations.

 Thanks to Tim Duncan and Anita Kohli for help in constructing this page

Na Cl