The Crystal Structure of Magnesium Di-Zincide

Crystals of the intermetallic compound, MgZn₂, were prepared and the crystal structure was determined from x-ray data furnished by Laue and rotation photographs. The crystal was found to have hexagonal axes with a=5.15A and c=8.48A. The unit cell contains four molecules. The effect of absorption in the crystal in determining the wave-length giving a maximum intensity of reflection in Laue photographs was used to confirm the dimensions of the unit cell. The atoms have the positions: $Zn:u, ū, 1/4; 2ū, ū, 1/4; u, 2u, 1/4; ū, u, 3/4; 2u, u, 3/4; ū, 2ū, 3/4; 0, 0, 0; 0, 0, 1/2$ $Mg:1/3, 2/3, v; 1/3, 2/3, 1/2{-}v; 2/3, 1/3, 1/2+v; 2/3, 1/3, v̄.$ Where $u=0.830$ and $v=0.062$. The least distance between two magnesium atoms is 3.15A, between two zinc atoms, 2.52A, and between a magnesium and a zinc atom, 3.02A.