The Crystal Structure of Magnesium Di-Zincide

Crystals of the intermetallic compound, Mg${\mathrm{Zn}}_2$, 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 $a=5.15\mathrm{}\mathrm{A}$ and $c=8.48\mathrm{}\mathrm{A}$. 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: $\mathrm{Zn}:u, \overline{u}, \frac{1}{4}; 2\overline{u}, \overline{u}, \frac{1}{4}; u, 2u, \frac{1}{4}; \overline{u}, u, \frac{3}{4}; 2u, u, \frac{3}{4}; \overline{u}, 2\overline{u}, \frac{3}{4}; 0, 0, 0; 0, 0, \frac{1}{2}$ $\mathrm{Mg}:\frac{1}{3}, \frac{2}{3}, v; \frac{1}{3}, \frac{2}{3}, \frac{1}{2}-v; \frac{2}{3}, \frac{1}{3}, \frac{1}{2}+v; \frac{2}{3}, \frac{1}{3}, \overline{v}.$ Where $u=0.830\mathrm{}$ and $v=0.062\mathrm{}$. 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.