The Crystal Structure of $\mathrm{Zn}_3 \mathrm{As}_2$

In the course of trying to produce doped semiconductors, the Colton lab happened upon a sample of ZnO that had been doped with $\mathrm{Zn}_3 \mathrm{As}_2$. In the difficulty to reproduce such a sample, they became interested in studying $\mathrm{Zn}_3 \mathrm{As}_2$ itself, as the literature disagrees on what the structure is. It is likely that $\mathrm{Zn}_3 \mathrm{As}_2$ has a structure isomorphic to $\mathrm{Cd}_3 \mathrm{As}_2$ due to their number of valence electrons. It is generally agreed upon that these isomorphic structures are a 2x2x4 super structure of anti-fluorite with a 25\% cation deficiency. In this work, two different purity samples of $\mathrm{Zn}_3 \mathrm{As}_2$ are studied and compared to several candidate structures obtained from the literature and additional symmetry arguments. The method of studying the crystalline structure is X-ray diffraction (XRD). The structure was solved using single crystal (SC) XRD, and is presented in this work. The structure found using SC-XRD is also compared to powder XRD data.