New MgAgAs-, LiGaGe-, and TiNiSi-structure phases containing d- and p-elements

The ternary phases ZrCuSn and HfCuSn and quaternary phases derived from MNiSn (M = Zr, Hf) by replacing one of the constituent elements with two elements from neighboring groups in the Periodic Table were prepared by are-melting, and their structure and physical properties were studied. The compounds Sc0.5Nb0.5NiSn, ZrNiIn0.5Sb0.5, and HfNiIn0.5Sb0.5 crystallize in the MgAgAs structure (sp. gr. F (4) over bar 3m); ZrCo0.5Cu0.5Sn, HfCo0.5Cu0.5Sn, and HfCuSn crystallize in the LiGaCe structure (sp, gr. P6(3)mc); and ZrCuSn has a TiNiSi-type structure (sp. gr. Pnma). All of the phases studied possess metallic properties, except for the stannide Sc0.5Nb0.5NiSn, which shows semiconductor-like behavior. Structural data and electrical measurements highlight the important part that the number of valence electrons per unit cell plays in the formation of MgAgAs-structure compounds.