Electronic structure of the ternary Zintl-phase compounds Zr3Ni3Sb4, Hf3Ni3Sb4, and Zr3Pt3Sb4 and their similarity to half-Heusler compounds such as ZrNiSn

The Zintl-phase compounds Zr3Ni3Sb4, Hf3Ni3Sb4, and Zr3Pt3Sb4, are the first compounds discovered in this crystal structure not to contain Y or an f-electron atom. We have attempted to understand their electronic structure by comparison to the more extensively studied half-Heusler compounds such as ZrNiSn. While the half-Heusler compounds have more ionic bonding in its stuffed-NaCl crystal structure compared to the covalent Zintl network, several similarities were found between the calculated electronic structures. These similarities include the nature of the bonding, the formation of the ternary compound by adding Ni (or Pt) atoms into the octahedrally coordinated pockets of a known binary compound, and the gap formation due to Ni (or Pt) d-Zr d hybridization.