1. The nickel arsenide structure can be thought of as a hexagonal close packed array of anions, with all the octahedral interstices filled by cations. Here every anion is surrounded by four cations and has tetrahedral coordination geometry. Similarly, every cation is tetrahedrally coordinated by four anions.
1. The ZincSulphide (Wurtstite) structure can be thought of as a hexagonal close packed array of anions, with all the tetrahedral interstices filled by cations. Here every anion is surrounded by four cations and has tetrahedral coordination geometry. Similarly, every cation is tetrahedrally coordinated by four anions.