HfNixP – Intercalation of Ni into the Three-Dimensional Compound HfP

The new compound HfNi_xP (x = 0.426(1), crystal structure: P6₃/mmc, a = 3.737(1) Å, c = 12.666(2) Å, V = 153.21(7) ų) has been prepared by arc-melting of HfP with nickel and subsequent annealing at 1400°C. Its crystal structure can be considered as a filled HfP structure, with the Ni atoms inserted into the trigonal prismatic voids of the Hf sublattice. Since the neighboring trigonal Hf₆ prisms are centered by P atoms, each of the three rectangular faces of the Hf₆Ni prism is capped with one P atom. Altogether, the structure of HfNi_xP consists of alternating layers of Hf atoms with the packing sequence AABB . One P and the Ni position are situated between the eclipsed Hf layers, whereas the other P site between the A and B layers is surrounded by six Hf atoms in a staggered arrangement. The calculated density of states (Extended Hückel approximation) points to metallic conductivity; threedimensional metallic behavior is assumed because of the Hf–Hf bonding interactions along all three directions.