Zr₇Sb₄: A New Binary Zirconium-Rich Antimonide

Zr7Sb4 has been prepared by arc-melting of the elemental components and annealing at 1000−1150 °C. Its crystal structure was determined by X-ray diffraction (Pearson symbol mP44, monoclinic, space group P21/c, Z = 4, a = 8.4905(6) Å, b = 11.1557(8) Å, c = 11.1217(8) Å, β = 111.443(2)° at 295 K). Zr7Sb4 is isotypic to Hf6TiSb4, a compound stabilized by differential fractional site occupancy. It is the first binary group-4 antimonide with this metal-to-antimony ratio, but it differs from the corresponding phosphides and arsenides M7Pn4 (M = Ti, Zr, Hf; Pn = P, As), which adopt the Nb7P4-type structure. Zr7Sb4 is built up from layers excised from the tetragonal W5Si3-type structure; these layers are displaced relative to each other to maximize interlayer Zr−Zr and Zr−Sb bonding, as confirmed by band structure calculations.