Chemistry in Polar Intermetallic Compounds. The Interstitial Chemistry of Zr₅Sn₃

The formation of stoichiometric Zr₅Sn₃Z derivatives through incorporation of Z within chains of confacial zirconium octahedra in the Zr₅Sn₃ (Mn5Si₃-type) parent has been studied principally through reactive powder sintering in the range 1000-1350 °C and by X-ray diffraction means. Examples with Z = B, C, N, O, Al, Si, P, S, Cu, Zn, Ga, Ge, Sn, As, and Se have been quantitatively synthesized and characterized as powders. Complications are noted with arc-melting methods and for Z = Fe, Co, Ni where mixed Z-Sn interstitials occur. Single crystal diffraction for Z = C, O, and Ge and Rietveld powder refinement for Ga demonstrate how the host Zr₆ cavities contract or expand to accommodate Z. The Zr₅Sn₃S_x system at 1050 °C is nonstoichiometric over the range 1 < x < ~0.5. Volume trends as a function of Z follow the metallic/covalent radii of Z well.