AuNi3Si6 and Au2Ni4Si7: Two New Structure Types Related to the CaF2‐Type Structure

Abstract

AbstractThe two compounds AuNi3Si6 and Au2Ni4Si7 were prepared from the elements by arc melting and subsequent annealing at 500 °C. They were investigated by X‐ray diffraction (powder and single‐crystal methods) and by scanning‐electron microscopy which was used for the independent determination of the phase compositions. Both compounds show only minor homogeneity ranges. Single‐crystal XRD was used for structure determination. Both title compounds crystallize in new structure types; AuNi3Si6 (Pearson symbol hR30, space group R$\bar{3}$m) and Au2Ni4Si7 (Pearson symbol mC26, space group C2/m). The new crystal structures are related to that of NiSi2 (CaF2‐type); AuNi3Si6 may be derived from this structure by a shear operation, while Au2Ni4Si7 may be regarded as intergrowth structure of the CaF2 and Hg2Pt‐type.