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AuNi 3 Si 6 and Au 2 Ni 4 Si 7 : Two New Structure Types Related to the CaF 2 ‐Type Structure
Author(s) -
Stacher Matthias,
Effenberger Herta S.,
Ipser Herbert,
Richter Klaus W.
Publication year - 2015
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201500109
Subject(s) - crystallography , crystal structure , annealing (glass) , homogeneity (statistics) , materials science , diffraction , space group , single crystal , x ray crystallography , chemistry , metallurgy , physics , mathematics , optics , statistics
The two compounds AuNi 3 Si 6 and Au 2 Ni 4 Si 7 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; AuNi 3 Si 6 (Pearson symbol hR 30, space group R $\bar{3}$ m ) and Au 2 Ni 4 Si 7 (Pearson symbol mC 26, space group C 2/ m ). The new crystal structures are related to that of NiSi 2 (CaF 2 ‐type); AuNi 3 Si 6 may be derived from this structure by a shear operation, while Au 2 Ni 4 Si 7 may be regarded as intergrowth structure of the CaF 2 and Hg 2 Pt‐type.