The Structure of the Y-Phase in the Mg-Ni-Sn System

BOUDARD, MICHEL; BORDET, P.; VINCENT, H.; AUDEBERT, FERNANDO

JOURNAL OF ALLOYS AND COMPOUNDS

Elsevier

Año: 2004 vol. 372 p. 121 - 128

0925-8388

The structure of the Y-phase in the Mg–Ni–Sn system with Mg74.5Ni14.5Sn11 composition was solved by applying the direct methods refined by a standard least square procedure. The space group is N 101 (P42 cm) and the magnitude of the cell parameters are a = b = 9.851(2)Å and c = 6.868(2) Å. The final reliability factor is R = 0.04 for 1575 independent reflections. The structure can be described in terms of an ideal structure containing two chains of cubes of Mg aligned along the c-direction. In each chain, Sn (resp. Ni) atoms occupy different opposite faces for adjacent cubes forming a stacking of tetrahedra along the c-direction. An alternative description in terms of two distorted polyhedral units is also given and the structure is compared with related inter-metallic compounds.