STRUCTURE REFINEMENT OF MG2CU AND A COMPARISON OF THE MG2CU, MG2NI AND AL2CU STRUCTURE TYPES

Dimagnesium copper, Mg2CU, M(r) = 11 2.170, orthorhombic, Fddd (70), a = 5.275 (1), b = 9.044 (1), c = 18.328 (2) angstrom, V = 874.3 (2) angstrom3, Z = 16, D(x) = 3.41 g cm -3, Mo Kalpha (lambda = 0.71073 angstrom), mu = 101.145 cm-1, F(000) = 848, T = 293 K, R = 0.034 (wR = 0.031) for 17 refined parameters and 310 observed X-ray single-crystal- reflections [F(o) > 3sigma(F(o))]. The refined parameters are consistent with the nonrefined parameters reported by Schubert & Anderko [Z. Metallkd. (1951), 42, 321-325]. The Mg2Cu structure type can be derived by a stacking of slabs that build up the Al2Cu and Mg2Ni structure types.