Intermetallic Phases in the Ca‐Cu‐Sn System

Twelve ternary alloys in the Ca‐Cu‐Sn system were synthesized as a test on the existing phases. They were prepared from the elements sealed under argon in Ta crucibles, melted in an induction furnace and annealed at 700 °C or 600 °C. Four ordered compounds were found: CaCuSn (YbAuSn type), Imm 2, a = 4.597(1) Å, b = 22.027(2) Å, c = 7.939(1) Å, Z = 12, wR2 = 0.080, 1683 F 2 values; Ca 3 Cu 8 Sn 4 (Nd 3 Co 8 Sn 4 type), P 6 3 mc , a = 9.125(1) Å, c = 7.728(1) Å, Z = 2, wR2 = 0.087, 704 F 2 values; CaCu 2 Sn 2 (new structure type), C 2 /m , a = 10.943(3) Å, b = 4.222(1) Å, c = 4.834(1) Å, β = 107.94(1)°, Z = 2, wR2 = 0.051, 343 F 2 values; CaCu 9 Sn 4 (LaFe 9 Si 4 type), I 4 /mcm , a = 8.630(1) Å, c = 12.402(1) Å, Z = 4, wR2 = 0.047, 566 F 2 values. In all phases the shortest Cu‐Sn distances are in the range 2.59‐2.66Å, while the shortest Cu‐Cu distances are practically the same, 2.53‐2.54Å, except CaCuSn where no Cu‐Cu contacts occur.