BaAl4-type structure derivatives in the Ga-rich part of the Y–Cu–Ga system

The crystal structures of seven Ga-rich compounds that exist in the Y–Cu–Ga system were studied by the X-ray single-crystal and powder diffraction methods. The crystal structures of six phases were shown to be constructed from the orthorhombic distorted BaAl4-like fragments by multiplication of its a and b lattice constants. These compounds are: 1-Y1.02Cu1.35Ga2.63 (modified BaAl4-type structure, 1 × 1 multiplication), 2-Y1.04Cu1.12Ga2.84 and 3-Y1.05Cu1.00Ga2.95 (own type structure, 3 × 3), 4-Y1.08Cu0.72Ga3.20 (own, 9 × 9), 5-Y3Cu4Ga7 and 6-Y3.21Cu3.09Ga7.70 (La3Al11, 3 × 1), 7-YCuGa2 (own, 3 × 3).

► We study the crystal structure of Ga-rich compounds in the Y–Cu–Ga system at 500 °C.
► Increasing of Ga-content leads to shift of composition to the higher Y concentration.
► We analyze the behavior of atomic vacancies in the Cu/Ga positions.
► Crystal structure of studied compounds is constructed from the BaAl4-like fragments.