Structural versatility of the ε-SmGa_x Phase: X-Ray, electron diffraction, and DFT studies

Two new compounds, SmGa_2.67 (hexagonal, P62c, Z ) 15, a ) 12.861(2), c ) 8.4402(8) Å) and SmGa3.64 (orthorhombic, Fmmm, Z ) 24, a ) 8.493(1), b ) 14.912(2), c ) 17.080(2) Å), have been synthesized and identified in the Sm-Ga system and their crystal structures solved and refined from single-crystal X-ray diffraction. These structures display consistent atomic disorder. Electronic structures have been calculated using first-principle DFT methods with ordered models. Atomic arrangements and bonding are analyzed on the basis of gallium partial anionic networks; they are compared with those of some analogous compounds in the other lanthanide-gallium systems.