Li(14.7)Mg(36.8)Cu(21.5)Ga(66): an intermetallic representative of a type IV clathrate

Synthetic explorations in the quaternary Li-Mg-Cu-Ga system yield the novel intermetallic Li(14.7(8))Mg(36.8(13))Cu(21.5(5))Ga(66) P6m2, Z = 1, a = 14.0803(4) A, c = 13.6252 (8) A] from within a limited composition range. This contains a unique three-dimensional anionic framework consisting of distinct interbonded Ga(12) icosahedra, dimerized Li@(Cu,Mg)(10)Ga(6) icosioctahedra, and 15-vertex Li@(Cu,Mg)(9)Ga(6) and Li@Cu(3)Ga(12) polyhedra. These polyhedral clusters are hosted by M(20) (5(12)), M(24) (5(12)6(2)), and M(26) (5(12)6(3)) (M = Li/Mg) cages, respectively. The geometries and arrangements of these cages follow those in known type IV clathrate hydrates.