NEW TERNARY INTERMETALLIC COMPOUNDS WITH CLATHRATE STRUCTURE - BA8(T,SI)6SI40 AND BA6(T,GE)6GE40 WHERE T = NI, PD, PT, CU, AG, AU

The isotypic compounds Ba8[(T,Si)6Si40] and Ba6[(T,Ge)6Ge40] (T = Ni, Pd, Pt, Cu, Ag, Au) are cubic (space group Pm3m, Z = 1) with the following lattice constants: Ba8[Ni1.8Si44.2], a = 1028.5(5) pm; Ba8[Pd2.5Si43.5], a = 1034.5(8) pm; Ba8[Pt2.7Si43.3], a = 1035.4(2) pm; Ba8[Cu4.0Si42], a = 1034.4(5) pm; Ba8[Ag3.8Si42.2], a = 1047.8(6) pm; Ba8[Au6Si40], a = 1042.2(2) pm; Ba8[Ni6Ge40], a = 1067.6(5) pm; Ba8[Pd6Ge40], a = 1078.1(1) pm; Ba8[(Pt,Ge)6Ge40], a = 1074.5(l) pm; Ba8[Cu6Ge40], a = 1068.59(8) pm; Ba8[Ag6Ge40], a = 1084.0(1) pm; Ba8[Au6Ge40], a = 1079.87(7) pm. Transition metals together with group IV element atoms are arranged in an [X46] framework of the K8[Si46] structure type.