New metal-rich compounds NbIrSi, NbIrGe, and TaIrSi - Synthesis, structure, and magnetic properties

The metal-rich intermetallic compounds NbIrSi, NbIrGe, and TaIrSi were synt hesized by are-melting of the elements and subsequent annealing in glassy c arbon crucibles in a high-frequency furnace. The three compounds were inves tigated by X ray diffraction on powders and single crystals: TiNiSi type, P nma, a = 641.27(3), b = 379.48(2), c = 727.70(3) pm, wR2 = 0.0773, 430 F-2 values for NbIrSi, a = 645.48(3), b = 389.21(2), c = 741.11(4) pm, wR2 = 0. 0981, 297 F-2 values for NbIrGe, and a = 638.11(3), b = 378.69(2), c = 726. 78 (3) pm, wR2 = 0.0887, 290 F-2 values for TaIrSi with 20 variables for ea ch refinement. The iridium and silicon (germanium) atoms form a three-dimen sional network of puckered Ir3Si3 and Ir3Ge3 hexagons in which the niobium (tantalum) atoms fill larger cages. Magnetic susceptibility measurements on NbIrSi and TaIrSi indicate Pauli paramagnetism with room temperature susce ptibilities of 0.30(5).10(-9) and 0.97(5).10(-9) m(3)/mol, respectively.