Synthesis, Structure, and Magnetic Properties of the Silicides REIrSi (RE = Ce, Pr, Er, Tm, Lu) and SmIr0.266(8)Si1.734(8)

Abstract

The equiatomic rare earth metal–iridium–silicides REIrSi (RE=Ce, Pr, Er, Tm, Lu) were prepared by arc-melting of the elements and subsequent annealing. All silicides were characterized through their X-ray powder patterns. The structures of CeIrSi, ErIrSi, and LuIrSi were refined from X-ray single crystal diffractometer data: LaIrSi type, P213, a=629.15(2) pm, wR2=0.1232, 280 F2 values, and 11 variable parameters for CeIrSi; TiNiSi type, Pnma, a=673.4(1), b=416.07(5), c=744.88(9) pm, wR2=0.0705, 339 F2 values, and 20 variable parameters for ErIrSi, and a=664.0(3), b=412.9(1), c=742.6(1) pm, wR2=0.0398, 496 F2 values, and 20 variable parameters for LuIrSi. The iridium and silicon atoms in CeIrSi, ErIrSi, and LuIrSi build three-dimensional [IrSi] networks where the iridium atoms have three (CeIrSi, Ir–Si 229 pm) and four (ErIrSi, Ir–Si 247–258 pm; LuIrSi, Ir–Si 245–256 pm) silicon neighbors. The [IrSi] networks leave larger channels in which the cerium, erbium, and lutetium atoms are located. Temperature dependent susceptibility data for LuIrSi indicate Pauli paramagnetism. CeIrSi shows Curie-Weiss paramagnetism above 100 K with an experimental magnetic moment of 2.56(2) μB/Ce atom. With samarium as rare earth metal component the silicide SmIr0.266(8)Si1.734(8) with α-ThSi2 type structure was obtained: I41/amd, a=409.3(1), c=1397.2(5) pm, wR2=0.0575, 161 F2 values, and 9 variable parameters. Within the three-dimensional [Ir0.266Si1.734] network the Ir/Si–Ir/Si distances range from 230 to 237 pm.