Bismuth Flux Growth of CeRh6Ge4 and CeRh2Ge2 Single Crystals

Abstract

Single crystals of the germanides CeRh6Ge4 and CeRh2Ge2 were synthesized from the elements in bismuth fluxes. Polycrystalline samples are available by arc-melting. The structures were refined on the basis of single-crystal X-ray diffractometer data. CeRh6Ge4: LiCo6P4 type, P6m2, a=715.4(2), c=385:5(1) pm, wR2=0.0554, 273 F2 values, 19 variables; CeRh2Ge2: ThCr2Si2 type, I4/mmm, a=415.69(6), c=1048:5(2) pm, wR2=0.0391, 131 F2 values, 9 variables. The rhodium and germanium atoms build three-dimensional, covalently bonded [Rh6Ge4] and [Rh2Ge2] networks with Rh-Ge distances ranging from 246 to 255 pm. The cerium atoms are located in larger cavities within these networks: Ce@Ge6Rh12 in CeRh6Ge4 and Ce@Ge8Rh8 in CeRh2Ge2. Temperature-dependent magnetic susceptibility data of CeRh6Ge4 show Curie-Weiss behavior above 70 K with an experimental magnetic moment of 2:35(1) μB per Ce atom. Low-field measurements are indicative of magnetic ordering below 2:5 K.