Novel Zn9-cluster compounds RE2Zn6Ge3 (RE: La, Ce, Pr, Nd, Sm, Gd):: crystal structure and physical properties

A novel ternary structure type has been determined from single crystals of Ce2Zn6Ge3 grown from indium-zinc flux solvent. The Ce2Zn6Ge3 type is hexagonal (a = 0.767 69(2) nm; c = 0.41159(2) nm) with space group P62m, Z = 1. Isotypic compounds with La, Pr, Nd, Sm and Gd were synthesized by reaction sintering, and their isotypic crystal. structures were confirmed from Rietveld refinements. These novel temaries show metallic behaviour and their ground state depends on the particular rare earth ion. Long-range magnetic order was deduced for the compounds from Ce to Gd, with a maximum transition temperature T-N similar to 29 K for Gd2Zn6Ge3. While the compounds with Ce and Pr exhibit a spontaneous magnetic type of order, those with Nd, Sm and Gd are antiferromagnetic. The magnetic structures of Pr2Zn6Ge3 and Nd2Zn6Ge3 were resolved on the basis of neutron powder diffraction performed at 1.5 K.