Structural and magnetic properties of the Mn5Si3-type (Gd1-xScx)5Ge3 compounds

The series of pseudo-binary compounds (Gd1-xScx)Ge-3, with x=0, 0.1, 0.3, 0.4, 0.52, 1, has been thoroughly studied by X-ray diffraction, both on powders and single crystals. All phases are isotypic, crystallizing with the Mn5Si3 structure type, and the occurrence of a complete solid solution has been shown. The two Mn sites of the hexagonal lattice, i.e. the 4d and 6g positions, are preferentially occupied by Sc and Gd atoms, respectively. Magnetisation measurements show that Sc5Ge3 is a Pauli paramagnet while Gd5Ge3 orders antiferromagnetically at 80 K. The magnetic behaviour is appreciably affected with the replacement of Gd by Sc and even for x=0.1 there is no distinct signature of antiferromagnetic transition. At higher x, spin glass-like ordering is indicated by broad peaks in the magnetisation around 20 K with no corresponding anomaly in the heat capacity data. (C) 2002 Elsevier Science B.V. All rights reserved.