Single crystal study of the high-Curie-temperature ferromagnet Gd1.02Sc0.98Ge and of Gd2.38Sc2.62Ge3

The title ternary compounds have been thoroughly studied by X-ray diffraction, both on powders and single crystals. The already reported GdScGe does not form exactly at the equiatomic composition but with a stoichiometry slightly richer in Gd: Gd1.02Sc0.98Ge; it crystallizes with the tetragonal CeScSi-type (ordered La2Sb-type, space group 14/mmm) with a=4.261 (1) and c=15.593(5) Angstrom Gd2.38Sc2.62Ge3 is hexagonal, Mn5Si3-type (space group P6(3)/mcm), with cell parameters a=8.276(5) and c=6.116(6) Angstrom. Magnetic measurements show that Gd1.02Sc0.98Ge undergoes a ferromagnetic transition at T-c=350 K, whilst no evidence of long range magnetic ordering has been detected for Gd2.38Sc2.62Ge, from 1.5 to 60 K, as deduced by preliminary heat capacity data. (C) 2002 Elsevier Science BY All rights reserved.