Novel intermetallics RE5Ru3Ga2 (RE = La, Ce, Pr, Nd): synthesis and crystal structures; thermodynamic and electrical transport properties of Ce5Ru3Ga2

Abstract Novel ternary gallides RE5Ru3Ga2 (RE = La, Ce, Pr, and Nd) crystallize with a cubic structure of the La5Ru3Al2 type (space group I213) with the lattice parameters: a = 9.9082(3), 9.6926(4), 9.7509(5), and 9.7222(4) A, respectively. Upon small substitution of Al for Ga (≤1 at. % Al), the compound Ce5Ru3Ga2-xAlx can be stabilized as a low-temperature trigonal variant (space group R3). The latter phase, bearing the unit cell parameters a = 13.7892(3) A and c = 8.3095(2) A, is closely related to the Ce5Ru3Al2 structure type. Its characteristic structural feature is the presence of very short interatomic Ce-Ru distances of 2.40(4) A. The cubic Ce5Ru3Ga2 exhibits Curie-Weiss paramagnetism with notably reduced effective magnetic moment. At TC = 1.7 K, the compound orders magnetically, probably with a ferrimagnetic magnetic structure. The metallic-like electrical conductivity of this material bears a Kondo lattice character.