Structures and Physical Properties of Rare-Earth Chromium Germanides RECrGe3 (RE = La−Nd, Sm)

The ternary rare-earth chromium germanides RECrGe3 (RE = La−Nd, Sm) have been synthesized by direct reactions of the elements in the presence of Sn flux, or by arc-melting and annealing at 800 °C. Their structures were determined by single-crystal and powder X-ray diffraction. They adopt a hexagonal perovskite structure type (P63/mmc, Z = 2; a = 6.2004(1)−6.0812(3) A, c = 5.7660(6)−5.6594(3) A for RE = La−Sm), unusual for an intermetallic compound, in which chains of face-sharing Cr-centered octahedra are linked by triangular Ge3 clusters. Electrical resistivity measurements show metallic behavior for all RE members, with prominent transitions that coincide closely with ferromagnetic transitions (Tc ranging from 60 to 155 K) seen in the magnetic susceptibility curves. Band structure calculations on LaCrGe3 show the presence of a narrow, partially filled band with high DOS at the Fermi level.