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

The ternary rare-earth chromium germanides RECrGe 3 (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 ( P 6 3 / mmc, Z = 2; a = 6.2004(1)−6.0812(3) Å, c = 5.7660(6)−5.6594(3) Å for RE = La−Sm), unusual for an intermetallic compound, in which chains of face-sharing Cr-centered octahedra are linked by triangular Ge 3 clusters. Electrical resistivity measurements show metallic behavior for all RE members, with prominent transitions that coincide closely with ferromagnetic transitions ( T c ranging from 60 to 155 K) seen in the magnetic susceptibility curves. Band structure calculations on LaCrGe 3 show the presence of a narrow, partially filled band with high DOS at the Fermi level.