Structure and magnetic properties of hexagonal perovskite-type rare-earth vanadium germanides REVGe3 (RE = La–Nd)

Abstract

The ternary rare-earth vanadium germanides REVGe₃ (RE = La–Nd) have been synthesized by arc-melting and annealing at 800 °C for 3 weeks. Their crystal structures were determined by powder X-ray diffraction and refined by the Rietveld method. The hexagonal cell parameters are a = 6.2587(3)–6.2145(2) Å and c = 5.6992(3)–5.6403(2) Å in the progression from LaVGe₃ to NdVGe₃. Like the previously known chromium-containing series RECrGe₃, they adopt a hexagonal perovskite-type structure, in which chains of face-sharing VGe₆ octahedra are connected by triangular Ge₃ clusters. Except for Pauli paramagnetic LaVGe₃, magnetic measurements revealed weak antiferromagnetic ordering at low temperatures (T_N = 4–15 K) for the other RE members, in contrast to the ferromagnetic ordering found earlier in RECrGe₃. An investigation of the solid solutions LaV_1−xCr_xGe₃ (0 ≤ x ≤ 1) and LaCr_1−xMn_xGe₃ (0 ≤ x ≤ 0.2) revealed that addition of V or Mn into LaCrGe₃ tends to suppress the ferromagnetic ordering.