Rare earth metal-rich indides RE 4IrIn (RE = Gd–Er), RE 4IrInO0.25 (RE = Gd, Er), and RE 4 TIn1–x Mg x (RE = Y, Gd; T = Rh, Ir)

Abstract

The rare earth-transition metal-indides RE4IrIn (RE = Gd–Er) and the solid solutions RE4TIn1–xMgx (RE = Y, Gd; T = Rh, Ir) were prepared by arc-melting of the elements and subsequent annealing. The rare earth sesquioxides were used as oxygen source for the suboxides RE4IrInO0.25 (RE = Gd, Er). Single crystals of the indides were grown via slowly cooling of the samples and they were investigated via X-ray powder diffraction and single crystal diffractometer data: Gd4RhIn type, F\(\bar 4\)3m, a = 1372.3(6) pm for Gd4IrIn, a = 1365.3(6) pm for Tb4IrIn, a = 1356.7(4) pm for Dy4IrIn, a = 1353.9(4) pm for Ho4IrIn, a = 1344.1(4) pm for Er4IrIn, a = 1370.3(5) pm for Y4RhIn0.54Mg0.46, a = 1375.6(5) pm for Gd4IrIn0.55Mg0.45, a = 1373.0(3) pm for Gd4IrInO0.25, and a = 1345.1(4) pm for Er4IrInO0.25. The rhodium and iridium atoms have a trigonal prismatic rare earth coordination. Condensation of the RhRE6 and IrRE6 prisms leads to three-dimensional networks which leave voids that are filled by regular In4 or mixed In4–xMgx tetrahedra. The indium (magnesium) atoms have twelve nearest neighbors (3In(Mg) + 9RE) in icosahedral coordination. The rare earth atoms build up a three-dimensional, adamantane-like network of condensed, edge and face-sharing octahedra. For Gd4IrInO0.25 and Er4IrInO0.25 the RE16 octahedra are filled with oxygen. The crystal chemical peculiarities of these rare earth rich compounds are discussed.