New Quaternary Compounds R3MnAl3Ge2 (R - Rare Earth)

Abstract

Nine new quaternaryR3MnAl3Ge2alumogermanides (R= Sm, Gd-Lu) were synthesized by arc melting and their crystal structures were studied by X-ray powder diffraction. All of the compounds crystallize in hexagonal Y3NiAl3Ge2-type structures: Pearson symbolhP9, space groupP-62m. The unit-cell parameters of the isotypic compounds decrease with decreasing radius of the rare-earth metal. The hexagonal structure type Y3NiAl3Ge2(Z= 1) is a quaternary ordering variant of the binary type Fe2P (Z= 3) and the ternary types β1-K2UF6, Lu3CoGa5, Zr3Cu4Si2(Z= 1), ZrNiAl (Z= 3). It belongs to the family of structures with trigonal prismatic coordination of the small atoms.