Preparation and Structures of Lanthanoid Germanides, PrGe3.36, NdGe3.25, and TmGe3 with Double Square Ge-Mesh Structures

Abstract

Abstract A series of lanthanoid trigermanides of Pr, Nd, and Tm has been prepared by high-pressure (3–5 GPa) and high-temperature (1200 °C) reactions. TmGe3 crystallizes in an orthorhombic unit cell (Cmcm, No. 63) with a = 3.990(1) Å, b = 20.488(5) Å, c = 3.8794(8) Å, and V = 317.2(1) Å3. It is isotypic with the DyGe3 structure composed of Ge zig-zag chains and Tm situated between double square Ge-meshes. PrGe3.36 crystallizes in an orthorhombic unit cell (Cmmm, No. 65) with a = 4.062(4) Å, b = 21.43(3) Å, c = 4.212(6) Å, and V = 366.6(8) Å3. The structure is principally the same to the DyGe3 structure but contains an additional Ge site. The site is partially occupied, and is situated on the square mesh. Each Ge atom in the site is coordinated by five Ge atoms in the chain and in the mesh. NdGe3.25 is isotypic with PrGe3.36 and has lattice constants of a = 4.073(1) Å, b = 20.961(6) Å, c = 4.254(1) Å, and V = 363.2(2) Å3. The magnetic susceptibilities of PrGe3.36 and NdGe3.25 follow the Curie–Weiss law with the effective magnetic moments μeff = 3.60 and 3.57 μB, respectively, implying the oxidation states of Pr and Nd are 3+.