Metal Flux Growth, Structural Relations, and Physical Properties of EuCuGe and EuTIn (T = Cu and Ag).

Single crystals (SCs) of the compounds EuAgIn and EuCuGe were synthesized through the reactions run in liquid indium. EuAgIn crystallizes in the LaAl structure type [orthorhombic space group (SG) Immm] with the lattice parameters: a = 4.8370(1) Å, b = 10.6078(3) Å, and c = 13.9195(4) Å. EuCuGe crystallizes in the tetragonal ThCrSi structure type (SG I4/mmm) with the lattice parameters: a = b = 4.2218(1) Å, and c = 10.3394(5) Å. The crystal structure of EuAgIn is comprised of edge-shared hexagonal rings consisting of indium. The one-dimensional chains of In rings are shared through the edges, which are further interconnected with other six-membered rings forming a three-dimensional (3D) stable crystal structure along the bc plane. The crystal structure of EuCuGe can be explained as the complex [CuGe] polyanionic network embedded with Eu ions. These polyanionic networks present in the crystal structure of EuCuGe are shared through the edges of the 011 plane containing Cu and Ge atoms, resulting in a 3D network. The structural relationship between EuTIn and EuCuGe has been discussed in detail, and we conclude that EuTIn is the metal deficient variant of EuCuGe. The magnetic susceptibilities of EuTIn (T = Cu and Ag) and EuCuGe were measured between 2 and 300 K. In all cases, magnetic susceptibility data followed Curie-Weiss law above 150 K. Magnetic moment values obtained from the measurements indicate the probable mixed/intermediate valent behavior of the europium atoms, which was further confirmed by X-ray absorption studies and bond distances around the Eu atoms. Electrical resistivity measurements suggest that EuTIn and EuCuGe are metallic in nature.