Preparation, Crystal Structure and Physical Properties of the Superconducting Ba3Ge16Ir4
The cage compound Ba3Ge16Ir4 crystallizes with the Ba3Ge16Rh4 type of crystal structure, which represents a hierarchical derivative of the BaAl4 type. The crystal structure [Pearson symbol tI46, space group I4/mmm; a = 6.5312(2) Å, c = 22.2845(6) Å] was refined from single-crystal X-ray diffraction data. The phase was obtained after 10 d at 910 °C with small impurities of clathrate-I, BaGe7Ir2 and α-Ge remaining at the grain boundaries. Ba3Ge16Ir4 is a Pauli-paramagnetic metal, which becomes superconducting below Tc = 5.1 K. Electronic structure and analysis of the chemical bonding were performed based on density functional theory calculations. The physical properties are discussed in comparison to the isotypic phase Ba3Ge16Rh4.
Hong Duong Nguyen, Yurii Prots, Walter Schnelle, Bodo Böhme, Michael Baitinger, Silke Paschen, and Yuri Grin, Z. Anorg. Allg. Chem. 2014, 640, (5), 760–767.