Novel ternary germanide CeRuGe5: Crystal structure and physical properties

- A novel CeRuGe5 intermetallic crystallizes with a new tetragonal type of structure.
- A CeRuGe5 crystal structure is closely related to HoCoGa5- and Sm2Ru5Ga9-types.
- The Ce ions in CeRuGe5 exhibit a well-defined 4f1 electronic state.
- Down to 1.7 K the compound does not order magnetically.

The new ternary intermetallic with high content of germanium, CeRuGe5, was found in the course of reinvestigation of the Ce-Ru-Ge system at 700 °C. The compound crystallizes in the tetragonal structure of new type (space group I4/mcm) with the unit cell parameters: a = 6.1414(6) Å, c = 13.751(3) Å, Z = 4, Pearson symbol tI28. The structure of CeRuGe5 can be presented as [CeGe3] and [RuGe2] slabs alternating along the tetragonal c-axis. It is shown that the new structure of CeRuGe5 and the known before structure of Sm2Ru5Ga9 are derivatives from the common prototype - HoCoGa5.By means of magnetic, heat capacity and electrical transport measurements, the novel compound CeRuGe5 was established to be a metallic Curie-Weiss paramagnet due to stable 4f1 electronic configuration of trivalent Ce ions. No intrinsic long-range magnetic ordering was found down to 1.7 K.