CeRh2Al10 - The first rhodium aluminide with a new structure type in the 1:2:10 stoichiometry family

A new member of the RET2Al10 family was synthesized and its crystal structure was determined from single crystal X-ray diffraction. The first aluminide with rhodium adopts a new structure type of 1:2:10 stoichiometry. CeRh2Al10 crystallizes in the tetragonal space group I41/amd with cell parameters a = 8.9284(11) Å and c = 21.769(3) Å and is a substitution variant of CePd3Al9 compound. The mutual arrangement of Rh and Al neighbors within the 20-vertex Ce polyhedron differs in comparison with that of the CeRu2Al10 structure. This leads to the different packing of Ce polyhedra in the unit cell. In CeRh2Al10, zig-zag chains of the shortest CeCe contacts extend in the two mutually perpendicular directions - along the a-axis and along the b-axis. In contrast, in CeRu2Al10, zig-zag chains of the shortest CeCe contacts run in one direction - along the c-axis. We illustrate using key physical properties how the variation in crystal structure produces physical properties in CeRh2Al10 that differ strikingly from the situation in CeRu2Al10.