Ce11Ge3.73(2)In6.27: Solid-state synthesis, crystal structure and site-preference

• Block or short-bar shaped single-crystals of Ce11Ge3.73(2)In6.27 were synthesized.
• The first example of having the In/Ge mixture at the “isolated” anionic site.
• The site-preference of In was rationalized by the site- and bond-energies.

A novel intermetallic compound of Ce11Ge3.73(2)In6.27 has been synthesized through the high-temperature solid-state reaction using Nb-ampoules. A batch of well grown block-/short bar-shaped single-crystals has been obtained, and the crystal structure of the title compound has been characterized by single-crystal X-ray diffraction analyses. Ce11Ge3.73(2)In6.27 adopts the Ho11Ge10-type structure belonging to the tetragonal space group I4/mmm (Z=4, Pearson symbol tI84) with nine crystallographically unique atomic positions in the asymmetric unit. The lattice parameters are a=12.0163(1) Å and c=16.5396(2) Å. The overall crystal structure can simply be depicted as an assembly of three different types of co-facial cationic polyhedra centered by anions, which is further enclosed by the three-dimensional (3-D) cage-like anionic framework. The extra amount of In is observed in one of three isolated anionic sites resulting in introducing the Ge/In-mixed site at the Wyckoff 4e site. This unique site-preference of In substitution for Ge at the 4e site has been enlightened via the atomic size-aspect which was fully supported and rationalized by the site- and bond-energies analyses using tight-binding linear muffin-tin orbital (TB-LMTO) calculations. Energy-dispersive X-ray spectroscopy (EDS), density of states (DOS), crystal orbital Hamilton population (COHP), and electron localization function (ELF) analyses for the title compound are also presented. Magnetic susceptibility measurement proves that an antiferromagnetic ordering of Ce atoms at a low temperature with a paramagnetic Curie temperature of −23.2 K.

Reported is experimental and theoretical investigations for Ce11Ge3.73(2)In6.27, which is the first reported example having the extra amounts of In substitution for Ge at one of three “isolated” anionic sites in the Ho11Ge10-type phase. The observed In site-preference toward the particular anionic site was rationalized via the atomic size-aspect supported by comprehensive analyses for the site-energies including the Wyckoff 4e and 8j sites.Figure optionsDownload as PowerPoint slide