Unusually Short Ce–Ru Distances in CeRuAl and Related Compounds

Abstract

The aluminide CeRuAl with orthorhombic LaNiAl-type structure contains two crystallographically independent cerium sites which both exhibit relatively short Ce-Ru distances, i. e. 280 - 302 pm for Ce1 and 286 - 310 pm for Ce2. Susceptibility measurements show intermediate valence behavior of the cerium atoms (1.19(1) μ B per formula unit) and no magnetic ordering down to 2 K. Chemical bonding analysis reveals a non-magnetic ground state and strong Ce-Ru bonding. The Ce-Ru bonding peculiarities of CeRuAl are discussed in line with those of other binary and ternary cerium- ruthenium compounds