Novel ternary compound Ce2RuAl: Synthesis, crystal structure, magnetic and electrical properties

• The aluminide Ce2RuAl crystallizes in a new structural type related with LaF3.
• Some Ce–Ru distances in the unit cell are unusually short (2.4821(6) Å).
• The average valence of cerium in Ce2RuAl is higher than 3.
• Intermediate-valence in Ce2RuAl was proven by physical property measurements.

The intermetallic phase Ce2RuAl was synthesized by arc melting the elemental components and subsequent annealing of the product at 823 K. Its crystal structure was determined from the single-crystal X-ray diffraction data and confirmed by powder X-ray diffraction at room temperature. The compound is of a new structural type related to the LaF3-type of structure: space group P63cm, Z = 6, a = 7.8362(7) Å, c = 9.7510(9) Å, Pearson symbol hP24. Some Ce–Ru distances in the unit cell are unusually short being equal to 2.4821(6) Å. This structural feature brings about instability in the cerium valence state, directly evidenced in the XANES data and corroborated in the study of bulk physical behavior in Ce2RuAl.