Crystal structure and physical properties of new ternary gallides Eu 2Rh3Ga9 and Eu2Ir3Ga 9

Abstract

The compounds Eu2Rh3Ga9 and Eu 2Ir3Ga9 were synthesized by melting the elements in sealed tantalum tubes with subsequent annealing at 600 ̊C. Both gallides are isotypic with Y2Co3Ga9 (space group Cmcm, Pearson symbol oC56, Z = 4) as evidenced by single crystal structure analysis: a = 12.9902(6), b = 7.6141(4), c = 9.7433(5) Å, RF = 0.025, 617 structure factors, 42 variable parameters for Eu2Rh 3Ga9, and a = 13.0371(7), b = 7.6017(4), c = 9.6972(6) Å, RF = 0.032, 645 reflections, 42 variables for Eu 2Ir3Ga9. Magnetic susceptibility measurements as well as X-ray absorption spectra indicate the 4f7 electronic configuration of europium (Eu2+) with significant admixture of the 4f6 state in both compounds. © 2006 Verlag der Zeitschrift für Naturforschung.