Zinc-deficiency in intermetallics with the NaZn13 type -: Re-determination of the crystal structure and physical properties of EuZn13-x (x=0.25(1))

Reported are the synthesis from zinc flux, crystal structure re-determination front single-crystal X-ray diffraction, and magnetic properties of EuZn13-x(x=0.25(1)). It crystallizes in the cubic NaZn13 type (Pearson's symbol cF112, space group Fm (3) over barc, No. 226) with unit cell parameter a = 12.1651(17) angstrom, determined at 120 K. The structure has two crystallographically unique zinc sites, one of which is partially occupied. This finding is consistent with previous experimental and theoretical work on related Zn-rich networks that suggests an optimal electron count of 27 electrons per formula unit. Temperature-dependent magnetization measurements confirm that the Eu ions in EuZn12.75(1) are divalent as evidenced from the effective magnetic moment of 7.981 mu(B). (C) 2007 Elsevier B.V. All rights reserved.