Abstract
The series of ternary polar intermetallics Eu(Zn1-xGex)2 (0 < x < 1) has been investigated and characterized by powder and single crystal X-ray diffraction as well as physical property measurements. For 0.50(2) ≤ x ≤ 0.75(2), this series shows a homogeneity width of hexagonal AlB2-type phases (space group P6/mmm, Pearson symbol hP3) with Zn and Ge atoms statistically distributed in the planar polyanionic 63 nets. As the Ge content increases in this range, a decreases from 4.3631(6) � to 4.2358(6) �, while c increases from 4.3014(9) � to 4.5759(9) �, resulting in an increasing c/a ratio. Furthermore, the Zn−Ge bond distance within the hexagonal net drops significantly from 2.5190(3) � to 2.4455(3) �, but the anisotropy of the displacement ellipsoids significantly increases along the c-direction. At low and high values of x, respectively, orthorhombic KHg2-type and trigonal EuGe2-type phases are observed as one of the majority phases in corresponding product mixtures. Temperature-dependent magnetic susceptibility measurements for two AlB2-type compounds show Curie−Weiss behavior above 40.0(2) K and 45.5(2) K with magnetic moments of 7.98(1)μB for Eu(Zn0.48(2)Ge0.52(2))2 and 7.96(1) μB for Eu(Zn0.30(2)Ge0.70(2))2, respectively, indicating a (4f)7 electronic configuration for Eu atoms (Eu2+). The Zintl-Klemm formalism accounts for the lower limit of Ge content in the AlB2-type phases, but does not identify the observed upper limit. In a companion paper, the intrinsic relationship among chemical structures, compositions, and electronic structures are analyzed by theoretical electronic structure calculations of several models of these phases and discussed to provide comprehensive interpretation of these structural results.