Structural Characterization of the Intermetallic Phase EuZn_xIn_(4-x) (x ≈ 1.1-1.2). Zn and In Site-Preferences in the BaAl4 Structure-Type from Computational Analysis

摘要

The ternary phase EuZn_xIn_(4-x) has been identified as the main product of reactions of Eu, Zn, and In by using the In-flux method and characterized by both powder and single-crystal X-ray diffraction. The structure belongs to the common BaAU-type (tetragonal space group I4/mm, Pearson code ti10) with lattice parameters of a = 4.5610(9) A, c = 12.049(3) A for composition EuZn_(1.10(12))In_(2.90) and a = 4.5463(3) A, c = 12.028(2) A for composition EuZn_(1.18(2))In_(2.82), respectively. In this structure, the Eu atoms are situated at the center of 18-vertex Fedorov polyhedra made of Zn and In atoms, where the 4d site is preferentially occupied by In and the 4e site is occupied by randomly mixed Zn and In atoms. Theoretical investigations using tight-binding linear muffin-tin orbital (TB-LMTO) method provide rationale for the observed site preferences and suggest potentially wider homogeneity range than the experimentally established for EuZn_xIn_(4-x) (x ≈ 1.1).