Affiliation:
1. Department Chemische Metallkunde Max-Planck-Institut für Chemische Physik fester Stoffe Nöthnitzer Str. 40 01187 Dresden Germany
Abstract
AbstractThe europium gallide Eu1‐xGa2+3x (x is between 0.06 and 0.07) has been synthesized and its crystal structure has been refined from single crystal X‐ray diffraction data. Eu1‐xGa2+3x crystallizes with hexagonal structure related to the AlB2‐type (space group P6/mmm, a=4.354 Å, c=4.485 Å). The structure refinement finished with R(F)=0.015 for 1603 reflections revealing a defect occupation of the Eu position (93 %) and additional Ga position, yielding the non‐integer element ratio. From magnetic susceptibility measurements, EuGa2 and Eu1‐xGa2+3x phases show the 4f 7 (Eu+2) oxidation state. The analysis of effective atomic charges within the Quantum Theory of Atoms in Molecules reveals the formation of four‐bonded Ga species with low electron demand (in comparison to the three‐bonded in AlB2‐type and four‐bonded in the KHg2‐type structures) and shows, that Eu1‐xGa2+3x represents a new way of stabilizing intermetallic structures formed at valence electron concentration, which does not allow to apply Zintl‐like electron counting.
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