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Free keywords:
binary gallide, chemical bonding, crystal structure, Eu electronic configuration, phase diagram, QTAIM, single crystal X-ray diffraction, TEM
Abstract:
The 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. © 2023 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbH.
