Structural complexity in the apparently simple crystal structure of Be2Ru.

Abstract

The structural features of the hexagonal layered crystal structure of Be2Ru (a = 5.7508(3) Å, c = 3.0044(2) Å, space group P -62m) were investigated by single crystal X-ray diffraction and transmission electron microscopy (TEM). The residual electron density and high-resolution TEM images show that the real structure can be described as an intergrowth of the main hexagonal matrix of the Fe2P type with minor orthorhombic inclusions of its stacking variants. Such atomic arrangement is stabilized by the charge transfer from Be to Ru and by a system of polar three- and four-atomic bonds involving both components. The calculated electronic density of states (DOS) of Be2Ru revealed, contrarily to typical intermetallic compounds, a pseudo gap (dip) in the vicinity of the Fermi level. The temperature dependence of the electrical resistivity of Be2Ru shows metal behavior in agreement with the non-zero DOS at the Fermi level.