Defects in a disordered world: The structure of glassy GeSe²

The full set of partial structure factors for the prototypical network glass GeSe² was measured using the method of isotopic substitution in neutron diffraction. The basic building block of the network is the Ge(Se_1/2)₄ tetrahedron in which 34(5)% of the Ge reside in edge-sharing configurations. The intrinsic chemical order of the glass is, however, broken with a maximum of 25(5)% Ge and 20(5)% Se being involved in homopolar bonds at distances of 2.42(2) and 2.32(2) Å, respectively.